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Barrie U, Floyd K, Datta A, Wetzel DM. MAPK/ERK Activation in Macrophages Promotes Leishmania Internalization and Pathogenesis. Microbes Infect 2024:105353. [PMID: 38763478 DOI: 10.1016/j.micinf.2024.105353] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 05/06/2024] [Accepted: 05/07/2024] [Indexed: 05/21/2024]
Abstract
The obligate intracellular parasite Leishmania binds several receptors to trigger uptake by phagocytic cells, ultimately resulting in visceral or cutaneous leishmaniasis. A series of signaling pathways in host cells, which are critical for establishment and persistence of infection, are activated during Leishmania internalization. Thus, preventing Leishmania uptake by phagocytes could be a novel therapeutic strategy for leishmaniasis. However, the host cellular machinery mediating promastigote and amastigote uptake is not well understood. Here, using small molecule inhibitors of Mitogen-activated protein/Extracellular signal regulated kinases (MAPK/ERK), we demonstrate that ERK1/2 mediates Leishmania amazonensis uptake and (to a lesser extent) phagocytosis of beads by macrophages. We find that inhibiting host MEK1/2 or ERK1/2 leads to inefficient amastigote uptake. Moreover, using inhibitors and primary macrophages lacking spleen tyrosine kinase (SYK) or Abl family kinases, we show that SYK and Abl family kinases mediate Raf, MEK, and ERK1/2 activity and are necessary for uptake. Finally, we demonstrate that trametinib, a MEK1/2 inhibitor used to treat cancer, reduces disease severity and parasite burden in Leishmania-infected mice, even if it is started after lesions develop. Our results show that maximal Leishmania infection requires MAPK/ERK and highlight potential for MAPK/ERK-mediated signaling pathways to be novel therapeutic targets for leishmaniasis.
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Affiliation(s)
- Umaru Barrie
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas, 75390, United States; Medical Scientist Training Program, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas, 75390, United States
| | - Katherine Floyd
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas, 75390, United States
| | - Arani Datta
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas, 75390, United States
| | - Dawn M Wetzel
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas, 75390, United States; Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas, 75390, United States.
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2
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Wei L, Barrie U, Aloisio GM, Khuong FTH, Arang N, Datta A, Kaushansky A, Wetzel DM. Using machine learning to dissect host kinases required for Leishmania internalization and development. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.16.593986. [PMID: 38798624 PMCID: PMC11118464 DOI: 10.1101/2024.05.16.593986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
The Leishmania life cycle alternates between promastigotes, found in the sandfly, and amastigotes, found in mammals. When an infected sandfly bites a host, promastigotes are engulfed by phagocytes ( i.e. , neutrophils, dendritic cells, and macrophages) to establish infection. When these phagocytes die or break down, amastigotes must be re-internalized to survive within the acidic phagolysosome and establish disease. To define host kinase regulators of Leishmania promastigote and amastigote uptake and survival within macrophages, we performed an image-based kinase regression screen using a panel of 38 kinase inhibitors with unique and overlapping kinase targets. We also targeted inert beads to complement receptor 3 (CR3) or Fcγ receptors (FcR) as controls by coating them with complement/C3bi or IgG respectively. Through this approach, we identified several host kinases that regulate receptor-mediated phagocytosis and/or the uptake of L. amazonensis . Findings included kinases previously implicated in Leishmania uptake (such as SRC family kinases (SFK), Abl family kinases (ABL1/c-Abl, ABL2/Arg), and spleen tyrosine kinase (SYK)); we also uncovered many novel kinases. These methods also predicted kinases necessary for promastigotes to convert to amastigotes or for amastigotes to survive within macrophages. Overall, our results suggest that the concerted action of multiple interconnected networks of host kinases are needed over the course of Leishmania infection, and that the kinases required for the parasite's life cycle substantially differ depending on which receptors are bound and the life cycle stage that is internalized. In addition, using our screen, we identified kinases that preferentially regulate the uptake of parasites over beads, indicating that the methods required for Leishmania to be internalized by macrophages differ significantly from generalized phagocytic mechanisms. Our findings are intended to be used as a hypothesis generation resource for the broader scientific community studying the roles of kinases in host-pathogen interactions.
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Tengganu IF, Arias Padilla LF, Munera Lopez J, Liu J, Brown PT, Murray JM, Hu K. The cortical microtubules of Toxoplasma gondii underlie the helicity of parasite movement. J Cell Sci 2023; 136:jcs261270. [PMID: 37675776 PMCID: PMC10499027 DOI: 10.1242/jcs.261270] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 08/04/2023] [Indexed: 09/08/2023] Open
Abstract
Motility is essential for apicomplexan parasites to infect their hosts. In a three-dimensional (3D) environment, the apicomplexan parasite Toxoplasma gondii moves along a helical path. The cortical microtubules, which are ultra-stable and spirally arranged, have been considered to be a structure that guides the long-distance movement of the parasite. Here, we address the role of the cortical microtubules in parasite motility, invasion and egress by utilizing a previously generated mutant (dubbed 'TKO') in which these microtubules are destabilized in mature parasites. We found that the cortical microtubules in ∼80% of the non-dividing (i.e. daughter-free) TKO parasites are much shorter than normal. The extent of depolymerization was further exacerbated upon commencement of daughter formation or cold treatment, but parasite replication was not affected. In a 3D Matrigel matrix, the TKO mutant moved directionally over long distances, but along trajectories that were significantly more linear (i.e. less helical) than those of wild-type parasites. Interestingly, this change in trajectory did not impact either movement speed in the matrix or the speed and behavior of the parasite during entry into and egress from the host cell.
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Affiliation(s)
- Isadonna F. Tengganu
- Biodesign Center for Mechanisms of Evolution/School of Life Sciences, Arizona State University, Tempe, AZ 85284, USA
| | - Luisa F. Arias Padilla
- Biodesign Center for Mechanisms of Evolution/School of Life Sciences, Arizona State University, Tempe, AZ 85284, USA
| | - Jonathan Munera Lopez
- Biodesign Center for Mechanisms of Evolution/School of Life Sciences, Arizona State University, Tempe, AZ 85284, USA
| | - Jun Liu
- Department of Biology, Indiana University, Bloomington, ID 47405, USA
| | - Peter T. Brown
- Department of Physics and Center for Biological Physics, Arizona State University, Tempe, AZ 85284, USA
| | - John M. Murray
- Biodesign Center for Mechanisms of Evolution/School of Life Sciences, Arizona State University, Tempe, AZ 85284, USA
| | - Ke Hu
- Biodesign Center for Mechanisms of Evolution/School of Life Sciences, Arizona State University, Tempe, AZ 85284, USA
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4
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Martinez M, Mageswaran SK, Guérin A, Chen WD, Thompson CP, Chavin S, Soldati-Favre D, Striepen B, Chang YW. Origin and arrangement of actin filaments for gliding motility in apicomplexan parasites revealed by cryo-electron tomography. Nat Commun 2023; 14:4800. [PMID: 37558667 PMCID: PMC10412601 DOI: 10.1038/s41467-023-40520-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 07/26/2023] [Indexed: 08/11/2023] Open
Abstract
The phylum Apicomplexa comprises important eukaryotic parasites that invade host tissues and cells using a unique mechanism of gliding motility. Gliding is powered by actomyosin motors that translocate host-attached surface adhesins along the parasite cell body. Actin filaments (F-actin) generated by Formin1 play a central role in this critical parasitic activity. However, their subcellular origin, path and ultrastructural arrangement are poorly understood. Here we used cryo-electron tomography to image motile Cryptosporidium parvum sporozoites and reveal the cellular architecture of F-actin at nanometer-scale resolution. We demonstrate that F-actin nucleates at the apically positioned preconoidal rings and is channeled into the pellicular space between the parasite plasma membrane and the inner membrane complex in a conoid extrusion-dependent manner. Within the pellicular space, filaments on the inner membrane complex surface appear to guide the apico-basal flux of F-actin. F-actin concordantly accumulates at the basal end of the parasite. Finally, analyzing a Formin1-depleted Toxoplasma gondii mutant pinpoints the upper preconoidal ring as the conserved nucleation hub for F-actin in Cryptosporidium and Toxoplasma. Together, we provide an ultrastructural model for the life cycle of F-actin for apicomplexan gliding motility.
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Affiliation(s)
- Matthew Martinez
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Shrawan Kumar Mageswaran
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Amandine Guérin
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - William David Chen
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Cameron Parker Thompson
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sabine Chavin
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Boris Striepen
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi-Wei Chang
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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Gui L, O'Shaughnessy WJ, Cai K, Reetz E, Reese ML, Nicastro D. Cryo-tomography reveals rigid-body motion and organization of apicomplexan invasion machinery. Nat Commun 2023; 14:1775. [PMID: 36997532 PMCID: PMC10063558 DOI: 10.1038/s41467-023-37327-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 03/10/2023] [Indexed: 04/03/2023] Open
Abstract
The apical complex is a specialized collection of cytoskeletal and secretory machinery in apicomplexan parasites, which include the pathogens that cause malaria and toxoplasmosis. Its structure and mechanism of motion are poorly understood. We used cryo-FIB-milling and cryo-electron tomography to visualize the 3D-structure of the apical complex in its protruded and retracted states. Averages of conoid-fibers revealed their polarity and unusual nine-protofilament arrangement with associated proteins connecting and likely stabilizing the fibers. Neither the structure of the conoid-fibers nor the architecture of the spiral-shaped conoid complex change during protrusion or retraction. Thus, the conoid moves as a rigid body, and is not spring-like and compressible, as previously suggested. Instead, the apical-polar-rings (APR), previously considered rigid, dilate during conoid protrusion. We identified actin-like filaments connecting the conoid and APR during protrusion, suggesting a role during conoid movements. Furthermore, our data capture the parasites in the act of secretion during conoid protrusion.
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Affiliation(s)
- Long Gui
- Department of Cell Biology, University of Texas, Southwestern Medical Center, Dallas, TX, USA
| | - William J O'Shaughnessy
- Department of Pharmacology, University of Texas, Southwestern Medical Center, Dallas, TX, USA
| | - Kai Cai
- Department of Cell Biology, University of Texas, Southwestern Medical Center, Dallas, TX, USA
- Department of Biophysics, University of Texas, Southwestern Medical Center, Dallas, TX, USA
| | - Evan Reetz
- Department of Cell Biology, University of Texas, Southwestern Medical Center, Dallas, TX, USA
| | - Michael L Reese
- Department of Pharmacology, University of Texas, Southwestern Medical Center, Dallas, TX, USA.
- Department of Biochemistry, University of Texas, Southwestern Medical Center, Dallas, TX, USA.
| | - Daniela Nicastro
- Department of Cell Biology, University of Texas, Southwestern Medical Center, Dallas, TX, USA.
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6
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Nemati S, Pazoki H, Mohammad Rahimi H, Asadzadeh Aghdaei H, Shahrokh S, Baghaei K, Mirjalali H, Zali MR. Toxoplasma gondii profilin and tachyzoites RH strain may manipulate autophagy via downregulating Atg5 and Atg12 and upregulating Atg7. Mol Biol Rep 2021; 48:7041-7047. [PMID: 34453672 DOI: 10.1007/s11033-021-06667-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 08/18/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Autophagy process is an important defense mechanism against intracellular infection. This process plays a critical role in limiting the development of Toxoplasma gondii. This study aimed to investigate the effects of T. gondii profilin and tachyzoites on the expression of autophagy genes. METHODS AND RESULTS PMA-activated THP-1 cell line was incubated with T. gondii profilin and tachyzoites for 6 h. After RNA extraction and cDNA synthesis, the expression of Atg5, Atg7, Atg12, and LC3b was evaluated using real-time PCR. The results revealed statistically significant downregulation of Atg5 for 1.43 (P-value = 0.0062) and 4.15 (P-value = 0.0178) folds after treatment with T. gondii profilin and tachyzoites, respectively. Similar to Atg 5, Atg 12 revealed a statistically significant downregulation for profilin (1.41 fold; P-value = 0.0047) and T. gondii tachyzoites (3.25 fold; P-value = 0.011). The expression of Atg7 elevated in both T. gondii profilin (2.083 fold; P-value = 0.0087) and tachyzoites (1.64 fold; P-value = 0.206). T. gondii profilin and tachyzoites downregulated (1.04 fold; P-value = 0.0028) and upregulated (twofold; P-value = 0.091) the expression of LC3b, respectively. CONCLUSIONS Our findings suggest that T. gondii and profilin may manipulate autophagy via preventing from the formation of Atg5-12-16L complex to facilitate replication of T. gondii and development of toxoplasmosis.
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Affiliation(s)
- Sara Nemati
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hossein Pazoki
- Basic and Molecular Epidemiology of Gastrointestinal Disorders Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hanieh Mohammad Rahimi
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hamid Asadzadeh Aghdaei
- Basic and Molecular Epidemiology of Gastrointestinal Disorders Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Shabnam Shahrokh
- Gastroenterology and Liver Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Kaveh Baghaei
- Basic and Molecular Epidemiology of Gastrointestinal Disorders Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Hamed Mirjalali
- Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
| | - Mohammad Reza Zali
- Gastroenterology and Liver Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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McGovern OL, Rivera-Cuevas Y, Carruthers VB. Emerging Mechanisms of Endocytosis in Toxoplasma gondii. Life (Basel) 2021; 11:life11020084. [PMID: 33503859 PMCID: PMC7911406 DOI: 10.3390/life11020084] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 01/19/2021] [Accepted: 01/20/2021] [Indexed: 02/07/2023] Open
Abstract
Eukaryotes critically rely on endocytosis of autologous and heterologous material to maintain homeostasis and to proliferate. Although mechanisms of endocytosis have been extensively identified in mammalian and plant systems along with model systems including budding yeast, relatively little is known about endocytosis in protozoan parasites including those belonging to the phylum Apicomplexa. Whereas it has been long established that the apicomplexan agents of malaria (Plasmodium spp.) internalize and degrade hemoglobin from infected red blood cells to acquire amino acids for growth, that the related and pervasive parasite Toxoplasma gondii has a functional and active endocytic system was only recently discovered. Here we discuss emerging and hypothesized mechanisms of endocytosis in Toxoplasma gondii with reference to model systems and malaria parasites. Establishing a framework for potential mechanisms of endocytosis in Toxoplasma gondii will help guide future research aimed at defining the molecular basis and biological relevance of endocytosis in this tractable and versatile parasite.
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Lakho SA, Haseeb M, Huang J, Yang Z, Hasan MW, Aleem MT, Memon MA, Song X, Yan R, Xu L, Li X. Actin-depolymerizing factor from Eimeria tenella promotes immunogenic function of chicken dendritic cells. Parasitol Res 2021; 120:579-592. [PMID: 33438042 DOI: 10.1007/s00436-020-07016-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 12/08/2020] [Indexed: 02/02/2023]
Abstract
Dendritic cells play a crucial role in inducing antigen-specific immunity to pathogens. During host-parasite interaction, host immune response to the parasite molecules is considered essential for recognizing novel antigens for control strategies. Therefore, in the present study, chicken dendritic cells (DCs) (ChDCs), derived from spleens were used to evaluate their capacity to proliferate and differentiate autologous T lymphocytes in response to actin-depolymerizing factor from Eimeria tenella (EtADF). Immunoblot analysis showed that recombinant EtADF protein (rEtADF) was able to interact with rat anti-rEtADF antibodies. The immunofluorescence test confirmed rEtADF binding on ChDCs surface. Flow cytometric analysis revealed that phenotypes for MHCII, CD1.1, CD11c, CD80, and CD86 were increased in ChDCs after rEtADF treatment. qRT-PCR results indicated that ChDCs triggered TLR signaling in response to rEtADF, and suppressed Wnt signaling. Transcript levels of CD83, CCL5, and CCR7 in ChDCs were improved following rEtADF treatment. In addition, rEtADF promoted DC-directed T cell proliferation and differentiation of naïve T cells into CD3+/CD4+ T cells in DC/T cell co-incubation system. Cytokine analysis of rEtADF-pulsed ChDCs showed increased levels of IL-12 and IFN-γ, while IL-10 and TGF-β remained unchanged. Moreover, rEtADF-treated ChDCs enhanced production of IFN-γ when incubated with T cells, and IL-4 secretion remained unchanged. Our findings indicted that rEtADF could facilitate the polarization of Th1 immune cells by triggering both host DCs and T cells. Our findings provide useful insights into future work aimed at anticoccidial vaccine strategies.
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Affiliation(s)
- Shakeel Ahmed Lakho
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - Muhammad Haseeb
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - Jianmei Huang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - Zhang Yang
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - Muhammad Waqqas Hasan
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - Muhammad Tahir Aleem
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - Muhammad Ali Memon
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - XiaoKai Song
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - RuoFeng Yan
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - Lixin Xu
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China
| | - XiangRui Li
- MOE Joint International Research Laboratory of Animal Health and Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, Jiangsu, People's Republic of China.
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Guleria V, Pal T, Sharma B, Chauhan S, Jaiswal V. Pharmacokinetic and molecular docking studies to design antimalarial compounds targeting Actin I. Int J Health Sci (Qassim) 2021; 15:4-15. [PMID: 34916893 PMCID: PMC8589829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/30/2022] Open
Abstract
OBJECTIVE Malaria is an ancient disease that still causes more than 200 million of cases 7 with high mortality globally. Identification of new drug targets and development of novel antimalarial drugs with unique mode of action encounter the drug resistance and reduce the mortality by Plasmodium parasites. Actin protein is one of the key proteins in Plasmodium falciparum playing multifarious important roles including transport, cell motility, cell division, and shape determination. This study investigated Actin I as a drug target, in silico screening of diverse molecules through molecular docking was considered. Further, pharmacokinetic parameters of the selected molecules from the docking and interaction studies were planned to propose the lead molecules.b. METHODS Molecules were selected according to score and protein ligand interaction and selected molecules were subjected for pharmacokinetic studies to investigate important drug parameters. RESULTS The docked molecules were ranked according to the binding score and good interaction pattern was observed with Actin I within top 20 scoring molecules. The selected molecules also had optimum pharmacokinetic parameters. CONCLUSION The current study provides a set of hit molecules which can be further explored through in vitro and in vivo experiments for the development of potential drugs against malaria, there by encountering drug resistance and establishing Actin I as an important drug target.
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Affiliation(s)
- Vandana Guleria
- Department of Biotechnology, Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Solan, Himachal Pradesh, India
| | - Tarun Pal
- Department of Biotechnology, Vignan’s Foundation for Science, Technology and Research, Vadlamudi, Guntur, Andhra Pradesh, India
| | - Bhanu Sharma
- Department of Biotechnology, Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Solan, Himachal Pradesh, India
| | - Shweta Chauhan
- Department of Biotechnology, Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Solan, Himachal Pradesh, India
| | - Varun Jaiswal
- Department of Engineering, School of Electrical and Computer Science Engineering, Shoolini University of Biotechnology and Management Sciences, Solan, Himachal Pradesh, India,Department of Food and Nutrition, College of BioNano Technology, Gachon University, Seongnam-si 13120, Gyeonggi-do, Korea,Address for correspondence: Dr. Varun Jaiswal, Department of Food and Nutrition, College of BioNano Technology, Gachon University, Seongnam-si 13120, Gyeonggi-do, Korea. E-mail:
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Ullah I, Gahalawat S, Booshehri LM, Niederstrasser H, Majumdar S, Leija C, Bradford JM, Hu B, Ready JM, Wetzel DM. An Antiparasitic Compound from the Medicines for Malaria Venture Pathogen Box Promotes Leishmania Tubulin Polymerization. ACS Infect Dis 2020; 6:2057-2072. [PMID: 32686409 DOI: 10.1021/acsinfecdis.0c00122] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The few frontline antileishmanial drugs are poorly effective and toxic. To search for new drugs for this neglected tropical disease, we tested the activity of compounds in the Medicines for Malaria Venture (MMV) "Pathogen Box" against Leishmania amazonensis axenic amastigotes. Screening yielded six discovery antileishmanial compounds with EC50 values from 50 to 480 nM. Concentration-response assays demonstrated that the best hit, MMV676477, had mid-nanomolar cytocidal potency against intracellular Leishmania amastigotes, Trypanosoma brucei, and Plasmodium falciparum, suggesting broad antiparasitic activity. We explored structure-activity relationships (SAR) within a small group of MMV676477 analogs and observed a wide potency range (20-5000 nM) against axenic Leishmania amastigotes. Compared to MMV676477, our most potent analog, SW41, had ∼5-fold improved antileishmanial potency. Multiple lines of evidence suggest that MMV676477 selectively disrupts Leishmania tubulin dynamics. Morphological studies indicated that MMV676477 and analogs affected L. amazonensis during cell division. Differential centrifugation showed that MMV676477 promoted partitioning of cellular tubulin toward the polymeric form in parasites. Turbidity assays with purified Leishmania and porcine tubulin demonstrated that MMV676477 promoted leishmanial tubulin polymerization in a concentration-dependent manner. Analogs' antiparasitic activity correlated with their ability to facilitate purified Leishmania tubulin polymerization. Chemical cross-linking demonstrated binding of the MMV676477 scaffold to purified Leishmania tubulin, and competition studies established a correlation between binding and antileishmanial activity. Our studies demonstrate that MMV676477 is a potent antiparasitic compound that preferentially promotes Leishmania microtubule polymerization. Due to its selectivity for and broad-spectrum activity against multiple parasites, this scaffold shows promise for antiparasitic drug development.
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Affiliation(s)
- Imran Ullah
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
| | - Suraksha Gahalawat
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
| | - Laela M. Booshehri
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
| | - Hanspeter Niederstrasser
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
| | - Shreoshi Majumdar
- Department of Biophysics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
| | - Christopher Leija
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
| | - James M. Bradford
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
| | - Bin Hu
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
| | - Joseph M. Ready
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
| | - Dawn M. Wetzel
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
- Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, Texas 75390, United States
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Gutiérrez-Sánchez M, Carrasco-Yepez MM, Herrera-Díaz J, Rojas-Hernández S. Identification of differential protein recognition pattern between Naegleria fowleri and Naegleria lovaniensis. Parasite Immunol 2020; 42:e12715. [PMID: 32191816 DOI: 10.1111/pim.12715] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 03/05/2020] [Accepted: 03/13/2020] [Indexed: 12/15/2022]
Abstract
Many pathogenicity factors are involved in the development of primary amoebic meningoencephalitis (PAM) caused by N fowleri. However, most of them are not exclusive for N fowleri and they have not even been described in other nonpathogenic Naegleria species. Therefore, the objective of this work was to identify differential proteins and protein pattern recognition between Naegleria fowleri and Naegleria lovaniensis using antibodies anti-N fowleri as strategy to find vaccine candidates against meningoencephalitis. Electrophoresis and Western blots conventional and 2-DE were performed for the identification of antigenic proteins, and these were analysed by the mass spectrometry technique. The results obtained in 2-DE gels and Western blot showed very notable differences in spot intensity between these two species, specifically those with relative molecular weight of 100, 75, 50 and 19 kDa. Some spots corresponding to these molecular weights were identified as actin fragment, myosin II, heat shock protein, membrane protein Mp2CL5 among others, with differences in theoretical post-translational modifications. In this work, we found differences in antigenic proteins between both species, proteins that could be used for a further development of vaccines against N fowleri infection.
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Affiliation(s)
- Mara Gutiérrez-Sánchez
- Laboratorio de Inmunobiología Molecular y Celular, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México City, Mexico
| | - Maria Maricela Carrasco-Yepez
- Laboratorio de Microbiología, Grupo CyMA, Unidad de Investigación Interdisciplinaria en Ciencias de la Salud y la Educación, Universidad Nacional Autónoma de México, UNAM FES Iztacala, Tlalnepantla, Mexico
| | - Jorge Herrera-Díaz
- Unidad de Servicios de Apoyo a la Investigación y la Industria, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | - Saul Rojas-Hernández
- Laboratorio de Inmunobiología Molecular y Celular, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, México City, Mexico
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12
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Merino F, Pospich S, Raunser S. Towards a structural understanding of the remodeling of the actin cytoskeleton. Semin Cell Dev Biol 2019; 102:51-64. [PMID: 31836290 PMCID: PMC7221352 DOI: 10.1016/j.semcdb.2019.11.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 11/27/2019] [Accepted: 11/28/2019] [Indexed: 12/03/2022]
Abstract
Actin filaments (F-actin) are a key component of eukaryotic cells. Whether serving as a scaffold for myosin or using their polymerization to push onto cellular components, their function is always related to force generation. To control and fine-tune force production, cells have a large array of actin-binding proteins (ABPs) dedicated to control every aspect of actin polymerization, filament localization, and their overall mechanical properties. Although great advances have been made in our biochemical understanding of the remodeling of the actin cytoskeleton, the structural basis of this process is still being deciphered. In this review, we summarize our current understanding of this process. We outline how ABPs control the nucleation and disassembly, and how these processes are affected by the nucleotide state of the filaments. In addition, we highlight recent advances in the understanding of actomyosin force generation, and describe recent advances brought forward by the developments of electron cryomicroscopy.
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Affiliation(s)
- Felipe Merino
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Sabrina Pospich
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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13
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Craig EW, Mueller DM, Bigge BM, Schaffer M, Engel BD, Avasthi P. The elusive actin cytoskeleton of a green alga expressing both conventional and divergent actins. Mol Biol Cell 2019; 30:2827-2837. [PMID: 31532705 PMCID: PMC6789165 DOI: 10.1091/mbc.e19-03-0141] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 09/06/2019] [Accepted: 09/10/2019] [Indexed: 12/13/2022] Open
Abstract
The green alga Chlamydomonas reinhardtii is a leading model system to study photosynthesis, cilia, and the generation of biological products. The cytoskeleton plays important roles in all of these cellular processes, but to date, the filamentous actin network within Chlamydomonas has remained elusive. By optimizing labeling conditions, we can now visualize distinct linear actin filaments at the posterior of the nucleus in both live and fixed vegetative cells. Using in situ cryo-electron tomography, we confirmed this localization by directly imaging actin filaments within the native cellular environment. The fluorescently labeled structures are sensitive to the depolymerizing agent latrunculin B (Lat B), demonstrating the specificity of our optimized labeling method. Interestingly, Lat B treatment resulted in the formation of a transient ring-like filamentous actin structure around the nucleus. The assembly of this perinuclear ring is dependent upon a second actin isoform, NAP1, which is strongly up-regulated upon Lat B treatment and is insensitive to Lat B-induced depolymerization. Our study combines orthogonal strategies to provide the first detailed visual characterization of filamentous actins in Chlamydomonas, allowing insights into the coordinated functions of two actin isoforms expressed within the same cell.
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Affiliation(s)
- Evan W. Craig
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160
| | - David M. Mueller
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160
| | - Brae M. Bigge
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160
| | - Miroslava Schaffer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Benjamin D. Engel
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Prachee Avasthi
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160
- Department of Ophthalmology, University of Kansas Medical Center, Kansas City, KS 66160
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14
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Unusual dynamics of the divergent malaria parasite PfAct1 actin filament. Proc Natl Acad Sci U S A 2019; 116:20418-20427. [PMID: 31548388 DOI: 10.1073/pnas.1906600116] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Gliding motility and host cell invasion by the apicomplexan parasite Plasmodium falciparum (Pf), the causative agent of malaria, is powered by a macromolecular complex called the glideosome that lies between the parasite plasma membrane and the inner membrane complex. The glideosome core consists of a single-headed class XIV myosin PfMyoA and a divergent actin PfAct1. Here we use total internal reflection fluorescence microscopy to visualize growth of individual unstabilized PfAct1 filaments as a function of time, an approach not previously used with this actin isoform. Although PfAct1 was thought to be incapable of forming long filaments, filaments grew as long as 30 µm. Polymerization occurs via a nucleation-elongation mechanism, but with an ∼4 µM critical concentration, an order-of-magnitude higher than for skeletal actin. Protomers disassembled from both the barbed and pointed ends of the actin filament with similar fast kinetics of 10 to 15 subunits/s. Rapid treadmilling, where the barbed end of the filament grows and the pointed end shrinks while maintaining an approximately constant filament length, was visualized near the critical concentration. Once ATP has been hydrolyzed to ADP, the filament becomes very unstable, resulting in total dissolution in <40 min. Dynamics at the filament ends are suppressed in the presence of inorganic phosphate or more efficiently by BeFX A chimeric PfAct1 with a mammalian actin D-loop forms a more stable filament. These unusual dynamic properties distinguish PfAct1 from more canonical actins, and likely contribute to the difficultly in visualizing PfAct1 filaments in the parasite.
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15
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Motility and cytoskeletal organisation in the archigregarine Selenidium pygospionis (Apicomplexa): observations on native and experimentally affected parasites. Parasitol Res 2019; 118:2651-2667. [PMID: 31270680 DOI: 10.1007/s00436-019-06381-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 06/19/2019] [Indexed: 10/26/2022]
Abstract
Representatives of Apicomplexa perform various kinds of movements that are linked to the different stages of their life cycle. Ancestral apicomplexan lineages, including gregarines, represent organisms suitable for research into the evolution and diversification of motility within the group. The vermiform trophozoites and gamonts of the archigregarine Selenidium pygospionis perform a very active type of bending motility. Experimental assays and subsequent light, electron, and confocal microscopic analyses demonstrated the fundamental role of the cytoskeletal proteins actin and tubulin in S. pygospionis motility and allowed us to compare the mechanism of its movement to the gliding machinery (the so-called glideosome concept) described in apicomplexan zoites. Actin-modifying drugs caused a reduction in the movement speed (cytochalasin D) or stopped the motility of archigregarines completely (jasplakinolide). Microtubule-disrupting drugs (oryzalin and colchicine) had an even more noticeable effect on archigregarine motility. The fading and disappearance of microtubules were documented in ultrathin sections, along with the formation of α-tubulin clusters visible after the immunofluorescent labelling of drug-treated archigregarines. The obtained data indicate that subpellicular microtubules most likely constitute the main motor structure involved in S. pygospionis bending motility, while actin has rather a supportive function.
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16
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Tosetti N, Dos Santos Pacheco N, Soldati-Favre D, Jacot D. Three F-actin assembly centers regulate organelle inheritance, cell-cell communication and motility in Toxoplasma gondii. eLife 2019; 8:e42669. [PMID: 30753127 PMCID: PMC6372287 DOI: 10.7554/elife.42669] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 01/29/2019] [Indexed: 01/06/2023] Open
Abstract
Toxoplasma gondii possesses a limited set of actin-regulatory proteins and relies on only three formins (FRMs) to nucleate and polymerize actin. We combined filamentous actin (F-actin) chromobodies with gene disruption to assign specific populations of actin filaments to individual formins. FRM2 localizes to the apical juxtanuclear region and participates in apicoplast inheritance. Restricted to the residual body, FRM3 maintains the intravacuolar cell-cell communication. Conoidal FRM1 initiates a flux of F-actin crucial for motility, invasion and egress. This flux depends on myosins A and H and is controlled by phosphorylation via PKG (protein kinase G) and CDPK1 (calcium-dependent protein kinase 1) and by methylation via AKMT (apical lysine methyltransferase). This flux is independent of microneme secretion and persists in the absence of the glideosome-associated connector (GAC). This study offers a coherent model of the key players controlling actin polymerization, stressing the importance of well-timed post-translational modifications to power parasite motility.
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Affiliation(s)
- Nicolò Tosetti
- Department of Microbiology and Molecular Medicine, CMUUniversity of GenevaGenevaSwitzerland
| | | | | | - Damien Jacot
- Department of Microbiology and Molecular Medicine, CMUUniversity of GenevaGenevaSwitzerland
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17
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Kumar V, Behl A, Kapoor P, Nayak B, Singh G, Singh AP, Mishra S, Kang TS, Mishra PC, Hora R. Inner membrane complex 1l protein of Plasmodium falciparum links membrane lipids with cytoskeletal element 'actin' and its associated motor 'myosin'. Int J Biol Macromol 2018; 126:673-684. [PMID: 30599160 DOI: 10.1016/j.ijbiomac.2018.12.239] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 12/25/2018] [Accepted: 12/26/2018] [Indexed: 01/14/2023]
Abstract
The inner membrane complex (IMC) is a defining feature of apicomplexans comprising of lipid and protein components involved in gliding motility and host cell invasion. Motility of Plasmodium parasites is accomplished by an actin and myosin based glideosome machinery situated between the parasite plasma membrane (PPM) and IMC. Here, we have studied in vivo expression and localization of a Plasmodium falciparum (Pf) IMC protein 'PfIMC1l' and characterized it functionally by using biochemical assays. We have identified cytoskeletal protein 'actin' and motor protein 'myosin' as novel binding partners of PfIMC1l, alongside its interaction with the lipids 'cholesterol' and 'phosphatidyl-inositol 4, 5 bisphosphate' (PIP2). While actin and myosin compete for interaction with PfIMC1l, actin and either of the lipids (cholesterol or PIP2) simultaneously bind PfIMC1l. Interestingly, PfIMC1l showed enhanced binding with actin in the presence of calcium ions, and displayed direct binding with calcium. Based on our in silico analysis and experimental data showing PfIMC1l-actin/myosin and PfIMC1l-lipid interactions, we propose that this protein may anchor the IMC membrane with the parasite gliding apparatus. Considering its binding with key proteins involved in motility viz. myosin and actin (with calcium dependence), we suggest that PfIMC1l may have a role in the locomotion of Plasmodium.
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Affiliation(s)
- Vikash Kumar
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Ankita Behl
- Department of Biotechnology, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Payal Kapoor
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Bandita Nayak
- CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Gurbir Singh
- Department of Chemistry, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Amrit Pal Singh
- Department of Pharmaceutical Science, Guru Nanak Dev University, Amritsar, Punjab, India
| | - Satish Mishra
- CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, India
| | - Tejwant Singh Kang
- Department of Chemistry, Guru Nanak Dev University, Amritsar, Punjab, India
| | | | - Rachna Hora
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, India.
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18
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Baroni L, Pereira LM, Maciver SK, Yatsuda AP. Functional characterisation of the actin-depolymerising factor from the apicomplexan Neospora caninum (NcADF). Mol Biochem Parasitol 2018; 224:26-36. [PMID: 30040977 DOI: 10.1016/j.molbiopara.2018.07.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 07/15/2018] [Accepted: 07/15/2018] [Indexed: 01/20/2023]
Abstract
Neospora caninum is an apicomplexan parasite that causes infectious abortion in cows. As an obligate intracellular parasite, N. caninum requires a host cell environment to survive and replicate. The locomotion and invasion mechanisms of apicomplexan parasites are centred on the actin-myosin system to propel the parasite forwards and into the host cell. The functions of actin, an intrinsically dynamic protein, are modulated by actin-binding proteins (ABPs). Actin-depolymerising factor (ADF) is a ubiquitous ABP responsible for accelerating actin turnover in eukaryotic cells and is one of the few known conserved ABPs from apicomplexan parasites. Apicomplexan ADFs have nonconventional properties compared with ADF/cofilins from higher eukaryotes. In the present paper, we characterised the ADF from N. caninum (NcADF) using computational and in vitro biochemical approaches to investigate its function in rabbit muscle actin dynamics. Our predicted computational tertiary structure of NcADF demonstrated a conserved structure and phylogeny with respect to other ADF/cofilins, although certain differences in filamentous actin (F-actin) binding sites were present. The activity of recombinant NcADF on heterologous actin was regulated in part by pH and the presence of inorganic phosphate. In addition, our data suggest a comparatively weak disassembly of F-actin by NcADF. Taken together, the data presented herein represent a contribution to the field towards the understanding of the role of ADF in N. caninum and a comparative analysis of ABPs in the phylum Apicomplexa.
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Affiliation(s)
- Luciana Baroni
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, s/n, 14040-930, Ribeirão Preto, SP, Brazil
| | - Luiz M Pereira
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, s/n, 14040-930, Ribeirão Preto, SP, Brazil
| | - Sutherland K Maciver
- Centre for Discovery Brain Sciences, Biomedical Sciences, Edinburgh Medical School, University of Edinburgh, Hugh Robson Building, George Square, Edinburgh, EH8 9XD, Scotland, United Kingdom
| | - Ana P Yatsuda
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Av. do Café, s/n, 14040-930, Ribeirão Preto, SP, Brazil.
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19
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Douglas RG, Nandekar P, Aktories JE, Kumar H, Weber R, Sattler JM, Singer M, Lepper S, Sadiq SK, Wade RC, Frischknecht F. Inter-subunit interactions drive divergent dynamics in mammalian and Plasmodium actin filaments. PLoS Biol 2018; 16:e2005345. [PMID: 30011270 PMCID: PMC6055528 DOI: 10.1371/journal.pbio.2005345] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 06/13/2018] [Indexed: 01/01/2023] Open
Abstract
Cell motility is essential for protozoan and metazoan organisms and typically relies on the dynamic turnover of actin filaments. In metazoans, monomeric actin polymerises into usually long and stable filaments, while some protozoans form only short and highly dynamic actin filaments. These different dynamics are partly due to the different sets of actin regulatory proteins and partly due to the sequence of actin itself. Here we probe the interactions of actin subunits within divergent actin filaments using a comparative dynamic molecular model and explore their functions using Plasmodium, the protozoan causing malaria, and mouse melanoma derived B16-F1 cells as model systems. Parasite actin tagged to a fluorescent protein (FP) did not incorporate into mammalian actin filaments, and rabbit actin-FP did not incorporate into parasite actin filaments. However, exchanging the most divergent region of actin subdomain 3 allowed such reciprocal incorporation. The exchange of a single amino acid residue in subdomain 2 (N41H) of Plasmodium actin markedly improved incorporation into mammalian filaments. In the parasite, modification of most subunit–subunit interaction sites was lethal, whereas changes in actin subdomains 1 and 4 reduced efficient parasite motility and hence mosquito organ penetration. The strong penetration defects could be rescued by overexpression of the actin filament regulator coronin. Through these comparative approaches we identified an essential and common contributor, subdomain 3, which drives the differential dynamic behaviour of two highly divergent eukaryotic actins in motile cells. Actin is one of the most abundant and conserved proteins across eukaryotes. Its ability to assemble from individual monomers into dynamic polymers is essential for many cellular functions, including division and motility. In most cells, actin is able to form long and stable filaments. However, an actin of the malaria-causing parasite Plasmodium, while having a very similar monomer structure to actins from other eukaryotes, forms only short and unstable filaments. These short and dynamic filaments are crucial in allowing the parasite to move very rapidly in tissue. Here we investigated the basis of these differences. We used molecular dynamics simulations of actin filaments to investigate the actin–actin interfaces in filaments from Plasmodium and rabbit. We next engineered parasites to express chimeric actins that contained different parts of rabbit and parasite actin and thereby identified actin residues important for parasite viability and progression across the life cycle. We could rescue the most prominent defect specifically with overexpression of the actin binding protein coronin. This suggests that the more stable actin harms the parasite and that coronin helps in recycling filaments. By screening the effects of actin chimeras in mammalian cells, we also identified regions that allow these different actins to efficiently interact with each other. Taken together, our results improve our understanding of the interactions required for actin to incorporate into filaments across divergent eukaryotes.
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Affiliation(s)
- Ross G. Douglas
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Prajwal Nandekar
- Molecular and Cellular Modeling, Heidelberg Institute for Theoretical Studies (HITS), Heidelberg, Germany
- Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
| | - Julia-Elisabeth Aktories
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Hirdesh Kumar
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
- Molecular and Cellular Modeling, Heidelberg Institute for Theoretical Studies (HITS), Heidelberg, Germany
| | - Rebekka Weber
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Julia M. Sattler
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Mirko Singer
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - Simone Lepper
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
| | - S. Kashif Sadiq
- Molecular and Cellular Modeling, Heidelberg Institute for Theoretical Studies (HITS), Heidelberg, Germany
| | - Rebecca C. Wade
- Molecular and Cellular Modeling, Heidelberg Institute for Theoretical Studies (HITS), Heidelberg, Germany
- Center for Molecular Biology (ZMBH), DKFZ-ZMBH Alliance, Heidelberg, Germany
- Interdisciplinary Center for Scientific Computing (IWR), Heidelberg, Germany
- * E-mail: (FF); (RCW)
| | - Friedrich Frischknecht
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Heidelberg, Germany
- * E-mail: (FF); (RCW)
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20
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Actin from the apicomplexan Neospora caninum (NcACT) has different isoforms in 2D electrophoresis. Parasitology 2018; 146:33-41. [PMID: 29871709 DOI: 10.1017/s0031182018000872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Apicomplexan parasites have unconventional actins that play a central role in important cellular processes such as apicoplast replication, motility of dense granules, endocytic trafficking and force generation for motility and host cell invasion. In this study, we investigated the actin of the apicomplexan Neospora caninum - a parasite associated with infectious abortion and neonatal mortality in livestock. Neospora caninum actin was detected and identified in two bands by one-dimensional (1D) western blot and in nine spots by the 2D technique. The mass spectrometry data indicated that N. caninum has at least nine different actin isoforms, possibly caused by post-translational modifications. In addition, the C4 pan-actin antibody detected specifically actin in N. caninum cellular extract. Extracellular N. caninum tachyzoites were treated with toxins that act on actin, jasplakinolide and cytochalasin D. Both substances altered the peripheric cytoplasmic localization of actin on tachyzoites. Our findings add complexity to the study of the apicomplexan actin in cellular processes, since the multiple functions of this important protein might be regulated by mechanisms involving post-translational modifications.
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21
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Abstract
In the protozoan parasite Toxoplasma gondii, protein kinases have been shown to play key roles in regulating parasite motility, invasion, replication, egress, and survival within the host. The tyrosine kinase-like (TKL) family of proteins are an unexplored set of kinases in Toxoplasma. Of the eight annotated TKLs in the Toxoplasma genome, a recent genome-wide loss-of-function screen showed that six are important for tachyzoite fitness. By utilizing an endogenous tagging approach, we showed that these six T. gondii TKLs (TgTKLs) localize to various subcellular compartments, including the nucleus, the cytosol, the inner membrane complex, and the Golgi apparatus. To gain insight into the function of TKLs in Toxoplasma, we first characterized TgTKL1, which contains the plant-like enhanced disease resistance 1 (EDR1) domain and localizes to the nucleus. TgTKL1 knockout parasites displayed significant defects in progression through the lytic cycle; we show that the defects were due to specific impairment of host cell attachment. Transcriptomics analysis identified over 200 genes of diverse functions that were differentially expressed in TgTKL1 knockout parasites. Importantly, numerous genes implicated in host cell attachment and invasion were among those most significantly downregulated, resulting in defects in microneme secretion and processing. Significantly, all of the mice inoculated intraperitoneally with TgTKL1 knockout parasites survived the infection, suggesting that TgTKL1 plays an essential role in acute toxoplasmosis. Together, these findings suggest that TgTKL1 mediates a signaling pathway that regulates the expression of multiple factors required for parasite virulence, underscoring the potential of this kinase as a novel therapeutic target. Toxoplasma gondii is a protozoan parasite that can cause chronic and life-threatening disease in mammals; new drugs are greatly needed for treatment. One attractive group of drug targets consists of parasite kinases containing unique features that distinguish them from host proteins. In this report, we identify and characterize a previously unstudied kinase, TgTKL1, that localizes to the nucleus and contains a domain architecture unique to plants and protozoa. By disrupting TgTKL1, we showed that this kinase is required for the proper expression of hundreds of genes, including many that are required for the parasite to gain entry into the host cell. Specifically, parasites lacking TgTKL1 have defects in host cell attachment, resulting in impaired growth in vitro and a complete loss of virulence in mice. This report provides insight into the importance of the parasite tyrosine kinase-like kinases and establishes TgTKL1 as a novel and essential virulence factor in Toxoplasma.
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22
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Tardieux I, Baum J. Reassessing the mechanics of parasite motility and host-cell invasion. J Cell Biol 2017; 214:507-15. [PMID: 27573462 PMCID: PMC5004448 DOI: 10.1083/jcb.201605100] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 08/09/2016] [Indexed: 12/20/2022] Open
Abstract
The capacity to migrate is fundamental to multicellular and single-celled life. Apicomplexan parasites, an ancient protozoan clade that includes malaria parasites (Plasmodium) and Toxoplasma, achieve remarkable speeds of directional cell movement. This rapidity is achieved via a divergent actomyosin motor system, housed within a narrow compartment that lies underneath the length of the parasite plasma membrane. How this motor functions at a mechanistic level during motility and host cell invasion is a matter of debate. Here, we integrate old and new insights toward refining the current model for the function of this motor with the aim of revitalizing interest in the mechanics of how these deadly pathogens move.
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Affiliation(s)
- Isabelle Tardieux
- Institute of Advanced BioSciences, Institut National de la Santé et de la Recherche Médicale U1209, Centre National de la Recherche Scientifique UMR 5309, Université Grenoble Alpes, 38000, Grenoble, France
| | - Jake Baum
- Department of Life Sciences, Imperial College London, London SW7 2AZ, England, UK
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23
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Periz J, Whitelaw J, Harding C, Gras S, Del Rosario Minina MI, Latorre-Barragan F, Lemgruber L, Reimer MA, Insall R, Heaslip A, Meissner M. Toxoplasma gondii F-actin forms an extensive filamentous network required for material exchange and parasite maturation. eLife 2017; 6:e24119. [PMID: 28322189 PMCID: PMC5375643 DOI: 10.7554/elife.24119] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 03/09/2017] [Indexed: 01/14/2023] Open
Abstract
Apicomplexan actin is important during the parasite's life cycle. Its polymerization kinetics are unusual, permitting only short, unstable F-actin filaments. It has not been possible to study actin in vivo and so its physiological roles have remained obscure, leading to models distinct from conventional actin behaviour. Here a modified version of the commercially available actin-chromobody was tested as a novel tool for visualising F-actin dynamics in Toxoplasma gondii. Cb labels filamentous actin structures within the parasite cytosol and labels an extensive F-actin network that connects parasites within the parasitophorous vacuole and allows vesicles to be exchanged between parasites. In the absence of actin, parasites lack a residual body and inter-parasite connections and grow in an asynchronous and disorganized manner. Collectively, these data identify new roles for actin in the intracellular phase of the parasites lytic cycle and provide a robust new tool for imaging parasitic F-actin dynamics.
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Affiliation(s)
- Javier Periz
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Jamie Whitelaw
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Clare Harding
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Simon Gras
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Mario Igor Del Rosario Minina
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Fernanda Latorre-Barragan
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Leandro Lemgruber
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Madita Alice Reimer
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, United Kingdom
| | - Robert Insall
- Cancer Research United Kingdom Beatson Institute, Bearsden, United Kingdom
| | - Aoife Heaslip
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, United States
| | - Markus Meissner
- Wellcome Centre for Molecular Parasitology, Institute of Infection, Immunity & Inflammation, University of Glasgow, Glasgow, United Kingdom
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Stadler RV, White LA, Hu K, Helmke BP, Guilford WH. Direct measurement of cortical force generation and polarization in a living parasite. Mol Biol Cell 2017; 28:1912-1923. [PMID: 28209732 PMCID: PMC5541842 DOI: 10.1091/mbc.e16-07-0518] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 01/19/2017] [Accepted: 02/10/2017] [Indexed: 02/04/2023] Open
Abstract
Apicomplexa is a large phylum of intracellular parasites that are notable for the diseases they cause, including toxoplasmosis, malaria, and cryptosporidiosis. A conserved motile system is critical to their life cycles and drives directional gliding motility between cells, as well as invasion of and egress from host cells. However, our understanding of this system is limited by a lack of measurements of the forces driving parasite motion. We used a laser trap to measure the function of the motility apparatus of living Toxoplasma gondii by adhering a microsphere to the surface of an immobilized parasite. Motion of the microsphere reflected underlying forces exerted by the motile apparatus. We found that force generated at the parasite surface begins with no preferential directionality but becomes directed toward the rear of the cell after a period of time. The transition from nondirectional to directional force generation occurs on spatial intervals consistent with the lateral periodicity of structures associated with the membrane pellicle and is influenced by the kinetics of actin filament polymerization and cytoplasmic calcium. A lysine methyltransferase regulates both the magnitude and polarization of the force. Our work provides a novel means to dissect the motile mechanisms of these pathogens.
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Affiliation(s)
- Rachel V Stadler
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908
| | - Lauren A White
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908
| | - Ke Hu
- Department of Biology, Indiana University, Bloomington, IN 47405
| | - Brian P Helmke
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908
| | - William H Guilford
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908
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Whitelaw JA, Latorre-Barragan F, Gras S, Pall GS, Leung JM, Heaslip A, Egarter S, Andenmatten N, Nelson SR, Warshaw DM, Ward GE, Meissner M. Surface attachment, promoted by the actomyosin system of Toxoplasma gondii is important for efficient gliding motility and invasion. BMC Biol 2017; 15:1. [PMID: 28100223 PMCID: PMC5242020 DOI: 10.1186/s12915-016-0343-5] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 12/10/2016] [Indexed: 12/17/2022] Open
Abstract
Background Apicomplexan parasites employ a unique form of movement, termed gliding motility, in order to invade the host cell. This movement depends on the parasite’s actomyosin system, which is thought to generate the force during gliding. However, recent evidence questions the exact molecular role of this system, since mutants for core components of the gliding machinery, such as parasite actin or subunits of the MyoA-motor complex (the glideosome), remain motile and invasive, albeit at significantly reduced efficiencies. While compensatory mechanisms and unusual polymerisation kinetics of parasite actin have been evoked to explain these findings, the actomyosin system could also play a role distinct from force production during parasite movement. Results In this study, we compared the phenotypes of different mutants for core components of the actomyosin system in Toxoplasma gondii to decipher their exact role during gliding motility and invasion. We found that, while some phenotypes (apicoplast segregation, host cell egress, dense granule motility) appeared early after induction of the act1 knockout and went to completion, a small percentage of the parasites remained capable of motility and invasion well past the point at which actin levels were undetectable. Those act1 conditional knockout (cKO) and mlc1 cKO that continue to move in 3D do so at speeds similar to wildtype parasites. However, these mutants are virtually unable to attach to a collagen-coated substrate under flow conditions, indicating an important role for the actomyosin system of T. gondii in the formation of attachment sites. Conclusion We demonstrate that parasite actin is essential during the lytic cycle and cannot be compensated by other molecules. Our data suggest a conventional polymerisation mechanism in vivo that depends on a critical concentration of G-actin. Importantly, we demonstrate that the actomyosin system of the parasite functions in attachment to the surface substrate, and not necessarily as force generator. Electronic supplementary material The online version of this article (doi:10.1186/s12915-016-0343-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jamie A Whitelaw
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Fernanda Latorre-Barragan
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Simon Gras
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Gurman S Pall
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Jacqueline M Leung
- Department of Biology, Indiana University, Bloomington, Myers Hall 240, 915 E 3rd St Bloomington, Bloomington, IN, 47405, USA.,University of Vermont, Department of Microbiology and Molecular Genetics, College of Medicine, Burlington, VT, 05405, USA
| | - Aoife Heaslip
- University of Vermont, Department of Molecular Physiology and Biophysics Burlington, Vermont, 05405, USA
| | - Saskia Egarter
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Nicole Andenmatten
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK
| | - Shane R Nelson
- University of Vermont, Department of Molecular Physiology and Biophysics Burlington, Vermont, 05405, USA
| | - David M Warshaw
- University of Vermont, Department of Molecular Physiology and Biophysics Burlington, Vermont, 05405, USA
| | - Gary E Ward
- University of Vermont, Department of Microbiology and Molecular Genetics, College of Medicine, Burlington, VT, 05405, USA
| | - Markus Meissner
- Wellcome Trust Centre For Molecular Parasitology, Institute of Infection, Immunity & Inflammation, Glasgow Biomedical Research Centre, University of Glasgow, 120 University Place, Glasgow, G12 8TA, UK.
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New cell motility model observed in parasitic cnidarian Sphaerospora molnari (Myxozoa:Myxosporea) blood stages in fish. Sci Rep 2016; 6:39093. [PMID: 27982057 PMCID: PMC5159882 DOI: 10.1038/srep39093] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 11/17/2016] [Indexed: 12/31/2022] Open
Abstract
Cellular motility is essential for microscopic parasites, it is used to reach the host, migrate through tissues, or evade host immune reactions. Many cells employ an evolutionary conserved motor protein– actin, to crawl or glide along a substrate. We describe the peculiar movement of Sphaerospora molnari, a myxozoan parasite with proliferating blood stages in its host, common carp. Myxozoa are highly adapted parasitic cnidarians alternately infecting vertebrates and invertebrates. S. molnari blood stages (SMBS) have developed a unique “dancing” behaviour, using the external membrane as a motility effector to rotate and move the cell. SMBS movement is exceptionally fast compared to other myxozoans, non-directional and constant. The movement is based on two cytoplasmic actins that are highly divergent from those of other metazoans. We produced a specific polyclonal actin antibody for the staining and immunolabelling of S. molnari’s microfilaments since we found that neither commercial antibodies nor phalloidin recognised the protein or microfilaments. We show the in situ localization of this actin in the parasite and discuss the importance of this motility for evasion from the cellular host immune response in vitro. This new type of motility holds key insights into the evolution of cellular motility and associated proteins.
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Wetzel DM, Rhodes EL, Li S, McMahon-Pratt D, Koleske AJ. The Src kinases Hck, Fgr and Lyn activate Arg to facilitate IgG-mediated phagocytosis and Leishmania infection. J Cell Sci 2016; 129:3130-43. [PMID: 27358479 DOI: 10.1242/jcs.185595] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Accepted: 06/23/2016] [Indexed: 12/19/2022] Open
Abstract
Leishmaniasis is a devastating disease that disfigures or kills nearly two million people each year. Establishment and persistence of infection by the obligate intracellular parasite Leishmania requires repeated uptake by macrophages and other phagocytes. Therefore, preventing uptake could be a novel therapeutic strategy for leishmaniasis. Amastigotes, the life cycle stage found in the human host, bind Fc receptors and enter macrophages primarily through immunoglobulin-mediated phagocytosis. However, the host machinery that mediates amastigote uptake is poorly understood. We have previously shown that the Arg (also known as Abl2) non-receptor tyrosine kinase facilitates L. amazonensis amastigote uptake by macrophages. Using small-molecule inhibitors and primary macrophages lacking specific Src family kinases, we now demonstrate that the Hck, Fgr and Lyn kinases are also necessary for amastigote uptake by macrophages. Src-mediated Arg activation is required for efficient uptake. Interestingly, the dual Arg and Src kinase inhibitor bosutinib, which is approved to treat cancer, not only decreases amastigote uptake, but also significantly reduces disease severity and parasite burden in Leishmania-infected mice. Our results suggest that leishmaniasis could potentially be treated with host-cell-active agents such as kinase inhibitors.
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Affiliation(s)
- Dawn M Wetzel
- Department of Pediatrics, Yale University, New Haven, CT 06520, USA
| | - Emma L Rhodes
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Shaoguang Li
- Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Diane McMahon-Pratt
- Department of Epidemiology of Microbial Disease, Yale School of Public Health, New Haven, CT 06520, USA
| | - Anthony J Koleske
- Department of Molecular Biochemistry and Biophysics, Yale University, CT 06520, USA Department of Neuroscience, Yale University, New Haven, CT 06520, USA
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28
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Kissmehl R, Sehring IM, Wagner E, Plattner H. Immunolocalization of Actin in Paramecium Cells. J Histochem Cytochem 2016; 52:1543-59. [PMID: 15557210 DOI: 10.1369/jhc.4a6379.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have selected a conserved immunogenic region from several actin genes of Paramecium, recently cloned in our laboratory, to prepare antibodies for Western blots and immunolocalization. According to cell fractionation analysis, most actin is structure-bound. Immunofluorescence shows signal enriched in the cell cortex, notably around ciliary basal bodies (identified by anti-centrin antibodies), as well as around the oral cavity, at the cytoproct and in association with vacuoles (phagosomes) up to several μm in size. Subtle strands run throughout the cell body. Postembedding immunogold labeling/EM analysis shows that actin in the cell cortex emanates, together with the infraciliary lattice, from basal bodies to around trichocyst tips. Label was also enriched around vacuoles and vesicles of different size including “discoidal” vesicles that serve the formation of new phagosomes. By all methods used, we show actin in cilia. Although none of the structurally well-defined filament systems in Paramecium are exclusively formed by actin, actin does display some ordered, though not very conspicuous, arrays throughout the cell. F-actin may somehow serve vesicle trafficking and as a cytoplasmic scaffold. This is particularly supported by the postembedding/EM labeling analysis we used, which would hardly allow for any large-scale redistribution during preparation.
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Affiliation(s)
- Roland Kissmehl
- Department of Biology, University of Konstanz, PO Box 5560, 78457 Konstanz, Germany
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Sato Y, Hliscs M, Dunst J, Goosmann C, Brinkmann V, Montagna GN, Matuschewski K. Comparative Plasmodium gene overexpression reveals distinct perturbation of sporozoite transmission by profilin. Mol Biol Cell 2016; 27:2234-44. [PMID: 27226484 PMCID: PMC4945141 DOI: 10.1091/mbc.e15-10-0734] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 05/16/2016] [Indexed: 12/27/2022] Open
Abstract
The roles of vital genes, such as those of G-actin–binding proteins, in malaria parasites are underexplored. Overexpression of Plasmodium profilin perturbs actin dynamics only in sporozoites. Strict actin regulation is particularly important for malaria transmission. Mapping of phenotypes can be done by comparative Plasmodium gene overexpression. Plasmodium relies on actin-based motility to migrate from the site of infection and invade target cells. Using a substrate-dependent gliding locomotion, sporozoites are able to move at fast speed (1–3 μm/s). This motility relies on a minimal set of actin regulatory proteins and occurs in the absence of detectable filamentous actin (F-actin). Here we report an overexpression strategy to investigate whether perturbations of F-actin steady-state levels affect gliding locomotion and host invasion. We selected two vital Plasmodium berghei G-actin–binding proteins, C-CAP and profilin, in combination with three stage-specific promoters and mapped the phenotypes afforded by overexpression in all three extracellular motile stages. We show that in merozoites and ookinetes, additional expression does not impair life cycle progression. In marked contrast, overexpression of C-CAP and profilin in sporozoites impairs circular gliding motility and salivary gland invasion. The propensity for productive motility correlates with actin accumulation at the parasite tip, as revealed by combinations of an actin-stabilizing drug and transgenic parasites. Strong expression of profilin, but not C-CAP, resulted in complete life cycle arrest. Comparative overexpression is an alternative experimental genetic strategy to study essential genes and reveals effects of regulatory imbalances that are not uncovered from deletion-mutant phenotyping.
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Affiliation(s)
- Yuko Sato
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany Infectious Diseases Interdisciplinary Research Group, Singapore-Massachusetts Institute of Technology Alliance for Research and Technology, 138602 Singapore
| | - Marion Hliscs
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany School of BioSciences, University of Melbourne, Parkville, 3010 Victoria, Australia
| | - Josefine Dunst
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Christian Goosmann
- Imaging Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany
| | - Volker Brinkmann
- Imaging Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany
| | - Georgina N Montagna
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany Departamento de Microbiologia, Immunologia e Parasitologia, Universidade Federal de São Paulo, 04039-032 São Paulo, Brazil
| | - Kai Matuschewski
- Parasitology Unit, Max Planck Institute for Infection Biology, 10117 Berlin, Germany Institute of Biology, Humboldt University, 10117 Berlin, Germany
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30
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Quadt KA, Streichfuss M, Moreau CA, Spatz JP, Frischknecht F. Coupling of Retrograde Flow to Force Production During Malaria Parasite Migration. ACS NANO 2016; 10:2091-2102. [PMID: 26792112 DOI: 10.1021/acsnano.5b06417] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Migration of malaria parasites is powered by a myosin motor that moves actin filaments, which in turn link to adhesive proteins spanning the plasma membrane. The retrograde flow of these adhesins appears to be coupled to forward locomotion. However, the contact dynamics between the parasite and the substrate as well as the generation of forces are complex and their relation to retrograde flow is unclear. Using optical tweezers we found retrograde flow rates up to 15 μm/s contrasting with parasite average speeds of 1-2 μm/s. We found that a surface protein, TLP, functions in reducing retrograde flow for the buildup of adhesive force and that actin dynamics appear optimized for the generation of force but not for maximizing the speed of retrograde flow. These data uncover that TLP acts by modulating actin dynamics or actin filament organization and couples retrograde flow to force production in malaria parasites.
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Affiliation(s)
- Katharina A Quadt
- Integrative Parasitology, Center for Infectious Diseases, University of Heidelberg Medical School , Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Martin Streichfuss
- Integrative Parasitology, Center for Infectious Diseases, University of Heidelberg Medical School , Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
- University of Heidelberg , Department of Biophysical Chemistry and Max Planck Institute for Intelligent Systems, Department of New Materials and Biosystems, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Catherine A Moreau
- Integrative Parasitology, Center for Infectious Diseases, University of Heidelberg Medical School , Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Joachim P Spatz
- University of Heidelberg , Department of Biophysical Chemistry and Max Planck Institute for Intelligent Systems, Department of New Materials and Biosystems, Heisenbergstr. 3, 70569 Stuttgart, Germany
| | - Friedrich Frischknecht
- Integrative Parasitology, Center for Infectious Diseases, University of Heidelberg Medical School , Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
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31
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Gliding motility in apicomplexan parasites. Semin Cell Dev Biol 2015; 46:135-42. [DOI: 10.1016/j.semcdb.2015.09.020] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/25/2015] [Indexed: 11/22/2022]
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Abstract
Toxoplasmosis is the clinical and pathological consequence of acute infection with the obligate intracellular apicomplexan parasite Toxoplasma gondii. Symptoms result from tissue destruction that accompanies lytic parasite growth. This review updates current understanding of the host cell invasion, parasite replication, and eventual egress that constitute the lytic cycle, as well as the ways T. gondii manipulates host cells to ensure its survival. Since the publication of a previous iteration of this review 15 years ago, important advances have been made in our molecular understanding of parasite growth and mechanisms of host cell egress, and knowledge of the parasite's manipulation of the host has rapidly progressed. Here we cover molecular advances and current conceptual frameworks that include each of these topics, with an eye to what may be known 15 years from now.
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Affiliation(s)
- Ira J Blader
- Department of Microbiology and Immunology, University at Buffalo, Buffalo, New York 14127;
| | - Bradley I Coleman
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467; , ,
| | - Chun-Ti Chen
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467; , ,
| | - Marc-Jan Gubbels
- Department of Biology, Boston College, Chestnut Hill, Massachusetts 02467; , ,
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Olshina MA, Angrisano F, Marapana DS, Riglar DT, Bane K, Wong W, Catimel B, Yin MX, Holmes AB, Frischknecht F, Kovar DR, Baum J. Plasmodium falciparum coronin organizes arrays of parallel actin filaments potentially guiding directional motility in invasive malaria parasites. Malar J 2015; 14:280. [PMID: 26187846 PMCID: PMC4506582 DOI: 10.1186/s12936-015-0801-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 07/04/2015] [Indexed: 12/20/2022] Open
Abstract
Background Gliding motility in Plasmodium parasites, the aetiological agents of malaria disease, is mediated by
an actomyosin motor anchored in the outer pellicle of the motile cell. Effective motility is dependent on a parasite myosin motor and turnover of dynamic parasite actin filaments. To date, however, the basis for directional motility is not known. Whilst myosin is very likely orientated as a result of its anchorage within the parasite, how actin filaments are orientated to facilitate directional force generation remains unexplained. In addition, recent evidence has questioned the linkage between actin filaments and secreted surface antigens leaving the way by which motor force is transmitted to the extracellular milieu unknown. Malaria parasites possess a markedly reduced repertoire of actin regulators, among which few are predicted to interact with filamentous (F)-actin directly. One of these, PF3D7_1251200, shows strong homology to the coronin family of actin-filament binding proteins, herein referred to as PfCoronin. Methods Here the N terminal beta propeller domain of PfCoronin (PfCor-N) was expressed to assess its ability to bind and bundle pre-formed actin filaments by sedimentation assay, total internal reflection fluorescence (TIRF) microscopy and confocal imaging as well as to explore its ability to bind phospholipids. In parallel a tagged PfCoronin line in Plasmodium falciparum was generated to determine the cellular localization of the protein during asexual parasite development and blood-stage merozoite invasion. Results A combination of biochemical approaches demonstrated that the N-terminal beta-propeller domain of PfCoronin is capable of binding F-actin and facilitating formation of parallel filament bundles. In parasites, PfCoronin is expressed late in the asexual lifecycle and localizes to the pellicle region of invasive merozoites before and during erythrocyte entry. PfCoronin also associates strongly with membranes within the cell, likely mediated by interactions with phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2) at the plasma membrane. Conclusions These data suggest PfCoronin may fulfil a key role as the critical determinant of actin filament organization in the Plasmodium cell. This raises the possibility that macro-molecular organization of actin mediates directional motility in gliding parasites. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0801-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Maya A Olshina
- Infection and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
| | - Fiona Angrisano
- Infection and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
| | - Danushka S Marapana
- Infection and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
| | - David T Riglar
- Infection and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia. .,Department of Systems Biology, Harvard Medical School, 200 Longwood Ave WAB 536, Boston, MA, 02115, USA.
| | - Kartik Bane
- Department of Infectious Diseases, University of Heidelberg Medical School, Heidelberg, Germany.
| | - Wilson Wong
- Infection and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia.
| | - Bruno Catimel
- Ludwig Institute for Cancer Research, Melbourne Tumour Biology Branch, Royal Melbourne Hospital, Parkville, VIC, 3052, Australia. .,Systems Biology and Personalised Medicine Division, Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia.
| | - Meng-Xin Yin
- School of Chemistry, Bio21 Institute, University of Melbourne, Parkville, VIC, 3010, Australia.
| | - Andrew B Holmes
- School of Chemistry, Bio21 Institute, University of Melbourne, Parkville, VIC, 3010, Australia.
| | - Friedrich Frischknecht
- Department of Infectious Diseases, University of Heidelberg Medical School, Heidelberg, Germany.
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, USA. .,Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, USA.
| | - Jake Baum
- Infection and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, 3052, Australia. .,Department of Medical Biology, University of Melbourne, Parkville, VIC, 3052, Australia. .,Department of Life Sciences, Imperial College London, Sir Alexander Fleming Building, Level 6, South Kensington, London, SW72AZ, UK.
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Haase S, Zimmermann D, Olshina MA, Wilkinson M, Fisher F, Tan YH, Stewart RJ, Tonkin CJ, Wong W, Kovar DR, Baum J. Disassembly activity of actin-depolymerizing factor (ADF) is associated with distinct cellular processes in apicomplexan parasites. Mol Biol Cell 2015; 26:3001-12. [PMID: 26157165 PMCID: PMC4551315 DOI: 10.1091/mbc.e14-10-1427] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Accepted: 06/30/2015] [Indexed: 12/15/2022] Open
Abstract
Complementation of a conditional KO of actin-depolymerizing factor (ADF) in Toxoplasma gondii demonstrates that ADF-dependent actin filament disassembly is essential for parasite development but not for cell motility. Furthermore, trans-genera complementation highlights genus-specific coevolution between ADF proteins and their native actins. Proteins of the actin-depolymerizing factor (ADF)/cofilin family have been shown to be crucial for the motility and survival of apicomplexan parasites. However, the mechanisms by which ADF proteins fulfill their function remain poorly understood. In this study, we investigate the comparative activities of ADF proteins from Toxoplasma gondii and Plasmodium falciparum, the human malaria parasite, using a conditional T. gondii ADF-knockout line complemented with ADF variants from either species. We show that P. falciparum ADF1 can fully restore native TgADF activity, demonstrating functional conservation between parasites. Strikingly, mutation of a key basic residue (Lys-72), previously implicated in disassembly in PfADF1, had no detectable phenotypic effect on parasite growth, motility, or development. In contrast, organelle segregation was severely impaired when complementing with a TgADF mutant lacking the corresponding residue (Lys-68). Biochemical analyses of each ADF protein confirmed the reduced ability of lysine mutants to mediate actin depolymerization via filament disassembly although not severing, in contrast to previous reports. These data suggest that actin filament disassembly is essential for apicomplexan parasite development but not for motility, as well as pointing to genus-specific coevolution between ADF proteins and their native actin.
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Affiliation(s)
- Silvia Haase
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Dennis Zimmermann
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Maya A Olshina
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Mark Wilkinson
- Department of Life Sciences, Imperial College, London SW7 2AZ, United Kingdom
| | - Fabio Fisher
- Department of Life Sciences, Imperial College, London SW7 2AZ, United Kingdom
| | - Yan Hong Tan
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Rebecca J Stewart
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Christopher J Tonkin
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - Wilson Wong
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia
| | - David R Kovar
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60637
| | - Jake Baum
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia Department of Life Sciences, Imperial College, London SW7 2AZ, United Kingdom
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35
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Unconventional actins and actin-binding proteins in human protozoan parasites. Int J Parasitol 2015; 45:435-47. [DOI: 10.1016/j.ijpara.2015.01.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 12/19/2014] [Accepted: 01/27/2015] [Indexed: 12/11/2022]
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36
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Liu F, Wu D, Wu X, Chen K. Analyses of the cell mechanical damage during microinjection. SOFT MATTER 2015; 11:1434-1442. [PMID: 25584666 DOI: 10.1039/c4sm02773f] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The microinjection is an essential technique to introduce foreign materials into biological cells. The soft cell is inevitably ruptured by the microinjector during microinjection. We discuss the way to reduce the mechanical damage by analyzing the control parameters during microinjection. The computational model is developed with the dissipative particle dynamics to simulate the soft mechanical properties of biological cells. The cell model contains the membrane networks, the internal cytoskeleton, crosslink proteins, motors and their functions. The weak power law rheology verifies our computational model. The number of ruptured bonds is used to describe the extent of the mechanical damage that the cell experiences during microinjection. Some experiments are conducted on the Zebrafish embryos. Both the simulation works and experimental results show that the size, shape of the microinjector tip, and the injection velocity have a significant influence on the cell damage. A small, sharp microinjector with a high velocity can reduce the mechanical damage.
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Affiliation(s)
- Fei Liu
- State Key Laboratory of Mechanical Transmission, Department of Mechanical Engineering, Chongqing University, Room 315-2, Teaching Building 7, Chongqing, 400044, China.
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37
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Hliscs M, Millet C, Dixon MW, Siden-Kiamos I, McMillan P, Tilley L. Organization and function of an actin cytoskeleton inPlasmodium falciparumgametocytes. Cell Microbiol 2014; 17:207-25. [DOI: 10.1111/cmi.12359] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 08/16/2014] [Accepted: 08/19/2014] [Indexed: 01/05/2023]
Affiliation(s)
- Marion Hliscs
- Department of Biochemistry and Molecular Biology; Bio21 Molecular Science and Biotechnology Institute; Melbourne Vic. 3010 Australia
- Australian Research Council Centre of Excellence for Coherent X-ray Science; The University of Melbourne; Melbourne Vic. 3010 Australia
- School of Botany; The University of Melbourne; Melbourne Vic. 3010 Australia
| | - Coralie Millet
- Department of Biochemistry and Molecular Biology; Bio21 Molecular Science and Biotechnology Institute; Melbourne Vic. 3010 Australia
- Australian Research Council Centre of Excellence for Coherent X-ray Science; The University of Melbourne; Melbourne Vic. 3010 Australia
| | - Matthew W. Dixon
- Department of Biochemistry and Molecular Biology; Bio21 Molecular Science and Biotechnology Institute; Melbourne Vic. 3010 Australia
- Australian Research Council Centre of Excellence for Coherent X-ray Science; The University of Melbourne; Melbourne Vic. 3010 Australia
| | - Inga Siden-Kiamos
- Institute of Molecular Biology and Biotechnology; Foundation for Research and Technology; Hellas, 700 13 Heraklion Crete Greece
| | - Paul McMillan
- Department of Biochemistry and Molecular Biology; Bio21 Molecular Science and Biotechnology Institute; Melbourne Vic. 3010 Australia
- The Biological Optical Microscopy Platform; The University of Melbourne; Melbourne Vic. 3010 Australia
| | - Leann Tilley
- Department of Biochemistry and Molecular Biology; Bio21 Molecular Science and Biotechnology Institute; Melbourne Vic. 3010 Australia
- Australian Research Council Centre of Excellence for Coherent X-ray Science; The University of Melbourne; Melbourne Vic. 3010 Australia
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38
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Salamun J, Kallio JP, Daher W, Soldati-Favre D, Kursula I. Structure of Toxoplasma gondii coronin, an actin-binding protein that relocalizes to the posterior pole of invasive parasites and contributes to invasion and egress. FASEB J 2014; 28:4729-47. [PMID: 25114175 DOI: 10.1096/fj.14-252569] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Coronins are involved in the regulation of actin dynamics in a multifaceted way, participating in cell migration and vesicular trafficking. Apicomplexan parasites, which exhibit an actin-dependent gliding motility that is essential for traversal through tissues, as well as invasion of and egress from host cells, express only a single coronin, whereas higher eukaryotes possess several isoforms. We set out to characterize the 3-D structure, biochemical function, subcellular localization, and genetic ablation of Toxoplasma gondii coronin (TgCOR), to shed light on its biological role. A combination of X-ray crystallography, small-angle scattering of X-rays, and light scattering revealed the atomic structure of the conserved WD40 domain and the dimeric arrangement of the full-length protein. TgCOR binds to F-actin and increases the rate and extent of actin polymerization. In vivo, TgCOR relocalizes transiently to the posterior pole of motile and invading parasites, independent of actin dynamics, but concomitant to microneme secretory organelle discharge. TgCOR contributes to, but is not essential for, invasion and egress. Taken together, our data point toward a role for TgCOR in stabilizing newly formed, short filaments and F-actin cross-linking, as well as functions linked to endocytosis and recycling of membranes.
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Affiliation(s)
- Julien Salamun
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Juha P Kallio
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research and German Electron Synchrotron (DESY), Hamburg, Germany; and
| | - Wassim Daher
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland;
| | - Inari Kursula
- Centre for Structural Systems Biology, Helmholtz Centre for Infection Research and German Electron Synchrotron (DESY), Hamburg, Germany; and Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
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39
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Tang Q, Andenmatten N, Hortua Triana MA, Deng B, Meissner M, Moreno SNJ, Ballif BA, Ward GE. Calcium-dependent phosphorylation alters class XIVa myosin function in the protozoan parasite Toxoplasma gondii. Mol Biol Cell 2014; 25:2579-91. [PMID: 24989796 PMCID: PMC4148248 DOI: 10.1091/mbc.e13-11-0648] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Myosin A, an unconventional class XIV myosin of the protozoan parasite Toxoplasma gondii, undergoes calcium-dependent phosphorylation, providing a mechanism by which the parasite can regulate motility-based processes such as escape from the infected host cell at the end of the parasite's lytic cycle. Class XIVa myosins comprise a unique group of myosin motor proteins found in apicomplexan parasites, including those that cause malaria and toxoplasmosis. The founding member of the class XIVa family, Toxoplasma gondii myosin A (TgMyoA), is a monomeric unconventional myosin that functions at the parasite periphery to control gliding motility, host cell invasion, and host cell egress. How the motor activity of TgMyoA is regulated during these critical steps in the parasite's lytic cycle is unknown. We show here that a small-molecule enhancer of T. gondii motility and invasion (compound 130038) causes an increase in parasite intracellular calcium levels, leading to a calcium-dependent increase in TgMyoA phosphorylation. Mutation of the major sites of phosphorylation altered parasite motile behavior upon compound 130038 treatment, and parasites expressing a nonphosphorylatable mutant myosin egressed from host cells more slowly in response to treatment with calcium ionophore. These data demonstrate that TgMyoA undergoes calcium-dependent phosphorylation, which modulates myosin-driven processes in this important human pathogen.
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Affiliation(s)
- Qing Tang
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405
| | - Nicole Andenmatten
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Miryam A Hortua Triana
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Bin Deng
- Vermont Genetics Network Proteomics Facility, University of Vermont, Burlington, VT 05405 Department of Biology, University of Vermont, Burlington, VT 05405
| | - Markus Meissner
- Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Silvia N J Moreno
- Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602
| | - Bryan A Ballif
- Department of Biology, University of Vermont, Burlington, VT 05405
| | - Gary E Ward
- Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405
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40
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Jacot D, Frénal K, Marq JB, Sharma P, Soldati-Favre D. Assessment of phosphorylation inToxoplasmaglideosome assembly and function. Cell Microbiol 2014; 16:1518-32. [DOI: 10.1111/cmi.12307] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 04/16/2014] [Indexed: 01/10/2023]
Affiliation(s)
- Damien Jacot
- Department of Microbiology & Molecular Medicine; CMU/University of Geneva; Rue Michel-Servet 1 CH-1211 Geneva 4 Switzerland
| | - Karine Frénal
- Department of Microbiology & Molecular Medicine; CMU/University of Geneva; Rue Michel-Servet 1 CH-1211 Geneva 4 Switzerland
| | - Jean-Baptiste Marq
- Department of Microbiology & Molecular Medicine; CMU/University of Geneva; Rue Michel-Servet 1 CH-1211 Geneva 4 Switzerland
| | - Pushkar Sharma
- Eukaryotic Gene Expression Laboratory; National Institute of Immunology; New Delhi 110067 India
| | - Dominique Soldati-Favre
- Department of Microbiology & Molecular Medicine; CMU/University of Geneva; Rue Michel-Servet 1 CH-1211 Geneva 4 Switzerland
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41
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Vahokoski J, Bhargav SP, Desfosses A, Andreadaki M, Kumpula EP, Martinez SM, Ignatev A, Lepper S, Frischknecht F, Sidén-Kiamos I, Sachse C, Kursula I. Structural differences explain diverse functions of Plasmodium actins. PLoS Pathog 2014; 10:e1004091. [PMID: 24743229 PMCID: PMC3990709 DOI: 10.1371/journal.ppat.1004091] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 03/11/2014] [Indexed: 11/18/2022] Open
Abstract
Actins are highly conserved proteins and key players in central processes in all eukaryotic cells. The two actins of the malaria parasite are among the most divergent eukaryotic actins and also differ from each other more than isoforms in any other species. Microfilaments have not been directly observed in Plasmodium and are presumed to be short and highly dynamic. We show that actin I cannot complement actin II in male gametogenesis, suggesting critical structural differences. Cryo-EM reveals that Plasmodium actin I has a unique filament structure, whereas actin II filaments resemble canonical F-actin. Both Plasmodium actins hydrolyze ATP more efficiently than α-actin, and unlike any other actin, both parasite actins rapidly form short oligomers induced by ADP. Crystal structures of both isoforms pinpoint several structural changes in the monomers causing the unique polymerization properties. Inserting the canonical D-loop to Plasmodium actin I leads to the formation of long filaments in vitro. In vivo, this chimera restores gametogenesis in parasites lacking actin II, suggesting that stable filaments are required for exflagellation. Together, these data underline the divergence of eukaryotic actins and demonstrate how structural differences in the monomers translate into filaments with different properties, implying that even eukaryotic actins have faced different evolutionary pressures and followed different paths for developing their polymerization properties. Malaria parasites have two actin isoforms, which are among the most divergent within the actin family that comprises highly conserved proteins, essential in all eukaryotic cells. In Plasmodium, actin is indispensable for motility and, thus, the infectivity of the deadly parasite. Yet, actin filaments have not been observed in vivo in these pathogens. Here, we show that the two Plasmodium actins differ from each other in both monomeric and filamentous form and that actin I cannot replace actin II during male gametogenesis. Whereas the major isoform actin I cannot form stable filaments alone, the mosquito-stage-specific actin II readily forms long filaments that have dimensions similar to canonical actins. A chimeric actin I mutant that forms long filaments in vitro also rescues gametogenesis in parasites lacking actin II. Both Plasmodium actins rapidly hydrolyze ATP and form short oligomers in the presence of ADP, which is a fundamental difference to all other actins characterized to date. Structural and functional differences in the two Plasmodium actin isoforms compared both to each other and to canonical actins reveal how the polymerization properties of eukaryotic actins have evolved along different avenues.
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Affiliation(s)
- Juha Vahokoski
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | | | - Ambroise Desfosses
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Heidelberg, Germany
| | - Maria Andreadaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology – Hellas, Heraklion, Crete, Greece
| | - Esa-Pekka Kumpula
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
- Centre for Structural Systems Biology; Helmholtz Centre for Infection Research and German Electron Synchrotron, Hamburg, Germany
| | | | - Alexander Ignatev
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - Simone Lepper
- Parasitology – Department of Infectious Diseases, University of Heidelberg Medical School, Heidelberg, Germany
| | - Friedrich Frischknecht
- Parasitology – Department of Infectious Diseases, University of Heidelberg Medical School, Heidelberg, Germany
| | - Inga Sidén-Kiamos
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology – Hellas, Heraklion, Crete, Greece
| | - Carsten Sachse
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, Heidelberg, Germany
| | - Inari Kursula
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
- Centre for Structural Systems Biology; Helmholtz Centre for Infection Research and German Electron Synchrotron, Hamburg, Germany
- * E-mail:
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42
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Abstract
Toxoplasma gondii is a highly successful parasite that infects approximately one-third of the human population and can cause fatal disease in immunocompromised individuals. Systemic parasite dissemination to organs such as the brain and eye is critical to pathogenesis. T. gondii can disseminate via the circulation, and both intracellular and extracellular modes of transport have been proposed. However, the processes by which extracellular tachyzoites adhere to and migrate across vascular endothelium under the conditions of rapidly flowing blood remain unknown. We used microfluidics and time-lapse fluorescence microscopy to examine the interactions between extracellular T. gondii and primary human endothelial cells under conditions of physiologic shear stress. Remarkably, tachyzoites adhered to and glided on human vascular endothelium under shear stress conditions. Compared to static conditions, shear stress enhanced T. gondii helical gliding, resulting in a significantly greater displacement, and increased the percentage of tachyzoites that invaded or migrated across the endothelium. The intensity of the shear forces (from 0.5 to 10 dynes/cm2) influenced both initial and sustained adhesion to endothelium. By examining tachyzoites deficient in the T. gondii adhesion protein MIC2, we found that MIC2 contributed to initial adhesion but was not required for adhesion strengthening. These data suggest that under fluidic conditions, T. gondii adhesion to endothelium may be mediated by a multistep cascade of interactions that is governed by unique combinations of adhesion molecules. This work provides novel information about tachyzoite interactions with vascular endothelium and contributes to our understanding of T. gondii dissemination in the infected host. Toxoplasma gondii is a global parasite pathogen that can cause fatal disease in immunocompromised individuals. An unresolved question is how the parasites circulate in the body to tissues to cause disease. T. gondii parasites are found in the bloodstream of infected animals and patients, and they have been shown to adhere to and cross the endothelial cells that line blood vessel walls. To investigate these interactions, we devised a microfluidic system to visualize parasites interacting with vascular endothelium under conditions similar to those found in the bloodstream. Interestingly, parasite migration was significantly influenced by the mechanical force of shear flow. Furthermore, we identified a role for the parasite surface protein MIC2 in the initial phase of adhesion. Our study is the first to document T. gondii interactions with endothelium under shear stress conditions and provides a foundation for future studies on the molecules that mediate parasite interaction with the vasculature.
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43
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Kan A, Tan YH, Angrisano F, Hanssen E, Rogers KL, Whitehead L, Mollard VP, Cozijnsen A, Delves MJ, Crawford S, Sinden RE, McFadden GI, Leckie C, Bailey J, Baum J. Quantitative analysis of Plasmodium ookinete motion in three dimensions suggests a critical role for cell shape in the biomechanics of malaria parasite gliding motility. Cell Microbiol 2014; 16:734-50. [PMID: 24612056 PMCID: PMC4286792 DOI: 10.1111/cmi.12283] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 01/22/2014] [Accepted: 02/13/2014] [Indexed: 11/28/2022]
Abstract
Motility is a fundamental part of cellular life and survival, including for Plasmodium parasites--single-celled protozoan pathogens responsible for human malaria. The motile life cycle forms achieve motility, called gliding, via the activity of an internal actomyosin motor. Although gliding is based on the well-studied system of actin and myosin, its core biomechanics are not completely understood. Currently accepted models suggest it results from a specifically organized cellular motor that produces a rearward directional force. When linked to surface-bound adhesins, this force is passaged to the cell posterior, propelling the parasite forwards. Gliding motility is observed in all three life cycle stages of Plasmodium: sporozoites, merozoites and ookinetes. However, it is only the ookinetes--formed inside the midgut of infected mosquitoes--that display continuous gliding without the necessity of host cell entry. This makes them ideal candidates for invasion-free biomechanical analysis. Here we apply a plate-based imaging approach to study ookinete motion in three-dimensional (3D) space to understand Plasmodium cell motility and how movement facilitates midgut colonization. Using single-cell tracking and numerical analysis of parasite motion in 3D, our analysis demonstrates that ookinetes move with a conserved left-handed helical trajectory. Investigation of cell morphology suggests this trajectory may be based on the ookinete subpellicular cytoskeleton, with complementary whole and subcellular electron microscopy showing that, like their motion paths, ookinetes share a conserved left-handed corkscrew shape and underlying twisted microtubular architecture. Through comparisons of 3D movement between wild-type ookinetes and a cytoskeleton-knockout mutant we demonstrate that perturbation of cell shape changes motion from helical to broadly linear. Therefore, while the precise linkages between cellular architecture and actomyosin motor organization remain unknown, our analysis suggests that the molecular basis of cell shape may, in addition to motor force, be a key adaptive strategy for malaria parasite dissemination and, as such, transmission.
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Affiliation(s)
- Andrey Kan
- Victoria Research Laboratory, National ICT Australia (NICTA), Department of Computing and Information Systems, University of Melbourne, Melbourne, Vic., 3010, Australia
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44
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The unusual dynamics of parasite actin result from isodesmic polymerization. Nat Commun 2014; 4:2285. [PMID: 23921463 PMCID: PMC3765016 DOI: 10.1038/ncomms3285] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 07/10/2013] [Indexed: 11/09/2022] Open
Abstract
Previous reports have indicated that parasite actins are short and inherently unstable, despite being required for motility. Here we re-examine the polymerization properties of actin in Toxoplasma gondii, unexpectedly finding that it exhibits isodesmic polymerization in contrast to the conventional nucleation-elongation process of all previously studied actins from both eukaryotes and bacteria. Polymerization kinetics of actin in T. gondii lacks both a lag phase and critical concentration, normally characteristic of actins. Unique among actins, the kinetics of assembly can be fit with a single set of rate constants for all subunit interactions, without need for separate nucleation and elongation rates. This isodesmic model accurately predicts the assembly, disassembly and the size distribution of actin filaments in T. gondii in vitro, providing a mechanistic explanation for actin dynamics in vivo. Our findings expand the repertoire of mechanisms by which actin polymerization is governed and offer clues about the evolution of self-assembling, stabilized protein polymers.
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45
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McGovern KE, Wilson EH. Dark side illuminated: imaging of Toxoplasma gondii through the decades. Parasit Vectors 2013; 6:334. [PMID: 24267350 PMCID: PMC4176259 DOI: 10.1186/1756-3305-6-334] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2013] [Accepted: 11/15/2013] [Indexed: 11/29/2022] Open
Abstract
In the more than 100 years since its discovery, our knowledge of Toxoplasma biology has improved enormously. The evolution of molecular biology, immunology and genomics has had profound influences on our understanding of this ubiquitous bug. However, it could be argued that in science today the adage "seeing is believing" has never been truer. Images are highly influential and in the time since the first description of T. gondii, advances in microscopy and imaging technology have been and continue to be dramatic. In this review we recount the discovery of T. gondii and the contribution of imaging techniques to elucidating its life cycle, biology and the immune response of its host.
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Affiliation(s)
- Kathryn E McGovern
- School of Medicine, Division of Biomedical Sciences, University of California, Riverside, CA 92521-0129, USA.
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46
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Ma C, Diraviyam K, Maier ME, Sept D, Sibley LD. Synthetic chondramide A analogues stabilize filamentous actin and block invasion by Toxoplasma gondii. JOURNAL OF NATURAL PRODUCTS 2013; 76:1565-1572. [PMID: 24020843 PMCID: PMC3787807 DOI: 10.1021/np400196w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Indexed: 05/31/2023]
Abstract
Apicomplexan parasites such as Toxoplasma gondii rely on actin-based motility to cross biological barriers and invade host cells. Key structural and biochemical differences in host and parasite actins make this an attractive target for small-molecule inhibitors. Here we took advantage of recent advances in the synthesis of cyclic depsipeptide compounds that stabilize filamentous actin to test the ability of chondramides to disrupt growth of T. gondii in vitro. Structural modeling of chondramide A (2) binding to an actin filament model revealed variations in the binding site between host and parasite actins. A series of 10 previously synthesized analogues (2b-k) with substitutions in the β-tyrosine moiety blocked parasite growth on host cell monolayers with EC₅₀ values that ranged from 0.3 to 1.3 μM. In vitro polymerization assays using highly purified recombinant actin from T. gondii verified that synthetic and natural product chondramides target the actin cytoskeleton. Consistent with this, chondramide treatment blocked parasite invasion into host cells and was more rapidly effective than pyrimethamine, a standard therapeutic agent. Although the current compounds lack specificity for parasite vs host actin, these studies provide a platform for the future design and synthesis of synthetic cyclic peptide inhibitors that selectively disrupt actin dynamics in parasites.
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Affiliation(s)
- Christopher
I. Ma
- Department
of Molecular Microbiology, Washington University
School of Medicine, St. Louis, Missouri 63110, United States
| | - Karthikeyan Diraviyam
- Department
of Biomedical Engineering and Center for Computational Medicine and
Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Martin E. Maier
- Institut
für Organische Chemie, Universität
Tübingen, 72076 Tübingen, Germany
| | - David Sept
- Department
of Biomedical Engineering and Center for Computational Medicine and
Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - L. David Sibley
- Department
of Molecular Microbiology, Washington University
School of Medicine, St. Louis, Missouri 63110, United States
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Valigurová A, Vaškovicová N, Musilová N, Schrével J. The enigma of eugregarine epicytic folds: where gliding motility originates? Front Zool 2013; 10:57. [PMID: 24053424 PMCID: PMC3849649 DOI: 10.1186/1742-9994-10-57] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Accepted: 08/24/2013] [Indexed: 11/12/2022] Open
Abstract
Background In the past decades, many studies focused on the cell motility of apicomplexan invasive stages as they represent a potential target for chemotherapeutic intervention. Gregarines (Conoidasida, Gregarinasina) are a heterogeneous group that parasitize invertebrates and urochordates, and are thought to be an early branching lineage of Apicomplexa. As characteristic of apicomplexan zoites, gregarines are covered by a complicated pellicle, consisting of the plasma membrane and the closely apposed inner membrane complex, which is associated with a number of cytoskeletal elements. The cell cortex of eugregarines, the epicyte, is more complicated than that of other apicomplexans, as it forms various superficial structures. Results The epicyte of the eugregarines, Gregarina cuneata, G. polymorpha and G. steini, analysed in the present study is organised in longitudinal folds covering the entire cell. In mature trophozoites and gamonts, each epicytic fold exhibits similar ectoplasmic structures and is built up from the plasma membrane, inner membrane complex, 12-nm filaments, rippled dense structures and basal lamina. In addition, rib-like myonemes and an ectoplasmic network are frequently observed. Under experimental conditions, eugregarines showed varied speeds and paths of simple linear gliding. In all three species, actin and myosin were associated with the pellicle, and this actomyosin complex appeared to be restricted to the lateral parts of the epicytic folds. Treatment of living gamonts with jasplakinolide and cytochalasin D confirmed that actin actively participates in gregarine gliding. Contributions to gliding of specific subcellular components are discussed. Conclusions Cell motility in gregarines and other apicomplexans share features in common, i.e. a three-layered pellicle, an actomyosin complex, and the polymerisation of actin during gliding. Although the general architecture and supramolecular organisation of the pellicle is not correlated with gliding rates of eugregarines, an increase in cytoplasmic mucus concentration is correlated. Furthermore, our data suggest that gregarines utilize several mechanisms of cell motility and that this is influenced by environmental conditions.
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Affiliation(s)
- Andrea Valigurová
- Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic.
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48
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Hellmann JK, Perschmann N, Spatz JP, Frischknecht F. Tunable substrates unveil chemical complementation of a genetic cell migration defect. Adv Healthc Mater 2013; 2:1162-9. [PMID: 23355513 DOI: 10.1002/adhm.201200426] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Indexed: 12/21/2022]
Abstract
Cell migration is dependent on a number of physical and chemical parameters of the substrate that influence cellular signaling events as cell surface receptors interact with the substrate. These events can strengthen or loosen the contact of the cell with its environment and need to be orchestrated for efficient motility. A set of tunable substrates was used in combination with quantitative imaging to probe for potentially subtle differences in genetically modified and chemically treated rapidly migrating cells. As model cell, Plasmodium sporozoites were used, the forms of malaria parasites transmitted by the mosquito to the host. Sporozoites lacking a substrate-binding surface protein moved on different surfaces with consistently lower efficiency and were more sensitive to adhesion ligand spacing than wild type sporozoites. Addition of an actin filament stabilizing chemical agent temporarily increased sporozoite motility on soft but not on hard substrates. Defined conditions were found where the chemical completely compensates the reduced migration capacity of the genetically modified parasites. As the onset of motility was delayed for sporozoites on unfavourable gels it is suggested that the parasite can slowly adjust to environmental elasticity, possibly by adapting the interplay between surface adhesins and actin filament dynamics. This demonstrates the utility of tunable substrates to dissect molecular function in cell adhesion and motility.
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Affiliation(s)
- Janina Kristin Hellmann
- Parasitology, Department of Infectious Diseases, University of Heidelberg Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
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Novel thioredoxin-like proteins are components of a protein complex coating the cortical microtubules of Toxoplasma gondii. EUKARYOTIC CELL 2013; 12:1588-99. [PMID: 23873863 DOI: 10.1128/ec.00082-13] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Microtubules are versatile biopolymers that support numerous vital cellular functions in eukaryotes. The specific properties of microtubules are dependent on distinct microtubule-associated proteins, as the tubulin subunits and microtubule structure are exceptionally conserved. Highly specialized microtubule-containing assemblies are often found in protists, which are rich sources for novel microtubule-associated proteins. A protozoan parasite, Toxoplasma gondii, possesses several distinct tubulin-containing structures, including 22 microtubules closely associated with the cortical membrane. Early ultrastructural studies have shown that the cortical microtubules are heavily decorated with associating proteins. However, little is known about the identities of these proteins. Here, we report the discovery of a novel protein, TrxL1 (for Thioredoxin-Like protein 1), and an associating complex that coats the cortical microtubules. TrxL1 contains a thioredoxin-like fold. To visualize its localization in live parasites by fluorescence, we replaced the endogenous TrxL1 gene with an mEmeraldFP-TrxL1 fusion gene. Structured illumination-based superresolution imaging of this parasite line produced a detailed view of the microtubule cytoskeleton. Despite its stable association with the cortical microtubules in the parasite, TrxL1 does not seem to bind to microtubules directly. Coimmunoprecipitation experiments showed that TrxL1 associates with a protein complex containing SPM1, a previously reported microtubule-associated protein in T. gondii. We also found that SPM1 recruits TrxL1 to the cortical microtubules. Besides SPM1, several other novel proteins are found in the TrxL1-containing complex, including TrxL2, a close homolog of TrxL1. Thus, our results reveal for the first time a microtubule-associated complex in T. gondii.
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Donor CD8+ T cells prevent Toxoplasma gondii de-encystation but fail to rescue the exhausted endogenous CD8+ T cell population. Infect Immun 2013; 81:3414-25. [PMID: 23817617 DOI: 10.1128/iai.00784-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Functional exhaustion of CD8(+) T cells due to increased expression of inhibitory molecule PD-1 (Programmed Death-1) causes reactivation of latent disease during later phases of chronic toxoplasmosis. Onset of disease recrudescence results in decreased parasite cyst burden concomitant with parasites undergoing stage conversion from a primarily encysted, quiescent bradyzoite to a fast-replicating, highly motile tachyzoite. Thus, reduced cyst burden is one of the early hallmarks of disease recrudescence. This was further validated by depleting gamma interferon (IFN-γ), a cytokine known to control latent toxoplasmosis, in chronically infected prerecrudescent mice. Since CD8(+) T cells (an important source of IFN-γ) lose their functionality during the later phases of chronic toxoplasmosis, we next examined if adoptive transfer of functional CD8(+) T cells from acutely infected donors to the chronically infected prerecrudescent hosts could impede parasite de-encystation and rescue exhausted CD8(+) T cells. While the transfer of immune CD8(+) T cells temporarily restricted the breakdown of cysts, the exhausted endogenous CD8(+) T cell population was not rescued. Over time, the donor population got deleted, resulting in parasite de-encystation and host mortality. Considering that donor CD8(+) T cells fail to become long-lived, one of the cardinal features of memory CD8(+) T cells, it bears the implication that memory CD8 differentiation is impaired during chronic toxoplasmosis. Moreover, our data strongly suggest that while adoptive immunotherapy can prevent parasite de-encystation transiently, reduced antigen burden in the chronic phase by itself is insufficient for rescue of exhausted CD8(+) T cells. The conclusions of this study have profound ramifications in designing immunotherapeutics against chronic toxoplasmosis.
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