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Kaffashi K, Dréau D, Nesmelova IV. Heterodimers Are an Integral Component of Chemokine Signaling Repertoire. Int J Mol Sci 2023; 24:11639. [PMID: 37511398 PMCID: PMC10380872 DOI: 10.3390/ijms241411639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 07/10/2023] [Accepted: 07/11/2023] [Indexed: 07/30/2023] Open
Abstract
Chemokines are a family of signaling proteins that play a crucial role in cell-cell communication, cell migration, and cell trafficking, particularly leukocytes, under both normal and pathological conditions. The oligomerization state of chemokines influences their biological activity. The heterooligomerization occurs when multiple chemokines spatially and temporally co-localize, and it can significantly affect cellular responses. Recently, obligate heterodimers have emerged as tools to investigate the activities and molecular mechanisms of chemokine heterodimers, providing valuable insights into their functional roles. This review focuses on the latest progress in understanding the roles of chemokine heterodimers and their contribution to the functioning of the chemokine network.
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Affiliation(s)
- Kimia Kaffashi
- Department of Biological Sciences, University of North Carolina, Charlotte, NC 28223, USA
- Department of Physics and Optical Sciences, University of North Carolina, Charlotte, NC 28223, USA
| | - Didier Dréau
- Department of Biological Sciences, University of North Carolina, Charlotte, NC 28223, USA
| | - Irina V Nesmelova
- Department of Physics and Optical Sciences, University of North Carolina, Charlotte, NC 28223, USA
- School of Data Science, University of North Carolina, Charlotte, NC 28223, USA
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2
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Joseph PRB, Spyracopoulos L, Rajarathnam K. Dynamics-Derived Insights into Complex Formation between the CXCL8 Monomer and CXCR1 N-Terminal Domain: An NMR Study. Molecules 2018; 23:E2825. [PMID: 30384436 PMCID: PMC6278376 DOI: 10.3390/molecules23112825] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 10/19/2018] [Accepted: 10/25/2018] [Indexed: 11/29/2022] Open
Abstract
Interleukin-8 (CXCL8), a potent neutrophil-activating chemokine, exerts its function by activating the CXCR1 receptor that belongs to class A G protein-coupled receptors (GPCRs). Receptor activation involves interactions between the CXCL8 N-terminal loop and CXCR1 N-terminal domain (N-domain) residues (Site-I) and between the CXCL8 N-terminal and CXCR1 extracellular/transmembrane residues (Site-II). CXCL8 exists in equilibrium between monomers and dimers, and it is known that the monomer binds CXCR1 with much higher affinity and that Site-I interactions are largely responsible for the differences in monomer vs. dimer affinity. Here, using backbone 15N-relaxation nuclear magnetic resonance (NMR) data, we characterized the dynamic properties of the CXCL8 monomer and the CXCR1 N-domain in the free and bound states. The main chain of CXCL8 appears largely rigid on the picosecond time scale as evident from high order parameters (S²). However, on average, S² are higher in the bound state. Interestingly, several residues show millisecond-microsecond (ms-μs) dynamics only in the bound state. The CXCR1 N-domain is unstructured in the free state but structured with significant dynamics in the bound state. Isothermal titration calorimetry (ITC) data indicate that both enthalpic and entropic factors contribute to affinity, suggesting that increased slow dynamics in the bound state contribute to affinity. In sum, our data indicate a critical and complex role for dynamics in driving CXCL8 monomer-CXCR1 Site-I interactions.
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Affiliation(s)
- Prem Raj B Joseph
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555, USA.
- Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Leo Spyracopoulos
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G 2H7, Canada.
| | - Krishna Rajarathnam
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX 77555, USA.
- Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX 77555, USA.
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3
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Mao Y, Meng Q, Song P, Zhu S, Xu Y, Snyder EY, An J, Huang Z. Novel Bivalent and D-Peptide Ligands of CXCR4 Mobilize Hematopoietic Progenitor Cells to the Blood in C3H/HeJ Mice. Cell Transplant 2018; 27:1249-1255. [PMID: 29991278 PMCID: PMC6434473 DOI: 10.1177/0963689718784957] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The interaction of SDF-1α (also known as CXCL12) with the CXCR4 receptor plays a critical role in the retention of hematopoietic stem cells (HSCs) in bone marrow. The viral macrophage inflammatory protein-II (vMIP-II), a human herpesvirus-8 (HHV-8)-encoded viral chemokine, can bind the CXCR4 receptor and inhibit endogenous ligand-induced calcium responses and cell migration. Previously, we used the bivalent ligand approach to link synthetically two unnatural D-amino acid peptides derived from the N-terminus of vMIP-II (DV1 and DV3, respectively) to generate a dimeric peptide, DV1-K-(DV3) (also named HC4319), which shows very high affinity for CXCR4. Here, we studied the biological effects of this dimeric peptide, HC4319, and its monomeric counterpart, DV1, on SDF-1α-induced signaling in CXCR4- or CXCR7-transfected Chinese hamster ovary cells and mobilization of hematopoietic progenitor cells (HPCs) in C3H/HeJ mice using an HPC assay. HC4319 and DV1 inhibited significantly the phosphorylation of Akt and Erk, known to be downstream signaling events of CXCR4. This in vivo study in C3H/HeJ mice showed that HC4319 and DV-1 strongly induced rapid mobilization of granulocyte-macrophage colony-forming units (CFUs), erythrocyte burst-forming units, and granulocyte-erythrocyte-monocyte-megakaryocyte CFUs from the bone marrow to the blood. These results provide the first reported experimental evidence that bivalent and D-amino acid peptides derived from the N-terminus of vMIP-II are potent mobilizers of HPCs in C3H/HeJ mice and support the further development of such agents for clinical application.
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Affiliation(s)
- Yujia Mao
- 1 School of Life Sciences, Tsinghua University, Beijing, China
| | - Qian Meng
- 1 School of Life Sciences, Tsinghua University, Beijing, China
| | - Panpan Song
- 1 School of Life Sciences, Tsinghua University, Beijing, China
| | - Siyu Zhu
- 1 School of Life Sciences, Tsinghua University, Beijing, China
| | - Yan Xu
- 1 School of Life Sciences, Tsinghua University, Beijing, China.,2 Nobel Institute of Biomedicine, Zhuhai, Guangdong, China
| | - Evan Y Snyder
- 3 Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Jing An
- 2 Nobel Institute of Biomedicine, Zhuhai, Guangdong, China.,4 Division of Infectious Diseases, Department of Medicine, School of Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Ziwei Huang
- 1 School of Life Sciences, Tsinghua University, Beijing, China.,4 Division of Infectious Diseases, Department of Medicine, School of Medicine, University of California at San Diego, La Jolla, CA, USA
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4
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Brown AJ, Joseph PRB, Sawant KV, Rajarathnam K. Chemokine CXCL7 Heterodimers: Structural Insights, CXCR2 Receptor Function, and Glycosaminoglycan Interactions. Int J Mol Sci 2017; 18:ijms18040748. [PMID: 28368308 PMCID: PMC5412333 DOI: 10.3390/ijms18040748] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 03/27/2017] [Accepted: 03/29/2017] [Indexed: 11/16/2022] Open
Abstract
Chemokines mediate diverse fundamental biological processes, including combating infection. Multiple chemokines are expressed at the site of infection; thus chemokine synergy by heterodimer formation may play a role in determining function. Chemokine function involves interactions with G-protein-coupled receptors and sulfated glycosaminoglycans (GAG). However, very little is known regarding heterodimer structural features and receptor and GAG interactions. Solution nuclear magnetic resonance (NMR) and molecular dynamics characterization of platelet-derived chemokine CXCL7 heterodimerization with chemokines CXCL1, CXCL4, and CXCL8 indicated that packing interactions promote CXCL7-CXCL1 and CXCL7-CXCL4 heterodimers, and electrostatic repulsive interactions disfavor the CXCL7-CXCL8 heterodimer. As characterizing the native heterodimer is challenging due to interference from monomers and homodimers, we engineered a “trapped” disulfide-linked CXCL7-CXCL1 heterodimer. NMR and modeling studies indicated that GAG heparin binding to the heterodimer is distinctly different from the CXCL7 monomer and that the GAG-bound heterodimer is unlikely to bind the receptor. Interestingly, the trapped heterodimer was highly active in a Ca2+ release assay. These data collectively suggest that GAG interactions play a prominent role in determining heterodimer function in vivo. Further, this study provides proof-of-concept that the disulfide trapping strategy can serve as a valuable tool for characterizing the structural and functional features of a chemokine heterodimer.
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Affiliation(s)
- Aaron J Brown
- Department of Biochemistry and Molecular Biology, and Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Prem Raj B Joseph
- Department of Biochemistry and Molecular Biology, and Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Kirti V Sawant
- Department of Biochemistry and Molecular Biology, and Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX 77555, USA.
| | - Krishna Rajarathnam
- Department of Biochemistry and Molecular Biology, and Sealy Center for Structural Biology and Molecular Biophysics, The University of Texas Medical Branch, Galveston, TX 77555, USA.
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5
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Szpakowska M, Chevigné A. vCCL2/vMIP-II, the viral master KEYmokine. J Leukoc Biol 2015; 99:893-900. [DOI: 10.1189/jlb.2mr0815-383r] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 11/20/2015] [Indexed: 11/24/2022] Open
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6
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Herring CA, Singer CM, Ermakova EA, Khairutdinov BI, Zuev YF, Jacobs DJ, Nesmelova IV. Dynamics and thermodynamic properties of CXCL7 chemokine. Proteins 2015; 83:1987-2007. [PMID: 26297927 DOI: 10.1002/prot.24913] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Revised: 08/05/2015] [Accepted: 08/18/2015] [Indexed: 11/09/2022]
Abstract
Chemokines form a family of signaling proteins mainly responsible for directing the traffic of leukocytes, where their biological activity can be modulated by their oligomerization state. We characterize the dynamics and thermodynamic stability of monomer and homodimer structures of CXCL7, one of the most abundant platelet chemokines, using experimental methods that include circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopy, and computational methods that include the anisotropic network model (ANM), molecular dynamics (MD) simulations and the distance constraint model (DCM). A consistent picture emerges for the effects of dimerization and Cys5-Cys31 and Cys7-Cys47 disulfide bonds formation. The presence of disulfide bonds is not critical for maintaining structural stability in the monomer or dimer, but the monomer is destabilized more than the dimer upon removal of disulfide bonds. Disulfide bonds play a key role in shaping the characteristics of native state dynamics. The combined analysis shows that upon dimerization flexibly correlated motions are induced between the 30s and 50s loop within each monomer and across the dimer interface. Interestingly, the greatest gain in flexibility upon dimerization occurs when both disulfide bonds are present, and the homodimer is least stable relative to its two monomers. These results suggest that the highly conserved disulfide bonds in chemokines facilitate a structural mechanism that is tuned to optimally distinguish functional characteristics between monomer and dimer.
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Affiliation(s)
- Charles A Herring
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, 28223
| | - Christopher M Singer
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, 28223
| | - Elena A Ermakova
- Kazan Institute of Biochemistry and Biophysics, Kazan, 40111, Russia
| | | | - Yuriy F Zuev
- Kazan Institute of Biochemistry and Biophysics, Kazan, 40111, Russia
| | - Donald J Jacobs
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, 28223.,Center for Biomedical Engineering, University of North Carolina, Charlotte, North Carolina, 28223
| | - Irina V Nesmelova
- Department of Physics and Optical Science, University of North Carolina, Charlotte, North Carolina, 28223.,Center for Biomedical Engineering, University of North Carolina, Charlotte, North Carolina, 28223
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7
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A biologically active vMIP-II-IgG3-TfN fusion protein, secreted from methylotrophic yeast Pichia pastoris. Protein Expr Purif 2013; 87:47-54. [DOI: 10.1016/j.pep.2012.09.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 08/28/2012] [Accepted: 09/28/2012] [Indexed: 11/17/2022]
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8
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Choi WT, Kumar S, Madani N, Han X, Tian S, Dong CZ, Liu D, Duggineni S, Yuan J, Sodroski JG, Huang Z, An J. A novel synthetic bivalent ligand to probe chemokine receptor CXCR4 dimerization and inhibit HIV-1 entry. Biochemistry 2012; 51:7078-86. [PMID: 22897429 DOI: 10.1021/bi2016712] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chemokine receptor CXCR4 is one of two principal coreceptors for the entry of HIV-1 into target cells. CXCR4 is known to form homodimers. We previously demonstrated that the amino terminus of viral macrophage protein II (vMIP-II) is the major determinant for CXCR4 recognition, and that V1 peptide derived from the N-terminus of vMIP-II (1-21 residues) showed significant CXCR4 binding. Interestingly, an all-d-amino acid analogue of V1 peptide, DV1 peptide, displayed an even higher binding affinity and strong antiviral activity in inhibiting the replication of CXCR4-dependent HIV-1 strains. In this study, we synthetically linked two DV1 peptides with the formation of a disulfide bond between the two cysteine residues present in the peptide sequence to generate a dimeric molecule potentially capable of interacting with two CXCR4 receptors. DV1 dimer exhibited enhanced binding affinity and antiviral activity compared with those of DV1 monomer. Ligand binding site mapping experiments showed that DV1 dimer overlaps with HIV-1 gp120 on CXCR4 binding sites, including several transmembrane (TM) residues located close to the extracellular side and the N-terminus of CXCR4. This finding was supported by the molecular modeling of CXCR4 dimer-DV1 dimer interaction based on the crystal structure of CXCR4, which showed that DV1 dimer is capable of interacting with the CXCR4 dimeric structure by allowing the N-terminus of each DV1 monomer to reach into the binding pocket of CXCR4 monomer. The development of this bivalent ligand provides a tool for further probing the functions of CXCR4 dimerization and studying CXCR4 heterodimerization with other receptors.
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Affiliation(s)
- Won-Tak Choi
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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9
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Dong CZ, Tian S, Choi WT, Kumar S, Liu D, Xu Y, Han X, Huang Z, An J. Critical role in CXCR4 signaling and internalization of the polypeptide main chain in the amino terminus of SDF-1α probed by novel N-methylated synthetically and modularly modified chemokine analogues. Biochemistry 2012; 51:5951-7. [PMID: 22779681 DOI: 10.1021/bi3003742] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The replication of human immunodeficiency virus type 1 (HIV-1) can be profoundly inhibited by the natural ligands of two major HIV-1 coreceptors, CXCR4 and CCR5. Stromal cell-derived factor-1α (SDF-1α) is a natural ligand of CXCR4. We have recently developed a synthetic biology approach of using synthetically and modularly modified (SMM)-chemokines to dissect various aspects of the structure-function relationship of chemokines and their receptors. Here, we used this approach to design novel SMM-SDF-1α analogues containing unnatural N-methylated residues in the amino terminus to investigate whether the polypeptide main chain amide bonds in the N-terminus of SDF-1α play a role in SDF-1α signaling via CXCR4 and/or receptor internalization. The results show that SDF-1α analogues with a modified N-methylated main chain at position 2, 3, or 5 retain significant CXCR4 binding and yet completely lose signaling activities. Furthermore, a representative N-methylated analogue has been shown to be incapable of causing CXCR4 internalization. These results suggest that the ability of SDF-1α to activate CXCR4 signaling and internalization is dependent upon the main chain amide bonds in the N-terminus of SDF-1α. This study demonstrates the feasibility and value of applying a synthetic biology approach to chemically engineer natural proteins and peptide ligands as probes of important biological functions that are not addressed by other biological techniques.
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Affiliation(s)
- Chang-Zhi Dong
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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10
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Potent strategy to inhibit HIV-1 by binding both gp120 and gp41. Antimicrob Agents Chemother 2010; 55:264-75. [PMID: 20956603 DOI: 10.1128/aac.00376-10] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The development of an anti-HIV microbicide is critical in the fight against the spread of HIV. It is shown here that the covalent linking of compounds that bind gp120 with compounds that bind gp41 can inhibit HIV entry even more potently than individual inhibitors or noncovalent combinations. The most striking example involves griffithsin, a potent HIV inhibitor that binds to the surface of HIV gp120. While griffithsin inhibits HIV Env-mediated fusion in a CCR5-tropic cell-cell fusion assay with a 50% inhibitory concentration (IC(50)) of 1.31 ± 0.87 nM and the gp41-binding peptide C37 shows an IC(50) of 18.2 ± 7.6 nM, the covalently linked combination of griffithsin with C37 (Griff37) has an IC(50) of 0.15 ± 0.05 nM, exhibiting a potency 8.7-fold greater than that of griffithsin alone. Similarly, in CXCR4-tropic cell-cell fusion assays, Griff37 is 5.2-fold more potent than griffithsin alone. In viral assays, both griffithsin and Griff37 inhibit HIV replication at midpicomolar levels, but the linked compound Griff37 is severalfold more potent than griffithsin alone against both CCR5- and CXCR4-tropic virus strains. Another example of this strategy is the covalently linked combination of peptide C37 with a variant of the gp120-binding peptide CD4M33 (L. Martin et al., Nat. Biotechnol. 21:71-76, 2003). Also, nuclear magnetic resonance (NMR) spectra for several of these compounds are shown, including, to our knowledge, the first published NMR spectrum for griffithsin.
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11
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Erat MC, Schwarz-Linek U, Pickford AR, Farndale RW, Campbell ID, Vakonakis I. Implications for collagen binding from the crystallographic structure of fibronectin 6FnI1-2FnII7FnI. J Biol Chem 2010; 285:33764-70. [PMID: 20739283 PMCID: PMC2962475 DOI: 10.1074/jbc.m110.139394] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Collagen and fibronectin (FN) are two abundant and essential components of the vertebrate extracellular matrix; they interact directly with cellular receptors and affect cell adhesion and migration. Past studies identified a FN fragment comprising six modules, 6FnI1–2FnII7–9FnI, and termed the gelatin binding domain (GBD) as responsible for collagen interaction. Recently, we showed that the GBD binds tightly to a specific site within type I collagen and determined the structure of domains 8–9FnI in complex with a peptide from that site. Here, we present the crystallographic structure of domains 6FnI1–2FnII7FnI, which form a compact, globular unit through interdomain interactions. Analysis of NMR titrations with single-stranded collagen peptides reveals a dominant collagen interaction surface on domains 2FnII and 7FnI; a similar surface appears involved in interactions with triple-helical peptides. Models of the complete GBD, based on the new structure and the 8–9FnI·collagen complex show a continuous putative collagen binding surface. We explore the implications of this model using long collagen peptides and discuss our findings in the context of FN interactions with collagen fibrils.
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Affiliation(s)
- Michèle C Erat
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
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12
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Bae SH, Dyson HJ, Wright PE. Prediction of the rotational tumbling time for proteins with disordered segments. J Am Chem Soc 2009; 131:6814-21. [PMID: 19391622 DOI: 10.1021/ja809687r] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
For well-structured, rigid proteins, the prediction of rotational tumbling time (tau(c)) using atomic coordinates is reasonably accurate, but is inaccurate for proteins with long unstructured sequences. Under physiological conditions, many proteins contain long disordered segments that play important regulatory roles in fundamental biological events including signal transduction and molecular recognition. Here we describe an ensemble approach to the boundary element method that accurately predicts tau(c) for such proteins by introducing two layers of molecular surfaces whose correlated velocities decay exponentially with distance. Reliable prediction of tau(c) will help to detect intra- and intermolecular interactions and conformational switches between more ordered and less ordered states of the disordered segments. The method has been extensively validated using 12 reference proteins with 14 to 103 disordered residues at the N- and/or C-terminus and has been successfully employed to explain a set of published results on a system that incorporates a conformational switch.
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Affiliation(s)
- Sung-Hun Bae
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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13
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Control of feeding behavior in C. elegans by human G protein-coupled receptors permits screening for agonist-expressing bacteria. Proc Natl Acad Sci U S A 2008; 105:14826-31. [PMID: 18815363 DOI: 10.1073/pnas.0803290105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
G protein-coupled receptors (GPCRs) have a key role in many biological processes and are important drug targets for many human diseases. Therefore, understanding the molecular interactions between GPCRs and their ligands would improve drug design. Here, we describe an approach that allows the rapid identification of functional agonists expressed in bacteria. Transgenic Caenorhabditis elegans expressing the human chemokine receptor 5 (CCR5) in nociceptive neurons show avoidance behavior on encounter with the ligand MIP-1alpha and avoid feeding on Escherichia coli expressing MIP-1alpha compared with control bacteria. This system allows a simple activity screen, based on the distribution of transgenic worms in a binary food-choice assay, without a requirement for protein purification or tagging. By using this approach, a library of 68 MIP-1alpha variants was screened, and 13 critical agonist residues involved in CCR5 activation were identified, four of which (T8, A9, N22, and A25) have not been described previously, to our knowledge. Identified residues were subsequently validated in receptor binding assays and by calcium flux assays in mammalian cells. This approach serves not only for structure/function studies as demonstrated, but may be used to facilitate the discovery of agonists within bacterial libraries.
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14
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Nesmelova IV, Sham Y, Gao J, Mayo KH. CXC and CC chemokines form mixed heterodimers: association free energies from molecular dynamics simulations and experimental correlations. J Biol Chem 2008; 283:24155-66. [PMID: 18550532 DOI: 10.1074/jbc.m803308200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CXC and CC chemokines are involved in numerous biological processes, and their function in situ may be significantly influenced by heterodimer formation, as was recently reported, for example, for CXC chemokines CXCL4/PF4 and CXCL8/IL8 that interact to form heterodimers that modulate chemotactic and cell proliferation activities. Here we used molecular dynamics simulations to determine relative association free energies (overall average and per residue) for homo- and heterodimer pairs of CXC (CXCL4/PF4, CXCL8/IL8, CXCL1/Gro-alpha, and CXCL7/NAP-2) and CC (CCL5/RANTES, CCL2/MCP-1, and CCL8/MCP-2) chemokines. Even though structural homology among monomer folds of all CXC and CC chemokines permits heterodimer assembly, our calculated association free energies depend upon the particular pair of chemokines in terms of the net electrostatic and nonelectrostatic forces involved, as well as (for CC/CXC mixed chemokines) the selection of dimer type (CC or CXC). These relative free energies indicate that association of some pairs of chemokines is more favorable than others. Our approach is validated by correlation of calculated and experimentally determined free energies. Results are discussed in terms of CXC and CC chemokine function and have significant biological implications.
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Affiliation(s)
- Irina V Nesmelova
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 321 Church Street, Minneapolis, MN 55455, USA
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15
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Jarymowycz VA, Stone MJ. Fast time scale dynamics of protein backbones: NMR relaxation methods, applications, and functional consequences. Chem Rev 2007; 106:1624-71. [PMID: 16683748 DOI: 10.1021/cr040421p] [Citation(s) in RCA: 342] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Virginia A Jarymowycz
- Department of Chemistry and Interdisciplinary Biochemistry Program, Indiana University, Bloomington, Indiana 47405-0001, USA
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16
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Gao T, Zhang X, Ivleva NB, Golden SS, LiWang A. NMR structure of the pseudo-receiver domain of CikA. Protein Sci 2007; 16:465-75. [PMID: 17322531 PMCID: PMC2203319 DOI: 10.1110/ps.062532007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The circadian input kinase (CikA) is a major element of the pathway that provides environmental information to the circadian clock of the cyanobacterium Synechococcus elongatus. CikA is a polypeptide of 754 residues and has three recognizable domains: GAF, histidine protein kinase, and receiver-like. This latter domain of CikA lacks the conserved phospho-accepting aspartyl residue of bona fide receiver domains and is thus a pseudo-receiver (PsR). Recently, it was shown that the PsR domain (1) attenuates the autokinase activity of CikA, (2) is necessary to localize CikA to the cell pole, and (3) is necessary for the destabilization of CikA in the presence of the quinone analog 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB). The solution structure of the PsR domain of CikA, CikAPsR, is presented here. A model of the interaction between the PsR domain and HPK portion of CikA provides a potential explanation for how the PsR domain attenuates the autokinase activity of CikA. Finally, a likely quinone-binding surface on CikAPsR is shown here.
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Affiliation(s)
- Tiyu Gao
- Center for Research on Biological Clocks, Texas A&M University College Station, Texas 77843, USA
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17
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Vakonakis I, Klewer DA, Williams SB, Golden SS, LiWang AC. Structure of the N-terminal Domain of the Circadian Clock-associated Histidine Kinase SasA. J Mol Biol 2004; 342:9-17. [PMID: 15313603 DOI: 10.1016/j.jmb.2004.07.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2004] [Revised: 07/08/2004] [Accepted: 07/09/2004] [Indexed: 11/20/2022]
Abstract
Circadian oscillators are endogenous biological systems that generate the approximately 24 hour temporal pattern of biological processes and confer a reproductive fitness advantage to their hosts. The cyanobacterial clock is the simplest known and the only clock system for which structural information for core component proteins, in this case KaiA, KaiB and KaiC, is available. SasA, a clock-associated histidine kinase, is necessary for robustness of the circadian rhythm of gene expression and implicated in clock output. The N-terminal domain of SasA (N-SasA) interacts directly with KaiC and likely functions as the sensory domain controlling the SasA histidine kinase activity. N-SasA and KaiB share significant sequence similarity and, thus, it has been proposed that they would be structurally similar and may even compete for KaiC binding. Here, we report the NMR structure of N-SasA and show it to be different from that of KaiB. The structural comparisons provide no clear details to suggest competition of SasA and KaiB for KaiC binding. N-SasA adopts a canonical thioredoxin fold but lacks the catalytic cysteine residues. A patch of conserved, solvent-exposed residues is found near the canonical thioredoxin active site. We suggest that this surface is used by N-SasA for protein-protein interactions. Our analysis suggests that the structural differences between N-SasA and KaiB are the result of only a few critical amino acid substitutions.
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Affiliation(s)
- Ioannis Vakonakis
- Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843, USA
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18
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Vakonakis I, LiWang AC. Structure of the C-terminal domain of the clock protein KaiA in complex with a KaiC-derived peptide: implications for KaiC regulation. Proc Natl Acad Sci U S A 2004; 101:10925-30. [PMID: 15256595 PMCID: PMC503721 DOI: 10.1073/pnas.0403037101] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Circadian clocks are widespread endogenous mechanisms that control the temporal pattern of diverse biological processes, including gene transcription. KaiA is the positive element of the cyanobacterial clock because KaiA overexpression elevates transcription levels of clock components. Recently, we showed that the structure of KaiA is that of a domain-swapped homodimer. The N-terminal domain is a pseudo-receiver; thus, it is likely to be involved in signal transduction in the clock-resetting pathway. The C-terminal domain of KaiA is structurally novel and enhances the KaiC autokinase activity directly. Here, we report the NMR structure of the C-terminal domain of KaiA (ThKaiA180C) in complex with a KaiC-derived peptide from the cyanobacterium Thermosynechococcus elongatus BP-1. The protein-peptide interface is revealed to be different from a model that was proposed earlier, is stabilized by a combination of hydrophobic and electrostatic interactions, and includes many residues known to produce a circadian-period phenotype upon substitution. Although the structure of the monomeric subunit of ThKaiA180C is largely unchanged upon peptide binding, the intersubunit dimerization angle changes. It is proposed that modulation of the C-terminal KaiA domain dimerization angle regulates KaiA-KaiC interactions.
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Affiliation(s)
- Ioannis Vakonakis
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, 77843-2128, USA
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19
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Vakonakis I, Sun J, Wu T, Holzenburg A, Golden SS, LiWang AC. NMR structure of the KaiC-interacting C-terminal domain of KaiA, a circadian clock protein: implications for KaiA-KaiC interaction. Proc Natl Acad Sci U S A 2004; 101:1479-84. [PMID: 14749515 PMCID: PMC341745 DOI: 10.1073/pnas.0305516101] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2003] [Accepted: 12/05/2003] [Indexed: 11/18/2022] Open
Abstract
KaiA is a two-domain circadian clock protein in cyanobacteria, acting as the positive element in a feedback loop that sustains the oscillation. The structure of the N-terminal domain of KaiA is that of a pseudo-receiver, similar to those of bacterial response regulators, which likely interacts with components of the clock-resetting pathway. The C-terminal domain of KaiA is highly conserved among cyanobacteria and enhances the autokinase activity of KaiC. Here we present the NMR structure of the C-terminal domain of KaiA from the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1. This domain adopts a novel all alpha-helical homodimeric structure. Several mutations known to affect the period of the circadian oscillator are shown to be located at an exposed groove near the dimer interface. This NMR structure and a 21-A-resolution electron microscopy structure of the hexameric KaiC particle allow us to postulate a mode of KaiA-KaiC interaction, in which KaiA binds a linker region connecting two globular KaiC domains.
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Affiliation(s)
- Ioannis Vakonakis
- Departments of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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20
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Morris KV, Higgins J, Shen X, Stine JT, Pedersen NC. The effects of HHV-8 vMIP-II on SIVmac251 infection and replication competent and incompetent SIVmac239Delta3 vectors. Virus Res 2003; 94:103-12. [PMID: 12902039 DOI: 10.1016/s0168-1702(03)00138-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Human herpesvirus type 8 vMIP-II has one of the broadest ranges of chemokine receptor binding and therefore a multiplicity of biologic effects, both immunologic and antiviral. These properties make vMIP-II an attractive effector gene to be expressed from gene therapy vectors. The present studies were concerned with both therapeutic approaches: (1) an anti-simian immunodeficiency virus (SIV) biologic, and (2) an effector gene in SIV-based vectors. Regarding its antiviral properties, vMIP-II expressed from bacteria and SIV-based vectors bound the surface of CEMx174 cells and specifically suppressed SIVmac251 infection. A CCR3 monoclonal antibody partially inhibited vMIP-II binding, suggesting that both SIVmac251 and vMIP-II utilize a similar CCR3-like receptor for CEMx174 cell binding. Replication competent SIV-based vectors containing forward and reverse vMIP-II produced neither identifiable vMIP-II nor virions for the first 21 days. Virus replication occurred after this period. Significant sequence alterations in the forward vMIP-II containing replication competent vector transcripts were responsible for the failure of vMIP-II expression. The genetic basis for the initial failure to replicate virus and its later restoration was not determined but appeared in the II-PIMv containing vectors to coincide with deletions and compensatory rearrangements in nef 3' of the polypurine tract. Cells transfected with SIVmac239Delta3DeltaLTR-vMIP-II vectors expressed biologically active vMIP-II that bound CEMx174 cells and suppressed SIVmac251 infection. These data suggest that replication defective SIV vectors expressing immunobiolgic genes such as vMIP-II may prove useful in gene therapies, particularly in augmenting immune responses in chronically infected individuals.
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Affiliation(s)
- Kevin V Morris
- Department of Medicine 0678, Stein Clinical Research Building, Room 402, University of California, La Jolla, San Diego, CA 92093-0678, USA.
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21
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Schuman J, Campbell AP, Koganty RR, Longenecker BM. Probing the conformational and dynamical effects of O-glycosylation within the immunodominant region of a MUC1 peptide tumor antigen. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2003; 61:91-108. [PMID: 12558945 DOI: 10.1034/j.1399-3011.2003.00031.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
MUC1 mucin is a large transmembrane glycoprotein, the extracellular domain of which is formed by a repeating 20 amino acid sequence, GVTSAPDTRPAPGSTAPPAH. In normal breast epithelial cells, the extracellular domain is densely covered with highly branched complex carbohydrate structures. However, in neoplastic breast tissue, the extracellular domain is under-glycosylated, resulting in the exposure of a highly immunogenic core peptide epitope (PDTRP in bold above), as well as in the exposure of normally cryptic core Tn (GalNAc), STn (sialyl alpha2-6 GalNAc) and TF (Gal beta1-3 GalNAc) carbohydrates. Here, we report the results of 1H NMR structural studies, natural abundance 13C NMR relaxation measurements and distance-restrained MD simulations designed to probe the structural and dynamical effects of Tn-glycosylation within the PDTRP core peptide epitope. Two synthetic peptides were studied: a nine-residue MUC1 peptide of the sequence, Thr1-Ser2-Ala3-Pro4-Asp5-Thr6-Arg7-Pro8-Ala9, and a Tn-glycosylated version of this peptide, Thr1-Ser2-Ala3-Pro4-Asp5-Thr6(alphaGalNAc)-Arg7-Pro8-Ala9. The results of these studies show that a type I beta-turn conformation is adopted by residues PDTR within the PDTRP region of the unglycosylated MUC1 sequence. The existence of a similar beta-turn within the PDTRP core peptide epitope of the under-glycosylated cancer-associated MUC1 mucin protein might explain the immunodominance of this region in vivo, as the presence of defined secondary structure within peptide epitope regions has been correlated with increased immunogenicity in other systems. Our results have also shown that Tn glycosylation at the central threonine within the PDTRP core epitope region shifts the conformational equilibrium away from the type I beta-turn conformation and toward a more rigid and extended state. The significance of these results are discussed in relation to the possible roles that peptide epitope secondary structure and glycosylation state may play in MUC1 tumor immunogenicity.
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Affiliation(s)
- J Schuman
- Department of Medicinal Chemistry, School of Pharmacy, University of Washington, Seattle 98195, USA.
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22
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Mayer KL, Stone MJ. Backbone dynamics of the CC-chemokine eotaxin-2 and comparison among the eotaxin group chemokines. Proteins 2003; 50:184-91. [PMID: 12486712 DOI: 10.1002/prot.10238] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The eotaxin group chemokines (eotaxin, eotaxin-2, and eotaxin-3) share only 35-41% sequence identity but are all agonists for the receptor CCR3. Here we present a detailed comparison between the backbone dynamics of these three chemokines. The dynamics of eotaxin-2 were determined from 15N NMR relaxation data and compared to those obtained previously for eotaxin and eotaxin-3. For all three chemokines, the majority of residues in the first two beta-strands and the alpha-helix show highly restricted motions on the subnanosecond time scale but there is dramatically higher flexibility in the N- and C-terminal regions and also substantial mobility for residues in the N-loop region and the third beta-strand. The latter two regions form a groove on the chemokine surface that is the likely binding site for the N-terminal region of the receptor. Taken together, the available data suggest a model in which conformational rearrangements of both the chemokine and the receptor are likely to occur during binding and receptor activation.
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Affiliation(s)
- Kristen L Mayer
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-0001, USA
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23
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Williams SB, Vakonakis I, Golden SS, LiWang AC. Structure and function from the circadian clock protein KaiA of Synechococcus elongatus: a potential clock input mechanism. Proc Natl Acad Sci U S A 2002; 99:15357-62. [PMID: 12438647 PMCID: PMC137721 DOI: 10.1073/pnas.232517099] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2002] [Indexed: 11/18/2022] Open
Abstract
In the cyanobacterium Synechococcus elongatus (PCC 7942) the proteins KaiA, KaiB, and KaiC are required for circadian clock function. We deduced a circadian clock function for KaiA from a combination of biochemical and structural data. Both KaiA and its isolated carboxyl-terminal domain (KaiA180C) stimulated KaiC autophosphorylation and facilitated attenuation of KaiC autophosphorylation by KaiB. An amino-terminal domain (KaiA135N) had no function in the autophosphorylation assay. NMR structure determination showed that KaiA135N is a pseudo-receiver domain. We propose that this pseudo-receiver is a timing input-device that regulates KaiA stimulation of KaiC autophosphorylation, which in turn is essential for circadian timekeeping.
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Affiliation(s)
- Stanly B Williams
- Department of Biology, Texas A&M University, College Station 77843, USA
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24
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Abstract
Chemokines are the largest family of cytokines in human immunophysiology. These proteins are defined by four invariant cysteines and are categorized based on the sequence around the first two cysteines, which leads to two major and two minor subfamilies. Chemokines function by activating specific G protein-coupled receptors, which results in, among other functions, the migration of inflammatory and noninflammatory cells to the appropriate tissues or compartments within tissues. Some of these proteins and receptors have been implicated or shown to be involved in inflammation, autoimmune diseases, and infection by HIV-1. The three-dimensional structure of each monomer is virtually identical, but the quaternary structure of chemokines is different for each subfamily. Structure-function studies reveal several regions of chemokines to be involved in function, with the N-terminal region playing a dominant role. A number of proteins and small-molecule antagonists have been identified that inhibit chemokine activities. In this review, we discuss aspects of the structure, function, and inhibition of chemokines.
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Affiliation(s)
- Elias J Fernandez
- Department of Pharmacology, Yale University, New Haven, Connecticut 06520-8066, USA.
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25
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Shao W, Fernandez E, Sachpatzidis A, Wilken J, Thompson DA, Schweitzer BI, Lolis E. CCR2 and CCR5 receptor-binding properties of herpesvirus-8 vMIP-II based on sequence analysis and its solution structure. ACTA ACUST UNITED AC 2001; 268:2948-59. [PMID: 11358512 DOI: 10.1046/j.1432-1327.2001.02184.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Human herpesvirus-8 (HHV-8) is the infectious agent responsible for Kaposi's sarcoma and encodes a protein, macrophage inflammatory protein-II (vMIP-II), which shows sequence similarity to the human CC chemokines. vMIP-II has broad receptor specificity that crosses chemokine receptor subfamilies, and inhibits HIV-1 viral entry mediated by numerous chemokine receptors. In this study, the solution structure of chemically synthesized vMIP-II was determined by nuclear magnetic resonance. The protein is a monomer and possesses the chemokine fold consisting of a flexible N-terminus, three antiparallel beta strands, and a C-terminal alpha helix. Except for the N-terminal residues (residues 1-13) and the last two C-terminal residues (residues 73-74), the structure of vMIP-II is well-defined, exhibiting average rmsd of 0.35 and 0.90 A for the backbone heavy atoms and all heavy atoms of residues 14-72, respectively. Taking into account the sequence differences between the various CC chemokines and comparing their three-dimensional structures allows us to implicate residues that influence the quaternary structure and receptor binding and activation of these proteins in solution. The analysis of the sequence and three-dimensional structure of vMIP-II indicates the presence of epitopes involved in binding two receptors CCR2 and CCR5. We propose that vMIP-II was initially specific for CCR5 and acquired receptor-binding properties to CCR2 and other chemokine receptors.
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MESH Headings
- Amino Acid Sequence
- Animals
- Binding Sites
- Chemokines/chemistry
- Chemokines/metabolism
- Chemokines, CC/chemistry
- Dimerization
- Epitopes
- Magnetic Resonance Spectroscopy
- Models, Chemical
- Models, Molecular
- Molecular Sequence Data
- Peptide Biosynthesis
- Protein Binding
- Protein Conformation
- Protein Folding
- Protein Structure, Secondary
- Receptors, CCR2
- Receptors, CCR5/chemistry
- Receptors, CCR5/metabolism
- Receptors, Chemokine/chemistry
- Receptors, Chemokine/metabolism
- Sequence Analysis, Protein
- Sequence Homology, Amino Acid
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Affiliation(s)
- W Shao
- Walt Disney Memorial Cancer Institute at Florida Hospital, Orlando, FL, USA
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26
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Seet BT, Singh R, Paavola C, Lau EK, Handel TM, McFadden G. Molecular determinants for CC-chemokine recognition by a poxvirus CC-chemokine inhibitor. Proc Natl Acad Sci U S A 2001; 98:9008-13. [PMID: 11470923 PMCID: PMC55364 DOI: 10.1073/pnas.171069398] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Poxviruses express a family of secreted proteins that bind with high affinity to chemokines and antagonize the interaction with their cognate G protein-coupled receptors (GPCRs). These viral inhibitors are novel in structure and, unlike cellular chemokine receptors, are able to specifically interact with most, if not all, CC-chemokines. We therefore sought to define the structural features of CC-chemokines that facilitate this broad-spectrum interaction. Here, we identify the residues present on human monocyte chemoattractant protein-1 (MCP-1) that are required for high-affinity interaction with the vaccinia virus 35-kDa CC-chemokine binding protein (VV-35kDa). Not only do these residues correspond to those required for interaction with the cognate receptor CCR2b but they are also conserved among many CC-chemokines. Thus, the results provide a structural basis for the ability of VV-35kDa to promiscuously recognize CC-chemokines and block binding to their receptors.
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Affiliation(s)
- B T Seet
- Viral Immunology & Pathogenesis Laboratories, John P. Robarts Research Institute, 1400 Western Road, Room 133, London, ON, Canada N6G 2V4
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27
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Abstract
Chemokines are a family of proteins involved in inflammatory and immune response. They share a common fold, made up of a three-stranded beta-sheet, and an overlaying alpha-helix. Chemokines are mainly categorized into two subfamilies distinguished by the presence or absence of a residue between two conserved cysteines in the N-terminus. Although dimers and higher-order quaternary structures are common in chemokines, they are known to function as monomers. Yet, there is quite a bit of controversy on how the actual function takes place. The mechanisms of binding and activation in the chemokine family are investigated using the gaussian network model of proteins, a low-resolution model that monitors the collective motions in proteins. It is particularly suitable for elucidating the global dynamic characteristics of large proteins or the common properties of a group of related proteins such as the chemokine family presently investigated. A sample of 16 proteins that belong to the CC, CXC, or CX(3)C subfamilies are inspected. Local packing density and packing order of residues are used to determine the type and range of motions on a global scale, such as those occurring between various loop regions. The 30s-loop, although not directly involved in the binding interface like the N-terminus and the N-loop, is identified as having a prominent role in both binding/activation and dimerization. Two mechanisms are distinguished based on the communication among the three flexible regions. In these two-step mechanisms, the 30s-loop assists either the N-loop or the N-terminus during binding and activation. The findings are verified by molecular mechanics and molecular dynamics simulations carried out on the detailed structure of representative proteins from each mechanism type. A basis for the construction of hybrids of chemokines to bind and/or activate various chemokine receptors is presented. Proteins 2001;43:150-160.
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Affiliation(s)
- C Baysal
- Faculty of Engineering and Natural Sciences, Sabanci University, Tuzla 81474, Istanbul, Turkey.
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28
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Rajarathnam K, Li Y, Rohrer T, Gentz R. Solution structure and dynamics of myeloid progenitor inhibitory factor-1 (MPIF-1), a novel monomeric CC chemokine. J Biol Chem 2001; 276:4909-16. [PMID: 11060285 DOI: 10.1074/jbc.m005085200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
MPIF-1, a CC chemokine, is a specific inhibitor of myeloid progenitor cells and is the most potent activator of monocytes. The solution structure of myeloid progenitor inhibitor factor-1 (MPIF-1) has been determined by NMR spectroscopy. The structure reveals that MPIF-1 is a monomer with a well defined core except for termini residues and adopts the chemokine fold of three beta-strands and an overlying alpha-helix. In addition to the four cysteines that characterize most chemokines, MPIF-1 has two additional cysteines that form a disulfide bond. The backbone dynamics indicate that the disulfide bonds and the adjacent residues that include the functionally important N-terminal and N-terminal loop residues show significant dynamics. MPIF-1 is a highly basic protein (pI >9), and the structure reveals distinct positively charged pockets that could be correlated to proteoglycan binding. MPIF-1 is processed from a longer proprotein at the N terminus and the latter is also functional though with reduced potency, and both proteins exist as monomers under a variety of solution conditions. MPIF-1 is therefore unique because longer proproteins of all other chemokines oligomerize in solution. The MPIF-1 structure should serve as a template for future functional studies that could lead to therapeutics for preventing chemotherapy-associated myelotoxicity.
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Affiliation(s)
- K Rajarathnam
- Department of Human Biological Chemistry and Genetics and Sealy Center for Structural Biology, University of Texas Medical Branch, Galveston, TX 77555, USA.
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29
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Lüttichau HR, Stine J, Boesen TP, Johnsen AH, Chantry D, Gerstoft J, Schwartz TW. A highly selective CC chemokine receptor (CCR)8 antagonist encoded by the poxvirus molluscum contagiosum. J Exp Med 2000; 191:171-80. [PMID: 10620615 PMCID: PMC2195798 DOI: 10.1084/jem.191.1.171] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The MC148 CC chemokine from the human poxvirus molluscum contagiosum (MCV) was probed in parallel with viral macrophage inflammatory protein (vMIP)-II encoded by human herpesvirus 8 (HHV8) in 16 classified human chemokine receptors. In competition binding using radiolabeled endogenous chemokines as well as radiolabeled MC148, MC148 bound with high affinity only to CCR8. In calcium mobilization assays, MC148 had no effect on its own on any of the chemokine receptors, but in a dose-dependent manner blocked the stimulatory effect of the endogenous I-309 chemokine on CCR8 without affecting chemokine-induced signaling of any other receptor. In contrast, vMIP-II acted as an antagonist on 10 of the 16 chemokine receptors, covering all four classes: XCR, CCR, CXCR, and CX(3)CR. In chemotaxis assays, MC148 specifically blocked the I-309-induced response but, for example, not stromal cell-derived factor 1alpha, monocyte chemoattractant protein 1, or interleukin 8-induced chemotaxis. We thus concluded that the two viruses choose two different ways to block the chemokine system: HHV8 encodes the broad-spectrum chemokine antagonist vMIP-II, whereas MCV encodes a highly selective CCR8 antagonist, MC148, conceivably to interfere with monocyte invasion and dendritic cell function. Because of its pharmacological selectivity, the MC148 protein could be a useful tool in the delineation of the role played by CCR8 and its endogenous ligand, I-309.
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Affiliation(s)
- Hans R. Lüttichau
- From the Laboratory for Molecular Pharmacology, Panum Institute, DK-2200 Copenhagen, Denmark
- Department of Infectious Diseases, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | | | - Thomas P. Boesen
- From the Laboratory for Molecular Pharmacology, Panum Institute, DK-2200 Copenhagen, Denmark
| | - Anders H. Johnsen
- Department of Clinical Biochemistry, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | | | - Jan Gerstoft
- Department of Infectious Diseases, Rigshospitalet, DK-2100 Copenhagen, Denmark
| | - Thue W. Schwartz
- From the Laboratory for Molecular Pharmacology, Panum Institute, DK-2200 Copenhagen, Denmark
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30
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Liwang AC, Wang ZX, Sun Y, Peiper SC, Liwang PJ. The solution structure of the anti-HIV chemokine vMIP-II. Protein Sci 1999; 8:2270-80. [PMID: 10595530 PMCID: PMC2144214 DOI: 10.1110/ps.8.11.2270] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
We report the solution structure of the chemotactic cytokine (chemokine) vMIP-II. This protein has unique biological activities in that it blocks infection by several different human immunodeficiency virus type 1 (HIV-1) strains. This occurs because vMIP-II binds to a wide range of chemokine receptors, some of which are used by HJV to gain cell entry. vMIP-II is a monomeric protein, unlike most members of the chemokine family, and its structure consists of a disordered N-terminus, followed by a helical turn (Gln25-Leu27), which leads into the first strand of a three-stranded antiparallel beta-sheet (Ser29-Thr34; Gly42-Thr47; Gln52-Asp56). Following the sheet is a C-terminal alpha-helix, which extends from residue Asp60 until Gln68. The final five residues beyond the C-terminal helix (Pro70-Arg74) are in an extended conformation, but several of these C-terminal residues contact the first beta-strand. The structure of vMIP-II is compared to other chemokines that also block infection by HIV-1, and the structural basis of its lack of ability to form a dimer is discussed.
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Affiliation(s)
- A C Liwang
- Texas A&M University, Department of Biochemistry and Biophysics, College Station 77843-2128, USA
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31
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Crump MP, Spyracopoulos L, Lavigne P, Kim KS, Clark-lewis I, Sykes BD. Backbone dynamics of the human CC chemokine eotaxin: fast motions, slow motions, and implications for receptor binding. Protein Sci 1999; 8:2041-54. [PMID: 10548050 PMCID: PMC2144122 DOI: 10.1110/ps.8.10.2041] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Eotaxin is a member of the chemokine family of about 40 proteins that induce cell migration. Eotaxin binds the CC chemokine receptor CCR3 that is highly expressed by eosinophils, and it is considered important in the pathology of chronic respiratory disorders such as asthma. The high resolution structure of eotaxin is known. The 74 amino acid protein has two disulfide bridges and shows a typical chemokine fold comprised of a core of three antiparallel beta-strands and an overlying alpha-helix. In this paper, we report the backbone dynamics of eotaxin determined through 15N-T1, T2, and [1H]-15N nuclear Overhauser effect heteronuclear multidimensional NMR experiments. This is the first extensive study of the dynamics of a chemokine derived from 600, 500, and 300 MHz NMR field strengths. From the T1, T2, and NOE relaxation data, parameters that describe the internal motions of eotaxin were derived using the Lipari-Szabo model free analysis. The most ordered regions of the protein correspond to the known secondary structure elements. However, surrounding the core, the regions known to be functionally important in chemokines show a range of motions on varying timescales. These include extensive subnanosecond to picosecond motions in the N-terminus, C-terminus, and the N-loop succeeding the disulfides. Analysis of rotational diffusion anisotropy of eotaxin and chemical exchange terms at multiple fields also allowed the confident identification of slow conformational exchange through the "30s" loop, disulfides, and adjacent residues. In addition, we show that these motions may be attenuated in the dimeric form of a synthetic eotaxin. The structure and dynamical basis for eotaxin receptor binding is discussed in light of the dynamics data.
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Affiliation(s)
- M P Crump
- The Protein Engineering Network of Centres of Excellence and Department of Biochemistry, University of Alberta, Edmonton, Canada
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32
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Abstract
Chemokines and chemokine receptors play a critical role in the host defense against viruses by mobilizing leukocytes to sites of infection, injury and inflammation. In order to replicate successfully within their host organisms, viruses have devised novel strategies for exploiting or subverting chemokine networks. This review summarizes various mechanisms that are currently known to be used by viruses for modulating chemokine activities including viral homologs of chemokines and chemokine receptors and soluble viral chemokine binding proteins. Insight into these strategies is providing a wealth of information on viral-host interactions, the function of chemokines in host defense and may help to generate novel anti-chemokine agents for treating against viral diseases or inflammatory disorders.
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Affiliation(s)
- A S Lalani
- Howard Hughes Medical Institute and Department of Microbiology and Immunology, University of California San Francisco, 94143-0414, USA.
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