1
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Yamaguchi H, Morikawa M, Kikkawa M. Calaxin stabilizes the docking of outer arm dyneins onto ciliary doublet microtubule in vertebrates. eLife 2023; 12:e84860. [PMID: 37057896 PMCID: PMC10139691 DOI: 10.7554/elife.84860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 04/14/2023] [Indexed: 04/15/2023] Open
Abstract
Outer arm dynein (OAD) is the main force generator of ciliary beating. Although OAD loss is the most frequent cause of human primary ciliary dyskinesia, the docking mechanism of OAD onto the ciliary doublet microtubule (DMT) remains elusive in vertebrates. Here, we analyzed the functions of Calaxin/Efcab1 and Armc4, the two of five components of vertebrate OAD-DC (docking complex), using zebrafish spermatozoa and cryo-electron tomography. Mutation of armc4 caused complete loss of OAD, whereas mutation of calaxin caused only partial loss of OAD. Detailed structural analysis revealed that calaxin-/- OADs are tethered to DMT through DC components other than Calaxin, and that recombinant Calaxin can autonomously rescue the deficient DC structure and the OAD instability. Our data demonstrate the discrete roles of Calaxin and Armc4 in the OAD-DMT interaction, suggesting the stabilizing process of OAD docking onto DMT in vertebrates.
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Affiliation(s)
- Hiroshi Yamaguchi
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of TokyoTokyoJapan
| | - Motohiro Morikawa
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of TokyoTokyoJapan
| | - Masahide Kikkawa
- Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of TokyoTokyoJapan
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2
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Deligönül N, Yildiz I, Bilgin S, Gokce I, Isildak O. Green Fluorescent Protein-Multi Walled Carbon Nanotube based Polymeric Membrane Electrode for Bismuth Ion Detection. Microchem J 2023. [DOI: 10.1016/j.microc.2023.108710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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3
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Kim H, Choi G, Suk ME, Kim TJ. Resource for FRET-Based Biosensor Optimization. Front Cell Dev Biol 2022; 10:885394. [PMID: 35794864 PMCID: PMC9251444 DOI: 10.3389/fcell.2022.885394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
After the development of Cameleon, the first fluorescence resonance energy transfer (FRET)-based calcium indicator, a variety of FRET-based genetically encoded biosensors (GEBs) have visualized numerous target players to monitor their cell physiological dynamics spatiotemporally. Many attempts have been made to optimize GEBs, which require labor-intensive effort, novel approaches, and precedents to develop more sensitive and versatile biosensors. However, researchers face considerable trial and error in upgrading biosensors because examples and methods of improving FRET-based GEBs are not well documented. In this review, we organize various optimization strategies after assembling the existing cases in which the non-fluorescent components of biosensors are upgraded. In addition, promising areas to which optimized biosensors can be applied are briefly discussed. Therefore, this review could serve as a resource for researchers attempting FRET-based GEB optimization.
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Affiliation(s)
- Heonsu Kim
- Institute of Systems Biology, Pusan National University, Busan, South Korea
| | - Gyuho Choi
- Department of Integrated Biological Science, Pusan National University, Busan, South Korea
| | - Myung Eun Suk
- Department of Mechanical Engineering, IT Convergence College of Materials and Components Engineering, Dong-Eui University, Busan, South Korea
- *Correspondence: Myung Eun Suk, ; Tae-Jin Kim,
| | - Tae-Jin Kim
- Institute of Systems Biology, Pusan National University, Busan, South Korea
- Department of Integrated Biological Science, Pusan National University, Busan, South Korea
- Department of Biological Sciences, Pusan National University, Busan, South Korea
- *Correspondence: Myung Eun Suk, ; Tae-Jin Kim,
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4
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Leem JW, Jeon HJ, Ji Y, Park SM, Kwak Y, Park J, Kim KY, Kim SW, Kim YL. Edible Matrix Code with Photogenic Silk Proteins. ACS CENTRAL SCIENCE 2022; 8:513-526. [PMID: 35647284 PMCID: PMC9136975 DOI: 10.1021/acscentsci.1c01233] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Indexed: 05/28/2023]
Abstract
Counterfeit medicines are a healthcare security problem, posing not only a direct threat to patient safety and public health but also causing heavy economic losses. Current anticounterfeiting methods are limited due to the toxicity of the constituent materials and the focus of secondary packaging level protections. We introduce an edible, imperceptible, and scalable matrix code of information representation and data storage for pharmaceutical products. This matrix code is digestible as it is composed of silk fibroin genetically encoded with fluorescent proteins produced by ecofriendly, sustainable silkworm farming. Three distinct fluorescence emission colors are incorporated into a multidimensional parameter space with a variable encoding capacity in a format of matrix arrays. This code is smartphone-readable to extract a digitized security key augmented by a deep neural network for overcoming fabrication imperfections and a cryptographic hash function for enhanced security. The biocompatibility, photostability, thermal stability, long-term reliability, and low bit error ratio of the code support the immediate feasibility for dosage-level anticounterfeit measures and authentication features. The edible code affixed to each medicine can serve as serialization, track and trace, and authentication at the dosage level, empowering every patient to play a role in combating illicit pharmaceuticals.
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Affiliation(s)
- Jung Woo Leem
- Weldon
School of Biomedical Engineering, Purdue
University, West Lafayette, Indiana 47907, United States
| | - Hee-Jae Jeon
- Weldon
School of Biomedical Engineering, Purdue
University, West Lafayette, Indiana 47907, United States
| | - Yuhyun Ji
- Weldon
School of Biomedical Engineering, Purdue
University, West Lafayette, Indiana 47907, United States
| | - Sang Mok Park
- Weldon
School of Biomedical Engineering, Purdue
University, West Lafayette, Indiana 47907, United States
| | - Yunsang Kwak
- Department
of Mechanical System Engineering, Kumoh
National Institute of Technology, 61 Daehak-ro, Gumi-si, Gyeongsangbuk-do 39177, Republic of Korea
| | - Jongwoo Park
- Department
of Agricultural Biology, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, Jeollabuk-do 55365, Republic of Korea
| | - Kee-Young Kim
- Department
of Agricultural Biology, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, Jeollabuk-do 55365, Republic of Korea
| | - Seong-Wan Kim
- Department
of Agricultural Biology, National Institute of Agricultural Sciences, Rural Development Administration, Wanju, Jeollabuk-do 55365, Republic of Korea
| | - Young L. Kim
- Weldon
School of Biomedical Engineering, Purdue
University, West Lafayette, Indiana 47907, United States
- Purdue
University Center for Cancer Research, West Lafayette, Indiana 47907, United States
- Regenstrief
Center for Healthcare Engineering, West Lafayette, Indiana 47907, United States
- Purdue Quantum
Science and Engineering Institute, West Lafayette, Indiana 47907, United States
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5
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Cornean A, Gierten J, Welz B, Mateo JL, Thumberger T, Wittbrodt J. Precise in vivo functional analysis of DNA variants with base editing using ACEofBASEs target prediction. eLife 2022; 11:72124. [PMID: 35373735 PMCID: PMC9033269 DOI: 10.7554/elife.72124] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Accepted: 03/21/2022] [Indexed: 11/18/2022] Open
Abstract
Single nucleotide variants (SNVs) are prevalent genetic factors shaping individual trait profiles and disease susceptibility. The recent development and optimizations of base editors, rubber and pencil genome editing tools now promise to enable direct functional assessment of SNVs in model organisms. However, the lack of bioinformatic tools aiding target prediction limits the application of base editing in vivo. Here, we provide a framework for adenine and cytosine base editing in medaka (Oryzias latipes) and zebrafish (Danio rerio), ideal for scalable validation studies. We developed an online base editing tool ACEofBASEs (a careful evaluation of base-edits), to facilitate decision-making by streamlining sgRNA design and performing off-target evaluation. We used state-of-the-art adenine (ABE) and cytosine base editors (CBE) in medaka and zebrafish to edit eye pigmentation genes and transgenic GFP function with high efficiencies. Base editing in the genes encoding troponin T and the potassium channel ERG faithfully recreated known cardiac phenotypes. Deep-sequencing of alleles revealed the abundance of intended edits in comparison to low levels of insertion or deletion (indel) events for ABE8e and evoBE4max. We finally validated missense mutations in novel candidate genes of congenital heart disease (CHD) dapk3, ube2b, usp44, and ptpn11 in F0 and F1 for a subset of these target genes with genotype-phenotype correlation. This base editing framework applies to a wide range of SNV-susceptible traits accessible in fish, facilitating straight-forward candidate validation and prioritization for detailed mechanistic downstream studies. DNA contains sequences of four different molecules known as bases that represent our genetic code. In a mutation called a single nucleotide variant (or SNV for short), a single base in the sequence is swapped for another base. This can lead the individual carrying this SNV to produce a slightly different version of a protein to that found in other people. This slightly different protein may not work properly, or may perform a different task. In recent years, researchers have identified thousands of SNVs in humans linked with congenital heart diseases, but the roles of many of these SNVs remain unclear. Tools known as base editors allow researchers to efficiently modify single bases in DNA. Base editors use molecules known as short guide RNAs (or sgRNAs for short) to direct enzymes to specific positions in the DNA to swap, delete or insert a base. The sgRNAs need to be carefully designed to target the correct bases, however, which is a time consuming process. Furthermore, base editors were developed in cells grown in laboratories and so far only a few studies have demonstrated how they could be used in living animals. To overcome these limitations, Cornean, Gierten, Welz et al. developed a framework for base editing in two species of fish that are often used as models in research, namely medaka and zebrafish. The framework uses existing base editors that swap individual target bases and a new online tool – referred to as ACEofBASEs – to help design the required sgRNAs. The team were able to use the framework to characterize the medaka equivalents of four SNVs that have been previously associated with congenital heart disease in humans. The new framework developed here will help researchers to investigate the roles of SNVs in fish and other animals and validate human disease candidates. This approach could also be used to study the various ways that cells modify proteins by changing the specific bases involved in such modifications.
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Affiliation(s)
- Alex Cornean
- Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany
| | - Jakob Gierten
- Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany
| | - Bettina Welz
- Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany
| | - Juan Luis Mateo
- Deparment of Computer Science, University of Oviedo, Oviedo, Spain
| | - Thomas Thumberger
- Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany
| | - Joachim Wittbrodt
- Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany
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6
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Maslakova AA, Didych DA, Golyshev SA, Katrukha IA, Viushkov VS, Zamalutdinov AV, Potashnikova DM, Rubtsov MA, Smirnova OV, Orlovsky IV. Towards unveiling the nature of short SERPINA1 transcripts: Avoiding the main ORF control to translate alpha1-antitrypsin C-terminal peptides. Int J Biol Macromol 2022; 203:703-717. [PMID: 35090941 DOI: 10.1016/j.ijbiomac.2022.01.131] [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: 10/31/2021] [Accepted: 01/19/2022] [Indexed: 11/27/2022]
Abstract
Alternative ORFs in-frame with the known genes are challenging to reveal. Yet they may contribute significantly to proteome diversity. Here we focused on the individual expression of the SERPINA1 gene exon 5 leading to direct translation of alpha1-antitrypsin (AAT) C-terminal peptides. The discovery of alternative ways for their production may expand the current understanding of the serpin gene's functioning. We detected short transcripts expressed primarily in hepatocytes. We identified four variants of hepatocyte-specific SERPINA1 short transcripts and individually probed their potential to be translated in living cells. The long mRNA gave the full-length AAT-eGFP fusion, while in case of short transcripts we deduced four active SERPINA1 in-frame alternative ORFs encoding 10, 21, 153 and 169 amino acids AAT C-terminal oligo- and polypeptides. Unlike secretory AAT-eGFP fusion exhibiting classical AAT behavior, truncated AAT-fusions differ by intracellular retention and nuclear enrichment. Immunofluorescence on the endogenous AAT C-terminal epitope showed its accumulation in the cell nucleoli, indicating that short transcripts may be translated in vivo. FANTOM5 CAGE data on SERPINA1 suggest that short transcripts originate from the post-transcriptional cleavage of the spliced mRNA, initiated mainly from the hepatocyte-specific promoter. CONCLUSION: Short SERPINA1 transcripts may represent a source for the direct synthesis of AAT C-terminal peptides with properties uncommon to AAT.
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Affiliation(s)
- A A Maslakova
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia.
| | - D A Didych
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Miklukho-Maklaya, Moscow 117997, Russia
| | - S A Golyshev
- A.N. Belozersky Research Institute of Physical and Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow 119992, Russia
| | - I A Katrukha
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia; HyTest Ltd., Joukahaisenkatu, Turku 20520, Finland
| | - V S Viushkov
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - A V Zamalutdinov
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - D M Potashnikova
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - M A Rubtsov
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia; I.M. Sechenov First Moscow State Medical University (Sechenov University), Trubetskaya, Moscow 119991, Russia
| | - O V Smirnova
- Faculty of Biology, M.V. Lomonosov Moscow State University, Leninskie Gory, Moscow 119991, Russia
| | - I V Orlovsky
- A.N. Belozersky Research Institute of Physical and Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow 119992, Russia
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7
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Pohl A, Young SAE, Schmitz TC, Farhadi D, Zarivach R, Faivre D, Blank KG. Magnetite-binding proteins from the magnetotactic bacterium Desulfamplus magnetovallimortis BW-1. NANOSCALE 2021; 13:20396-20400. [PMID: 34860229 DOI: 10.1039/d1nr04870h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Magnetite-binding proteins are in high demand for the functionalization of magnetic nanoparticles. Binding analysis of six previously uncharacterized proteins from the magnetotactic Deltaproteobacterium Desulfamplus magnetovallimortis BW-1 identified two new magnetite-binding proteins (Mad10, Mad11). These proteins can be utilized as affinity tags for the immobilization of recombinant fusion proteins to magnetite.
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Affiliation(s)
- Anna Pohl
- Max Planck Institute of Colloids and Interfaces, Mechano(bio)chemistry, Am Mühlenberg 1, 14476 Potsdam, Germany.
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Am Mühlenberg 1, 14476 Potsdam, Germany.
| | - Sarah A E Young
- Max Planck Institute of Colloids and Interfaces, Mechano(bio)chemistry, Am Mühlenberg 1, 14476 Potsdam, Germany.
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Am Mühlenberg 1, 14476 Potsdam, Germany.
| | - Tara C Schmitz
- Max Planck Institute of Colloids and Interfaces, Mechano(bio)chemistry, Am Mühlenberg 1, 14476 Potsdam, Germany.
| | - Daniel Farhadi
- Max Planck Institute of Colloids and Interfaces, Mechano(bio)chemistry, Am Mühlenberg 1, 14476 Potsdam, Germany.
| | - Raz Zarivach
- Department of Life Sciences, The National Institute for Biotechnology in the Negev and Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel
| | - Damien Faivre
- Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Am Mühlenberg 1, 14476 Potsdam, Germany.
- Aix-Marseille Université, CEA, CNRS, BIAM, 13108 Saint Paul lez Durance, France
| | - Kerstin G Blank
- Max Planck Institute of Colloids and Interfaces, Mechano(bio)chemistry, Am Mühlenberg 1, 14476 Potsdam, Germany.
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8
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Vongsouthi V, Whitfield JH, Unichenko P, Mitchell JA, Breithausen B, Khersonsky O, Kremers L, Janovjak H, Monai H, Hirase H, Fleishman SJ, Henneberger C, Jackson CJ. A Rationally and Computationally Designed Fluorescent Biosensor for d-Serine. ACS Sens 2021; 6:4193-4205. [PMID: 34783546 DOI: 10.1021/acssensors.1c01803] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Solute-binding proteins (SBPs) have evolved to balance the demands of ligand affinity, thermostability, and conformational change to accomplish diverse functions in small molecule transport, sensing, and chemotaxis. Although the ligand-induced conformational changes that occur in SBPs make them useful components in biosensors, they are challenging targets for protein engineering and design. Here, we have engineered a d-alanine-specific SBP into a fluorescence biosensor with specificity for the signaling molecule d-serine (D-serFS). This was achieved through binding site and remote mutations that improved affinity (KD = 6.7 ± 0.5 μM), specificity (40-fold increase vs glycine), thermostability (Tm = 79 °C), and dynamic range (∼14%). This sensor allowed measurement of physiologically relevant changes in d-serine concentration using two-photon excitation fluorescence microscopy in rat brain hippocampal slices. This work illustrates the functional trade-offs between protein dynamics, ligand affinity, and thermostability and how these must be balanced to achieve desirable activities in the engineering of complex, dynamic proteins.
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Affiliation(s)
- Vanessa Vongsouthi
- Research School of Chemistry, Australian National University, Canberra 2601, Australia
| | - Jason H. Whitfield
- Research School of Chemistry, Australian National University, Canberra 2601, Australia
| | - Petr Unichenko
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn 53127, Germany
| | - Joshua A. Mitchell
- Research School of Chemistry, Australian National University, Canberra 2601, Australia
| | - Björn Breithausen
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn 53127, Germany
| | - Olga Khersonsky
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Leon Kremers
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn 53127, Germany
| | - Harald Janovjak
- Australian Regenerative Medicine Institute (ARMI), Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton/Melbourne 3800, Australia
| | - Hiromu Monai
- Laboratory for Neuron-Glia Circuitry, RIKEN Center for Brain Science, Wako 351-0198, Japan
| | - Hajime Hirase
- Laboratory for Neuron-Glia Circuitry, RIKEN Center for Brain Science, Wako 351-0198, Japan
| | - Sarel J. Fleishman
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Christian Henneberger
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn 53127, Germany
- Institute of Neurology, University College London, London WC1N 3BG, United Kingdom
- German Center for Degenerative Diseases (DZNE), Bonn 53127, Germany
| | - Colin J. Jackson
- Research School of Chemistry, Australian National University, Canberra 2601, Australia
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9
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Worst EG, Finkler M, Schenkelberger M, Kurt Ö, Helms V, Noireaux V, Ott A. A Methylation-Directed, Synthetic Pap Switch Based on Self-Complementary Regulatory DNA Reconstituted in an All E. coli Cell-Free Expression System. ACS Synth Biol 2021; 10:2725-2739. [PMID: 34550672 DOI: 10.1021/acssynbio.1c00326] [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: 11/29/2022]
Abstract
Pyelonephritis-associated pili (pap) enable migration of the uropathogenic Escherichia coli strain (UPEC) through the urinary tract. UPEC can switch between a stable 'ON phase' where the corresponding pap genes are expressed and a stable 'OFF phase' where their transcription is repressed. Hereditary DNA methylation of either one of two GATC motives within the regulatory region stabilizes the respective phase over many generations. The underlying molecular mechanism is only partly understood. Previous investigations suggest that in vivo phase-variation stability results from cooperative action of the transcriptional regulators Lrp and PapI. Here, we use an E. coli cell-free expression system to study molecular functions of the pap regulatory region based on a specially designed, synthetic construct flanked by two reporter genes encoding fluorescent proteins for simple readout. On the basis of our observations we suggest that besides Lrp, the conformation of the self-complementary regulatory DNA plays a strong role in the regulation of phase-variation. Our work not only contributes to better understand the phase variation mechanism, but it represents a successful start for mimicking stable, hereditary, and strong expression control based on methylation. The conformation of the regulatory DNA corresponds to a Holliday junction. Gene expression must be expected to respond if opposite arms of the junction are drawn outward.
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Affiliation(s)
- Emanuel G. Worst
- Universität des Saarlandes, Center for Biophysics, Saarbrücken, 66123, Germany
| | - Marc Finkler
- Universität des Saarlandes, Center for Biophysics, Saarbrücken, 66123, Germany
| | - Marc Schenkelberger
- Universität des Saarlandes, Center for Biophysics, Saarbrücken, 66123, Germany
| | - Ömer Kurt
- Universität des Saarlandes, Center for Biophysics, Saarbrücken, 66123, Germany
| | - Volkhard Helms
- Universität des Saarlandes, Center for Bioinformatics, Saarbrücken, 66041, Germany
| | - Vincent Noireaux
- University of Minnesota, School of Physics and Astronomy, Minneapolis, Minnesota 55455, United States
| | - Albrecht Ott
- Universität des Saarlandes, Center for Biophysics, Saarbrücken, 66123, Germany
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10
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TRIM28 is a transcriptional activator of the mutant TERT promoter in human bladder cancer. Proc Natl Acad Sci U S A 2021; 118:2102423118. [PMID: 34518220 DOI: 10.1073/pnas.2102423118] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/30/2021] [Indexed: 12/20/2022] Open
Abstract
Bladder cancer (BC) has a 70% telomerase reverse transcriptase (TERT or hTERT in humans) promoter mutation prevalence, commonly at -124 base pairs, and this is associated with increased hTERT expression and poor patient prognosis. We inserted a green fluorescent protein (GFP) tag in the mutant hTERT promoter allele to create BC cells expressing an hTERT-GFP fusion protein. These cells were used in a fluorescence-activated cell sorting-based pooled CRISPR-Cas9 Kinome knockout genetic screen to identify tripartite motif containing 28 (TRIM28) and TRIM24 as regulators of hTERT expression. TRIM28 activates, while TRIM24 suppresses, hTERT transcription from the mutated promoter allele. TRIM28 is recruited to the mutant promoter where it interacts with TRIM24, which inhibits its activity. Phosphorylation of TRIM28 through the mTOR complex 1 (mTORC1) releases it from TRIM24 and induces hTERT transcription. TRIM28 expression promotes in vitro and in vivo BC cell growth and stratifies BC patient outcome. mTORC1 inhibition with rapamycin analog Ridaforolimus suppresses TRIM28 phosphorylation, hTERT expression, and cell viability. This study may lead to hTERT-directed cancer therapies with reduced effects on normal progenitor cells.
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11
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Zhang D, Wang Z, Hu S, Balamkundu S, To J, Zhang X, Lescar J, Tam JP, Liu CF. pH-Controlled Protein Orthogonal Ligation Using Asparaginyl Peptide Ligases. J Am Chem Soc 2021; 143:8704-8712. [PMID: 34096285 DOI: 10.1021/jacs.1c02638] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Peptide asparaginyl ligases (PALs) catalyze transpeptidation at the Asn residue of a short Asn-Xaa1-Xaa2 tripeptide motif. Due to their high catalytic activity toward the P1-Asn substrates at around neutral pH, PALs have been used extensively for peptide ligation at asparaginyl junctions. PALs also bind to aspartyl substrates, but only when the γCOOH of P1-Asp remains in its neutral, protonated form, which usually requires an acidic pH. However, this limits the availability of the amine nucleophile and, consequently, the ligation efficiency at aspartyl junctions. Because of this perceived inefficiency, the use of PALs for Asp-specific ligation remains largely unexplored. We found that PAL enzymes, such as VyPAL2, display appreciable catalytic activities toward P1-Asp substrates at pH 4-5, which are at least 2 orders of magnitude higher than that of sortase A, making them practically useful for both intra- and intermolecular ligations. This also allows sequential ligations, first at Asp and then at Asn junctions, because the newly formed aspartyl peptide bond is resistant to the ligase at the pH used for asparaginyl ligation in the second step. Using this pH-controlled orthogonal ligation method, we dually labeled truncated sfGFP with a cancer-targeting peptide and a doxorubicin derivative at the respective N- and C-terminal ends in the N-to-C direction. In addition, a fluorescein tag and doxorubicin derivative were tagged to an EGFR-targeting affibody in the C-to-N direction. This study shows that the pH-dependent catalytic activity of PAL enzymes can be exploited to prepare multifunction protein biologics for pharmacological applications.
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Affiliation(s)
- Dingpeng Zhang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Zhen Wang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Side Hu
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | | | - Janet To
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Xiaohong Zhang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Julien Lescar
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - James P Tam
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Chuan-Fa Liu
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
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12
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Sadoine M, Reger M, Wong KM, Frommer WB. Affinity Series of Genetically Encoded Förster Resonance Energy-Transfer Sensors for Sucrose. ACS Sens 2021; 6:1779-1784. [PMID: 33974799 DOI: 10.1021/acssensors.0c02495] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Genetically encoded fluorescent sugar sensors are valuable tools for the discovery of transporters and for quantitative monitoring of sugar steady-state levels in intact tissues. Genetically encoded Förster resonance energy-transfer sensors for glucose have been designed and optimized extensively, and a full series of affinity mutants is available for in vivo studies. However, to date, only a single improved sucrose sensor FLIPsuc-90μΔ1 with Km for sucrose of ∼90 μM was available. This sucrose sensor was engineered on the basis of an Agrobacterium tumefaciens sugar-binding protein. Here, we took a two-step approach to first improve the dynamic range of the FLIPsuc sensor and then expand the detection range from micro- to millimolar sucrose concentrations by mutating a key residue in the binding site. The resulting series of sucrose sensors may enable investigation of sucrose transporter candidates and comprehensive in vivo analyses of sucrose concentration in plants. Since FLIPsuc-90μ also detects trehalose in animal cells, the new series of sensors will likely be suitable for investigating trehalose transport and monitor trehalose steady-state levels in vivo.
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Affiliation(s)
- Mayuri Sadoine
- Institute for Molecular Physiology, Heinrich Heine University Düsseldorf, Düsseldorf 40225, Germany
| | - Mira Reger
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, United States
| | - Ka Man Wong
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, United States
| | - Wolf B. Frommer
- Institute for Molecular Physiology, Heinrich Heine University Düsseldorf, Düsseldorf 40225, Germany
- Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305, United States
- Institute for Transformative Biomolecules, ITbM, Nagoya University, Nagoya, Aichi 464-8601, Japan
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13
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Song B, Kang CY, Han JH, Kano M, Konnerth A, Bae S. In vivo genome editing in single mammalian brain neurons through CRISPR-Cas9 and cytosine base editors. Comput Struct Biotechnol J 2021; 19:2477-2485. [PMID: 34025938 PMCID: PMC8113754 DOI: 10.1016/j.csbj.2021.04.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 04/20/2021] [Accepted: 04/22/2021] [Indexed: 10/31/2022] Open
Abstract
Gene manipulation is a useful approach for understanding functions of genes and is important for investigating basic mechanisms of brain function on the level of single neurons and circuits. Despite the development and the wide range of applications of CRISPR-Cas9 and base editors (BEs), their implementation for an analysis of individual neurons in vivo remained limited. In fact, conventional gene manipulations are generally achieved only on the population level. Here, we combined either CRISPR-Cas9 or BEs with the targeted single-cell electroporation technique as a proof-of-concept test for gene manipulation in single neurons in vivo. Our assay consisted of CRISPR-Cas9- or BEs-induced gene knockout in single Purkinje cells in the cerebellum. Our results demonstrate the feasibility of both gene editing and base editing in single cells in the intact brain, providing a tool through which molecular perturbations of individual neurons can be used for analysis of circuits and, ultimately, behaviors.
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Affiliation(s)
- Beomjong Song
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Chan Young Kang
- Department of Chemistry and Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 04763, South Korea
| | - Jun Hee Han
- Department of Chemistry and Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 04763, South Korea
| | - Masanobu Kano
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.,Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Arthur Konnerth
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.,Institute of Neuroscience, Technical University of Munich, 80802 Munich, Germany.,Munich Cluster for Systems Neurology, Technical University of Munich, 80802 Munich, Germany
| | - Sangsu Bae
- Department of Chemistry and Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 04763, South Korea
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14
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Doshi J, Willis K, Madurga A, Stelzer C, Benenson Y. Multiple Alternative Promoters and Alternative Splicing Enable Universal Transcription-Based Logic Computation in Mammalian Cells. Cell Rep 2020; 33:108437. [PMID: 33264624 DOI: 10.1016/j.celrep.2020.108437] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 09/04/2020] [Accepted: 11/05/2020] [Indexed: 10/22/2022] Open
Abstract
Multi-input logic gene circuits can enable sophisticated control of cell function, yet large-scale synthetic circuitry in mammalian cells has relied on post-transcriptional regulation or recombinase-triggered state transitions. Large-scale transcriptional logic, on the other hand, has been challenging to implement. Inspired by a naturally found regulatory strategy of using multiple alternative promoters, followed by alternative splicing, we developed a scalable and compact platform for transcriptional OR logic using inputs to those promoters. The platform is extended to implement disjunctive normal form (DNF) computations capable of implementing arbitrary logic rules. Specifically, AND logic is implemented at individual promoters using synergistic transcriptional inputs, and NOT logic via microRNA inputs targeting unique exon sequences driven by those promoters. Together, these regulatory programs result in DNF-like logic control of output gene expression. The approach offers flexibility for building complex logic programs in mammalian cells.
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Affiliation(s)
- Jiten Doshi
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Katie Willis
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Angela Madurga
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Christoph Stelzer
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Yaakov Benenson
- Department of Biosystems Science and Engineering, ETH Zurich, Mattenstrasse 26, 4058 Basel, Switzerland.
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15
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Valbuena FM, Fitzgerald I, Strack RL, Andruska N, Smith L, Glick BS. A photostable monomeric superfolder green fluorescent protein. Traffic 2020; 21:534-544. [PMID: 32415747 DOI: 10.1111/tra.12737] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 05/09/2020] [Accepted: 05/10/2020] [Indexed: 11/30/2022]
Abstract
The green fluorescent protein (GFP) from Aequorea victoria has been engineered extensively in the past to generate variants suitable for protein tagging. Early efforts produced the enhanced variant EGFP and its monomeric derivative mEGFP, which have useful photophysical properties, as well as superfolder GFP, which folds efficiently under adverse conditions. We previously generated msGFP, a monomeric superfolder derivative of EGFP. Unfortunately, compared to EGFP, msGFP and other superfolder GFP variants show faster photobleaching. We now describe msGFP2, which retains monomeric superfolder properties while being as photostable as EGFP. msGFP2 contains modified N- and C-terminal peptides that are expected to reduce nonspecific interactions. Compared to EGFP and mEGFP, msGFP2 is less prone to disturbing the functions of certain partner proteins. For general-purpose protein tagging, msGFP2 may be the best available derivative of A. victoria GFP.
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Affiliation(s)
- Fernando M Valbuena
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Ivy Fitzgerald
- Graduate Program in Biophysical Sciences, The University of Chicago, Chicago, Illinois, USA
| | - Rita L Strack
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Neal Andruska
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Luke Smith
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Benjamin S Glick
- Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, Illinois, USA
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16
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Koscielniak D, Wons E, Wilkowska K, Sektas M. Non-programmed transcriptional frameshifting is common and highly RNA polymerase type-dependent. Microb Cell Fact 2018; 17:184. [PMID: 30474557 PMCID: PMC6260861 DOI: 10.1186/s12934-018-1034-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 11/19/2018] [Indexed: 12/15/2022] Open
Abstract
Background The viral or host systems for a gene expression assume repeatability of the process and high quality of the protein product. Since level and fidelity of transcription primarily determines the overall efficiency, all factors contributing to their decrease should be identified and optimized. Among many observed processes, non-programmed insertion/deletion (indel) of nucleotide during transcription (slippage) occurring at homopolymeric A/T sequences within a gene can considerably impact its expression. To date, no comparative study of the most utilized Escherichia coli and T7 bacteriophage RNA polymerases (RNAP) propensity for this type of erroneous mRNA synthesis has been reported. To address this issue we evaluated the influence of shift-prone A/T sequences by assessing indel-dependent phenotypic changes. RNAP-specific expression profile was examined using two of the most potent promoters, ParaBAD of E. coli and φ10 of phage T7. Results Here we report on the first systematic study on requirements for efficient transcriptional slippage by T7 phage and cellular RNAPs considering three parameters: homopolymer length, template type, and frameshift directionality preferences. Using a series of out-of-frame gfp reporter genes fused to a variety of A/T homopolymeric sequences we show that T7 RNAP has an exceptional potential for generating frameshifts and is capable of slipping on as few as three adenine or four thymidine residues in a row, in a flanking sequence-dependent manner. In contrast, bacterial RNAP exhibits a relatively low ability to baypass indel mutations and requires a run of at least 7 tymidine and even more adenine residues. This difference comes from involvement of various intrinsic proofreading properties. Our studies demonstrate distinct preference towards a specific homopolymer in slippage induction. Whereas insertion slippage performed by T7 RNAP (but not deletion) occurs tendentiously on poly(A) rather than on poly(T) runs, strong bias towards poly(T) for the host RNAP is observed. Conclusions Intrinsic RNAP slippage properties involve trade-offs between accuracy, speed and processivity of transcription. Viral T7 RNAP manifests far greater inclinations to the transcriptional slippage than E. coli RNAP. This possibly plays an important role in driving bacteriophage adaptation and therefore could be considered as beneficial. However, from biotechnological and experimental viewpoint, this might create some problems, and strongly argues for employing bacterial expression systems, stocked with proofreading mechanisms. Electronic supplementary material The online version of this article (10.1186/s12934-018-1034-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dawid Koscielniak
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland
| | - Ewa Wons
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland
| | - Karolina Wilkowska
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland
| | - Marian Sektas
- Department of Microbiology, Faculty of Biology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland.
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17
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Hamidi SR, Safdari Y, Sheikh Arabi M. Test bacterial inclusion body for activity prior to start denaturing and refolding processes to obtain active eukaryotic proteins. Protein Expr Purif 2018; 154:147-151. [PMID: 30389592 DOI: 10.1016/j.pep.2018.10.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 10/27/2018] [Accepted: 10/30/2018] [Indexed: 02/05/2023]
Abstract
One of a major drawbacks correlated with expressing antibody fragments in bacterial cells is insolubility, which is often regarded as an obstacle in obtaining active molecules. Recombinant proteins aggregated as inclusion bodies within bacterial cells are thought to be unfolded or misfolded, and therefore inactive. So, denaturing and refolding strategies, which are laborious and sometime inefficient, are used to obtain correctly-folded active proteins. In the current study, we show that large quantities of correctly folded and completely active scFv molecules are there in bacterial inclusion bodies; they only need to be isolated from inclusion bodies.
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Affiliation(s)
- Seyedeh Roghayeh Hamidi
- Department of Medical Biotechnology, Faculty of Advanced Technologies in Medicine, Golestan University of Medical Sciences, Gorgan, Iran
| | - Yaghoub Safdari
- Medical Cellular and Molecular Research Center, Golestan University of Medical Sciences, Gorgan, Iran.
| | - Mehdi Sheikh Arabi
- Medical Cellular and Molecular Research Center, Golestan University of Medical Sciences, Gorgan, Iran
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18
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Wons E, Koscielniak D, Szadkowska M, Sektas M. Evaluation of GFP reporter utility for analysis of transcriptional slippage during gene expression. Microb Cell Fact 2018; 17:150. [PMID: 30241530 PMCID: PMC6149199 DOI: 10.1186/s12934-018-0999-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 09/17/2018] [Indexed: 11/20/2022] Open
Abstract
Background Epimutations arising from transcriptional slippage seem to have more important role in regulating gene expression than earlier though. Since the level and the fidelity of transcription primarily determine the overall efficiency of gene expression, all factors contributing to their decrease should be identified and optimized. Results To examine the influence of A/T homopolymeric sequences on introduction of erroneous nucleotides by slippage mechanism green fluorescence protein (GFP) reporter was chosen. The in- or out-of-frame gfp gene was fused to upstream fragment with variable number of adenine or thymine stretches resulting in several hybrid GFP proteins with diverse amino acids at N-terminus. Here, by using T7 phage expression system we showed that the intensity of GFP fluorescence mainly depends on the number of the retained natural amino acids. While the lack of serine (S2) residue results in negligible effects, the lack of serine and lysine (S2K3) contributed to a significant reduction in fluorescence by 2.7-fold for polyA-based in-frame controls and twofold for polyTs. What is more, N-terminal tails amino acid composition was rather of secondary importance, since the whole-cell fluorescence differed in a range of 9–18% between corresponding polyA- and polyT-based constructs. Conclusions Here we present experimental evidence for utility of GFP reporter for accurate estimation of A/T homopolymeric sequence contribution in transcriptional slippage induction. We showed that the intensity of GFP hybrid fluorescence mainly depends on the number of retained natural amino acids, thus fluorescence raw data need to be referred to appropriate positive control. Moreover, only in case of GFP hybrids with relatively short N-terminal tags the fluorescence level solely reflects production yield, what further indicates the impact of an individual slippage sequence. Our results demonstrate that in contrast to the E. coli enzyme, T7 RNA polymerase exhibits extremely high propensity to slippage even on runs as short as 3 adenine or 4 thymine residues. Electronic supplementary material The online version of this article (10.1186/s12934-018-0999-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ewa Wons
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland
| | - Dawid Koscielniak
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland
| | - Monika Szadkowska
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland
| | - Marian Sektas
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, 80-308, Gdansk, Poland.
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19
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LaCroix AS, Lynch AD, Berginski ME, Hoffman BD. Tunable molecular tension sensors reveal extension-based control of vinculin loading. eLife 2018; 7:33927. [PMID: 30024378 PMCID: PMC6053308 DOI: 10.7554/elife.33927] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 06/03/2018] [Indexed: 01/03/2023] Open
Abstract
Molecular tension sensors have contributed to a growing understanding of mechanobiology. However, the limited dynamic range and inability to specify the mechanical sensitivity of these sensors has hindered their widespread use in diverse contexts. Here, we systematically examine the components of tension sensors that can be altered to improve their functionality. Guided by the development of a first principles model describing the mechanical behavior of these sensors, we create a collection of sensors that exhibit predictable sensitivities and significantly improved performance in cellulo. Utilized in the context of vinculin mechanobiology, a trio of these new biosensors with distinct force- and extension-sensitivities reveal that an extension-based control paradigm regulates vinculin loading in a variety of mechanical contexts. To enable the rational design of molecular tension sensors appropriate for diverse applications, we predict the mechanical behavior, in terms of force and extension, of additional 1020 distinct designs. Cells must sense signals from their surroundings to play their roles within the body. These signals can be biochemical, such as growth-promoting substances, or mechanical, for example the stiffness or softness of the environment. Mechanical signals can be detected by load-bearing proteins, which stretch like tiny springs in response to forces. In animals, these proteins span the membrane separating the interior of the cell from the exterior. Externally, the proteins attach to structures around the cell; internally, they connect to the machinery that both generates forces and allows cells to respond to signals from outside. As such, load-bearing proteins form a direct mechanical link between cell and environment. Scientists use tools called molecular tension sensors to measure how much a load-bearing protein stretches in response to changes, and the force that is being applied to it. However, just like any other type of scale, these sensors only work over a certain range, which happens to be limited. This means that, for example, they cannot measure forces in tissues that are too soft (like the brain), or too stiff (such as bones). New sensors that can assess forces in these contexts are therefore needed, but so far research in this area has been slow due to a reliance on ‘trial-and-error’ approaches. Here, LaCroix et al. developed a new method to predict the sensitivity of molecular tension sensors inside cells. This was accomplished by examining several existing sensors, and identifying which components could be altered to change the properties of the sensors. Then, this information was used to create a computer model that could predict how new sensors would behave, and which range of forces they could measure. Finally, the sensors designed following this method were tested in mouse cells grown in the laboratory, and they worked better than their predecessors. The next step was for LaCroix et al. to use a trio of new sensors with different sensitivities to study the load-bearing protein vinculin in mouse cells. The goal was to figure out exactly how cells manage their load-bearing proteins. Indeed, it was widely assumed that a cell acts on a load-bearing protein by applying a force on it. In response, the protein would stretch by a certain amount, which can change depending on its properties – a ‘stiffer’ protein would stretch less. Unexpectedly, the new sensors showed that cells instead manipulate how much vinculin stretches, applying varying forces to achieve the same length of the protein in different environments. Improved molecular tension sensors will give scientists a better insight into how cells respond to their mechanical environment, which could help to direct cell behavior in tissues engineered in the laboratory. This knowledge is also directly relevant to human health, as the mechanical properties of many tissues change during disease, such as tumors stiffening during cancer.
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Affiliation(s)
- Andrew S LaCroix
- Department of Biomedical Engineering, Duke University, Durham, United States
| | - Andrew D Lynch
- Department of Biomedical Engineering, Duke University, Durham, United States
| | - Matthew E Berginski
- Department of Biomedical Engineering, Duke University, Durham, United States
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, United States
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20
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Gaytán P, Roldán-Salgado A, Yáñez JA, Morales-Arrieta S, Juárez-González VR. CiPerGenesis, A Mutagenesis Approach that Produces Small Libraries of Circularly Permuted Proteins Randomly Opened at a Focused Region: Testing on the Green Fluorescent Protein. ACS COMBINATORIAL SCIENCE 2018; 20:400-413. [PMID: 29812897 DOI: 10.1021/acscombsci.7b00152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Circularly permuted proteins (cpPs) represent a novel type of mutant proteins with original termini that are covalently linked through a peptide connector and opened at any other place of the polypeptide backbone to create new ends. cpPs are finding wide applications in biotechnology because their properties may be quite different from those of the parental protein. However, the actual challenge for the creation of successful cpPs is to identify those peptide bonds that can be broken to create new termini and ensure functional and well-folded cpPs. Herein, we describe CiPerGenesis, a combinatorial mutagenesis approach that uses two oligonucleotide libraries to amplify a circularized gene by PCR, starting and ending from a focused target region. This approach creates small libraries of circularly permuted genes that are easily cloned in the correct direction and frame using two different restriction sites encoded in the oligonucleotides. Once expressed, the protein libraries exhibit a unique sequence diversity, comprising cpPs that exhibit ordinary breakpoints between adjacent amino acids localized at the target region as well as cpPs with new termini containing user-defined truncations and repeats of some amino acids. CiPerGenesis was tested at the lid region G134-H148 of green fluorescent protein (GFP), revealing that the most fluorescent variants were those starting at Leu141 and ending at amino acids Tyr145, Tyr143, Glu142, Leu141, Lys140, and H139. Purification and biochemical characterization of some variants suggested a differential expression, solubility and maturation extent of the mutant proteins as the likely cause for the variability in fluorescence intensity observed in colonies.
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Affiliation(s)
- Paul Gaytán
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Cuernavaca, Morelos 62210, México
| | - Abigail Roldán-Salgado
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Cuernavaca, Morelos 62210, México
| | - Jorge A. Yáñez
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Cuernavaca, Morelos 62210, México
| | - Sandra Morales-Arrieta
- Departamento de Ingeniería en Biotecnología, Universidad Politécnica del Estado de Morelos, Boulevard Cuauhnáhuac No. 566, Col. Lomas del Texcal, Jiutepec, Morelos 62550, México
| | - Víctor R. Juárez-González
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Avenida Universidad 2001, Cuernavaca, Morelos 62210, México
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21
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Hecht A, Glasgow J, Jaschke PR, Bawazer LA, Munson MS, Cochran JR, Endy D, Salit M. Measurements of translation initiation from all 64 codons in E. coli. Nucleic Acids Res 2017; 45:3615-3626. [PMID: 28334756 PMCID: PMC5397182 DOI: 10.1093/nar/gkx070] [Citation(s) in RCA: 100] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Accepted: 01/25/2017] [Indexed: 12/21/2022] Open
Abstract
Our understanding of translation underpins our capacity to engineer living systems. The canonical start codon (AUG) and a few near-cognates (GUG, UUG) are considered as the ‘start codons’ for translation initiation in Escherichia coli. Translation is typically not thought to initiate from the 61 remaining codons. Here, we quantified translation initiation of green fluorescent protein and nanoluciferase in E. coli from all 64 triplet codons and across a range of DNA copy number. We detected initiation of protein synthesis above measurement background for 47 codons. Translation from non-canonical start codons ranged from 0.007 to 3% relative to translation from AUG. Translation from 17 non-AUG codons exceeded the highest reported rates of non-cognate codon recognition. Translation initiation from non-canonical start codons may contribute to the synthesis of peptides in both natural and synthetic biological systems.
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Affiliation(s)
- Ariel Hecht
- Joint Initiative for Metrology in Biology, Stanford, CA 94305, USA.,Genome-scale Measurements Group, National Institute of Standards and Technology, Stanford, CA 94305, USA.,Department of Bioengineering, Stanford, CA 94305, USA
| | - Jeff Glasgow
- Joint Initiative for Metrology in Biology, Stanford, CA 94305, USA.,Genome-scale Measurements Group, National Institute of Standards and Technology, Stanford, CA 94305, USA.,Department of Bioengineering, Stanford, CA 94305, USA
| | - Paul R Jaschke
- Department of Bioengineering, Stanford, CA 94305, USA.,Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Lukmaan A Bawazer
- Joint Initiative for Metrology in Biology, Stanford, CA 94305, USA.,Genome-scale Measurements Group, National Institute of Standards and Technology, Stanford, CA 94305, USA.,Department of Bioengineering, Stanford, CA 94305, USA
| | - Matthew S Munson
- Joint Initiative for Metrology in Biology, Stanford, CA 94305, USA.,Genome-scale Measurements Group, National Institute of Standards and Technology, Stanford, CA 94305, USA.,Department of Bioengineering, Stanford, CA 94305, USA
| | - Jennifer R Cochran
- Joint Initiative for Metrology in Biology, Stanford, CA 94305, USA.,Department of Bioengineering, Stanford, CA 94305, USA
| | - Drew Endy
- Joint Initiative for Metrology in Biology, Stanford, CA 94305, USA.,Department of Bioengineering, Stanford, CA 94305, USA
| | - Marc Salit
- Joint Initiative for Metrology in Biology, Stanford, CA 94305, USA.,Genome-scale Measurements Group, National Institute of Standards and Technology, Stanford, CA 94305, USA.,Department of Bioengineering, Stanford, CA 94305, USA
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22
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Scanlon DP, Bah A, Krzeminski M, Zhang W, Leduc-Pessah HL, Dong YN, Forman-Kay JD, Salter MW. An evolutionary switch in ND2 enables Src kinase regulation of NMDA receptors. Nat Commun 2017; 8:15220. [PMID: 28508887 PMCID: PMC5440837 DOI: 10.1038/ncomms15220] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/10/2017] [Indexed: 12/22/2022] Open
Abstract
The non-receptor tyrosine kinase Src is a key signalling hub for upregulating the function of N-methyl D-aspartate receptors (NMDARs). Src is anchored within the NMDAR complex via NADH dehydrogenase subunit 2 (ND2), a mitochondrially encoded adaptor protein. The interacting regions between Src and ND2 have been broadly identified, but the interaction between ND2 and the NMDAR has remained elusive. Here we generate a homology model of ND2 and dock it onto the NMDAR via the transmembrane domain of GluN1. This interaction is enabled by the evolutionary loss of three helices in bilaterian ND2 proteins compared to their ancestral homologues. We experimentally validate our model and demonstrate that blocking this interaction with an ND2 fragment identified in our experimental studies prevents Src-mediated upregulation of NMDAR currents in neurons. Our findings establish the mode of interaction between an NMDAR accessory protein with one of the core subunits of the receptor. N-methyl D-aspartate receptor (NMDAR) activity is modulated by Src tyrosine kinase via the mitochondrial protein NADH dehydrogenase subunit 2 (ND2). Here the authors show that ND2 interacts with the transmembrane region of NMDAR GluN1 subunit, a process that is crucial for Src regulation of NMDAR activity.
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Affiliation(s)
- David P Scanlon
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Alaji Bah
- Program in Molecular Medicine, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Mickaël Krzeminski
- Program in Molecular Medicine, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Wenbo Zhang
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Heather L Leduc-Pessah
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Yi Na Dong
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Julie D Forman-Kay
- Program in Molecular Medicine, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
| | - Michael W Salter
- Program in Neurosciences &Mental Health, The Hospital for Sick Children, 686 Bay St, Toronto, Ontario, Canada M5G 0A4.,Department of Physiology, University of Toronto, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
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Schenkelberger M, Shanak S, Finkler M, Worst EG, Noireaux V, Helms V, Ott A. Expression regulation by a methyl-CpG binding domain in anE. colibased, cell-free TX-TL system. Phys Biol 2017; 14:026002. [DOI: 10.1088/1478-3975/aa5d37] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Probing for Binding Regions of the FtsZ Protein Surface through Site-Directed Insertions: Discovery of Fully Functional FtsZ-Fluorescent Proteins. J Bacteriol 2016; 199:JB.00553-16. [PMID: 27795325 DOI: 10.1128/jb.00553-16] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 10/04/2016] [Indexed: 11/20/2022] Open
Abstract
FtsZ, a bacterial tubulin homologue, is a cytoskeletal protein that assembles into protofilaments that are one subunit thick. These protofilaments assemble further to form a "Z ring" at the center of prokaryotic cells. The Z ring generates a constriction force on the inner membrane and also serves as a scaffold to recruit cell wall remodeling proteins for complete cell division in vivo One model of the Z ring proposes that protofilaments associate via lateral bonds to form ribbons; however, lateral bonds are still only hypothetical. To explore potential lateral bonding sites, we probed the surface of Escherichia coli FtsZ by inserting either small peptides or whole fluorescent proteins (FPs). Among the four lateral surfaces on FtsZ protofilaments, we obtained inserts on the front and back surfaces that were functional for cell division. We concluded that these faces are not sites of essential interactions. Inserts at two sites, G124 and R174, located on the left and right surfaces, completely blocked function, and these sites were identified as possible sites for essential lateral interactions. However, the insert at R174 did not interfere with association of protofilaments into sheets and bundles in vitro Another goal was to find a location within FtsZ that supported insertion of FP reporter proteins while allowing the FtsZ-FPs to function as the sole source of FtsZ. We discovered one internal site, G55-Q56, where several different FPs could be inserted without impairing function. These FtsZ-FPs may provide advances for imaging Z-ring structure by superresolution techniques. IMPORTANCE One model for the Z-ring structure proposes that protofilaments are assembled into ribbons by lateral bonds between FtsZ subunits. Our study excluded the involvement of the front and back faces of the protofilament in essential interactions in vivo but pointed to two potential lateral bond sites, on the right and left sides. We also identified an FtsZ loop where various fluorescent proteins could be inserted without blocking function; these FtsZ-FPs functioned as the sole source of FtsZ. This advance provides improved tools for all fluorescence imaging of the Z ring and may be especially important for superresolution imaging.
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25
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Endow JK, Rocha AG, Baldwin AJ, Roston RL, Yamaguchi T, Kamikubo H, Inoue K. Polyglycine Acts as a Rejection Signal for Protein Transport at the Chloroplast Envelope. PLoS One 2016; 11:e0167802. [PMID: 27936133 PMCID: PMC5147994 DOI: 10.1371/journal.pone.0167802] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 11/21/2016] [Indexed: 11/19/2022] Open
Abstract
PolyGly is present in many proteins in various organisms. One example is found in a transmembrane β-barrel protein, translocon at the outer-envelope-membrane of chloroplasts 75 (Toc75). Toc75 requires its N-terminal extension (t75) for proper localization. t75 comprises signals for chloroplast import (n75) and envelope sorting (c75) in tandem. n75 and c75 are removed by stromal processing peptidase and plastidic type I signal peptidase 1, respectively. PolyGly is present within c75 and its deletion or substitution causes mistargeting of Toc75 to the stroma. Here we have examined the properties of polyGly-dependent protein targeting using two soluble passenger proteins, the mature portion of the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (mSS) and enhanced green fluorescent protein (EGFP). Both t75-mSS and t75-EGFP were imported into isolated chloroplasts and their n75 removed. Resultant c75-mSS was associated with the envelope at the intermembrane space, whereas c75-EGFP was partially exposed outside the envelope. Deletion of polyGly or substitution of tri-Ala for the critical tri-Gly segment within polyGly caused each passenger to be targeted to the stroma. Transient expression of t75-EGFP in Nicotiana benthamiana resulted in accumulation of c75-EGFP exposed at the surface of the chloroplast, but the majority of the EGFP passenger was found free in the cytosol with most of its c75 attachment removed. Results of circular dichroism analyses suggest that polyGly within c75 may form an extended conformation, which is disrupted by tri-Ala substitution. These data suggest that polyGly is distinct from a canonical stop-transfer sequence and acts as a rejection signal at the chloroplast inner envelope.
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Affiliation(s)
- Joshua K. Endow
- Department of Plant Sciences, University of California at Davis, One Shields Avenue, Davis, California, United States of America
| | - Agostinho Gomes Rocha
- Department of Plant Sciences, University of California at Davis, One Shields Avenue, Davis, California, United States of America
| | - Amy J. Baldwin
- Department of Plant Sciences, University of California at Davis, One Shields Avenue, Davis, California, United States of America
| | - Rebecca L. Roston
- Department of Plant Sciences, University of California at Davis, One Shields Avenue, Davis, California, United States of America
| | - Toshio Yamaguchi
- Department of Plant Sciences, University of California at Davis, One Shields Avenue, Davis, California, United States of America
| | - Hironari Kamikubo
- Graduate School of Materials Science, Nara Institute of Science and Technology, Takayama, Ikoma, Nara, Japan
| | - Kentaro Inoue
- Department of Plant Sciences, University of California at Davis, One Shields Avenue, Davis, California, United States of America
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Rodríguez-Mejía JL, Roldán-Salgado A, Osuna J, Merino E, Gaytán P. A Codon Deletion at the Beginning of Green Fluorescent Protein Genes Enhances Protein Expression. J Mol Microbiol Biotechnol 2016; 27:1-10. [PMID: 27820932 DOI: 10.1159/000448786] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Recombinant protein expression is one of the key issues in protein engineering and biotechnology. Among the different models for assessing protein production and structure-function studies, green fluorescent protein (GFP) is one of the preferred models because of its importance as a reporter in cellular and molecular studies. In this research we analyze the effect of codon deletions near the amino terminus of different GFP proteins on fluorescence. Our study includes Gly4 deletions in the enhanced GFP (EGFP), the red-shifted GFP and the red-shifted EGFP. The Gly4 deletion mutants and their corresponding wild-type counterparts were transcribed under the control of the T7 or Trc promoters and their expression patterns were analyzed. Different fluorescent outcomes were observed depending on the type of fluorescent gene versions. In silico analysis of the RNA secondary structures near the ribosome binding site revealed a direct relationship between their minimum free energy and GFP production. Integrative analysis of these results, including SDS-PAGE analysis, led us to conclude that the fluorescence improvement of cells expressing different versions of GFPs with Gly4 deleted is due to an enhancement of the accessibility of the ribosome binding site by reducing the stability of the RNA secondary structures at their mRNA leader regions.
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27
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Worst EG, Exner MP, De Simone A, Schenkelberger M, Noireaux V, Budisa N, Ott A. Residue-specific Incorporation of Noncanonical Amino Acids into Model Proteins Using an Escherichia coli Cell-free Transcription-translation System. J Vis Exp 2016. [PMID: 27500416 PMCID: PMC5091720 DOI: 10.3791/54273] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
The canonical set of amino acids leads to an exceptionally wide range of protein functionality. Nevertheless, the set of residues still imposes limitations on potential protein applications. The incorporation of noncanonical amino acids can enlarge this scope. There are two complementary approaches for the incorporation of noncanonical amino acids. For site-specific incorporation, in addition to the endogenous canonical translational machineries, an orthogonal aminoacyl-tRNA-synthetase-tRNA pair must be provided that does not interact with the canonical ones. Consequently, a codon that is not assigned to a canonical amino acid, usually a stop codon, is also required. This genetic code expansion enables the incorporation of a noncanonical amino acid at a single, given site within the protein. The here presented work describes residue-specific incorporation where the genetic code is reassigned within the endogenous translational system. The translation machinery accepts the noncanonical amino acid as a surrogate to incorporate it at canonically prescribed locations, i.e., all occurrences of a canonical amino acid in the protein are replaced by the noncanonical one. The incorporation of noncanonical amino acids can change the protein structure, causing considerably modified physical and chemical properties. Noncanonical amino acid analogs often act as cell growth inhibitors for expression hosts since they modify endogenous proteins, limiting in vivo protein production. In vivo incorporation of toxic noncanonical amino acids into proteins remains particularly challenging. Here, a cell-free approach for a complete replacement of L-arginine by the noncanonical amino acid L-canavanine is presented. It circumvents the inherent difficulties of in vivo expression. Additionally, a protocol to prepare target proteins for mass spectral analysis is included. It is shown that L-lysine can be replaced by L-hydroxy-lysine, albeit with lower efficiency. In principle, any noncanonical amino acid analog can be incorporated using the presented method as long as the endogenous in vitro translation system recognizes it.
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Affiliation(s)
| | | | | | | | | | | | - Albrecht Ott
- Department of Experimental Physics, Saarland University;
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28
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Zaglia T, Di Bona A, Chioato T, Basso C, Ausoni S, Mongillo M. Optimized protocol for immunostaining of experimental GFP-expressing and human hearts. Histochem Cell Biol 2016; 146:407-19. [PMID: 27311322 DOI: 10.1007/s00418-016-1456-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2016] [Indexed: 02/07/2023]
Abstract
Morphological and histochemical analysis of the heart is fundamental for the understanding of cardiac physiology and pathology. The accurate detection of different myocardial cell populations, as well as the high-resolution imaging of protein expression and distribution, within the diverse intracellular compartments, is essential for basic research on disease mechanisms and for the translatability of the results to human pathophysiology. While enormous progress has been made on the imaging hardware and methods and on biotechnological tools [e.g., use of green fluorescent protein (GFP), viral-mediated gene transduction] to investigate heart cell structure and function, most of the protocols to prepare heart tissue samples for analysis have remained almost identical for decades. We here provide a detailed description of a novel protocol of heart processing, tailored to the simultaneous detection of tissue morphology, immunofluorescence markers and native emission of fluorescent proteins (i.e., GFP). We compared a variety of procedures of fixation, antigen unmasking and tissue permeabilization, to identify the best combination for preservation of myocardial morphology and native GFP fluorescence, while simultaneously allowing detection of antibody staining toward sarcomeric, membrane, cytosolic and nuclear markers. Furthermore, with minimal variations, we implemented such protocol for the study of human heart samples, including those already fixed and stored with conventional procedures, in tissue archives or bio-banks. In conclusion, a procedure is here presented for the laboratory investigation of the heart, in both rodents and humans, which accrues from the same tissue section information that would normally require the time-consuming and tissue-wasting observation of multiple serial sections.
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Affiliation(s)
- Tania Zaglia
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/b, 35133, Padua, Italy. .,Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129, Padua, Italy.
| | - Anna Di Bona
- Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129, Padua, Italy.,Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Via A. Gabelli, 61, 35121, Padua, Italy
| | | | - Cristina Basso
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padua, Via A. Gabelli, 61, 35121, Padua, Italy
| | - Simonetta Ausoni
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/b, 35133, Padua, Italy
| | - Marco Mongillo
- Department of Biomedical Sciences, University of Padova, Via Ugo Bassi 58/b, 35133, Padua, Italy.,Venetian Institute of Molecular Medicine (VIMM), Via Orus 2, 35129, Padua, Italy.,CNR Institute of Neuroscience, Viale G. Colombo 3, 35121, Padua, Italy
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Lassalle MW, Kondou S. Uncovering the role of the flexible C-terminal tail: A model study with Strep-tagged GFP. BIOCHIMIE OPEN 2016; 2:1-8. [PMID: 29632832 PMCID: PMC5889473 DOI: 10.1016/j.biopen.2015.11.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 11/18/2015] [Indexed: 11/28/2022]
Abstract
Recently, it has been recognized that, much like an electric current in an electric circuit, dynamic disruptions from flexible, unstructured regions distal to the active region are transferred through the contact network to the active site and influence protein stability and/or function. As transmembrane proteins frequently possess the β-barrel structure, studies of proteins with this topology are required. The unstructured lid segments of the β-barrel GFP protein are conserved and could play a role in the backbone stabilization required for chromophore function. A study of the disordered C-terminus and the function within the lid is necessary. In this study, we entirely truncated the flexible C-terminal tail and investigated the N-terminal Strep-tagged GFP by fluorescence spectroscopy, and the temperature- and GdnHCl-induced unfolding by circular dichroism. The introduction of the unstructured Strep-tag itself changed the unfolding pathway. Truncating the entire flexible tail did not decrease the fluorescence intensity to a large extent; however, the protein stability changed dramatically. The temperature for half-denaturation T1/2 changed significantly from 79 °C for the wild-type to 72.8 °C for the mutant. Unfolding kinetics at different temperatures have been induced by 4 M GdnHCl, and the apparent Arrhenius activation energy decreased by 40% as compared to the wild-type.
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Affiliation(s)
- Michael W. Lassalle
- iCLA (International College of Liberal Arts), Yamanashi Gakuin University, 2-4-5 Sakaori, Kofu-city, Yamanashi-ken, 400-8575 Japan
| | - Shinobu Kondou
- Ehime Prefectural Police HQ, Forensic Science Laboratory, Japan
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30
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Liu SS, Wei X, Ji Q, Xin X, Jiang B, Liu J. A facile and efficient transposon mutagenesis method for generation of multi-codon deletions in protein sequences. J Biotechnol 2016; 227:27-34. [DOI: 10.1016/j.jbiotec.2016.03.038] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 03/17/2016] [Accepted: 03/21/2016] [Indexed: 12/17/2022]
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31
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Wei Z, Xu Z, Liu X, Lo WS, Ye F, Lau CF, Wang F, Zhou JJ, Nangle LA, Yang XL, Zhang M, Schimmel P. Alternative splicing creates two new architectures for human tyrosyl-tRNA synthetase. Nucleic Acids Res 2016; 44:1247-55. [PMID: 26773056 PMCID: PMC4756856 DOI: 10.1093/nar/gkw002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 01/03/2016] [Indexed: 11/15/2022] Open
Abstract
Many human tRNA synthetases evolved alternative functions outside of protein synthesis. These functions are associated with over 200 splice variants (SVs), most of which are catalytic nulls that engender new biology. While known to regulate non-translational activities, little is known about structures resulting from natural internal ablations of any protein. Here, we report analysis of two closely related, internally deleted, SVs of homodimeric human tyrosyl-tRNA synthetase (TyrRS). In spite of both variants ablating a portion of the catalytic core and dimer-interface contacts of native TyrRS, each folded into a distinct stable structure. Biochemical and nuclear magnetic resonance (NMR) analysis showed that the internal deletion of TyrRSΔE2–4 SV gave an alternative, neomorphic dimer interface ‘orthogonal’ to that of native TyrRS. In contrast, the internal C-terminal splice site of TyrRSΔE2–3 prevented either dimerization interface from forming, and yielded a predominantly monomeric protein. Unlike ubiquitous TyrRS, the neomorphs showed clear tissue preferences, which were distinct from each other. The results demonstrate a sophisticated structural plasticity of a human tRNA synthetase for architectural reorganizations that are preferentially elicited in specific tissues.
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Affiliation(s)
- Zhiyi Wei
- IAS HKUST - Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Departmentof Biology, South University of Science and Technology of China, Shenzhen, Guangdong 518055, China
| | - Zhiwen Xu
- IAS HKUST - Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Pangu Biopharma, Edinburgh Tower, The landmark, 15 Queen'sRoad Central, Hong Kong, China
| | - Xiaotian Liu
- Division of Life Science, State Key Laboratory of Molecular Neuroscience Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Wing-Sze Lo
- IAS HKUST - Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Pangu Biopharma, Edinburgh Tower, The landmark, 15 Queen'sRoad Central, Hong Kong, China
| | - Fei Ye
- Division of Life Science, State Key Laboratory of Molecular Neuroscience Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Ching-Fun Lau
- IAS HKUST - Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Pangu Biopharma, Edinburgh Tower, The landmark, 15 Queen'sRoad Central, Hong Kong, China
| | - Feng Wang
- IAS HKUST - Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Pangu Biopharma, Edinburgh Tower, The landmark, 15 Queen'sRoad Central, Hong Kong, China
| | - Jie J Zhou
- IAS HKUST - Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Pangu Biopharma, Edinburgh Tower, The landmark, 15 Queen'sRoad Central, Hong Kong, China
| | - Leslie A Nangle
- aTyr Pharma, 3545 John Hopkins Court, Suite 250, San Diego, CA 92121, USA
| | - Xiang-Lei Yang
- IAS HKUST - Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China The Scripps Laboratories for tRNA Synthetase Research and the Departments of Chemical Physiology and of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Mingjie Zhang
- IAS HKUST - Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Division of Life Science, State Key Laboratory of Molecular Neuroscience Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Paul Schimmel
- IAS HKUST - Scripps R&D Laboratory, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China The Scripps Laboratories for tRNA Synthetase Research and the Departments of Cell and Molecular Biology, and Chemistry, The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA The Scripps Laboratories for tRNA Synthetase Research and Departments of Metabolism & Aging, The Scripps Research Institute, Jupiter, FL 33458, USA
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32
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Liu SS, Wei X, Dong X, Xu L, Liu J, Jiang B. Structural plasticity of green fluorescent protein to amino acid deletions and fluorescence rescue by folding-enhancing mutations. BMC BIOCHEMISTRY 2015. [PMID: 26206151 PMCID: PMC4513630 DOI: 10.1186/s12858-015-0046-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND Green fluorescent protein (GFP) and its derivative fluorescent proteins (FPs) are among the most commonly used reporter systems for studying gene expression and protein interaction in biomedical research. Most commercially available FPs have been optimized for their oligomerization state to prevent potential structural constraints that may interfere with the native function of fused proteins. Other approach to reducing structural constraints may include minimizing the structure of GFPs. Previous studies in an enhanced GFP variant (EGFP) identified a series of deletions that can retain GFP fluorescence. In this study, we interrogated the structural plasticity of a UV-optimized GFP variant (GFP(UV)) to amino acid deletions, characterized the effects of deletions and explored the feasibility of rescuing the fluorescence of deletion mutants using folding-enhancing mutations. METHODS Transposon mutagenesis was used to screen amino acid deletions in GFP that led to fluorescent and nonfluorescent phenotypes. The fluorescent GFP mutants were characterized for their whole-cell fluorescence and fraction soluble. Fluorescent GFP mutants with internal deletions were purified and characterized for their spectral and folding properties. Folding-ehancing mutations were introduced to deletion mutants to rescue their compromised fluorescence. RESULTS We identified twelve amino acid deletions that can retain the fluorescence of GFP(UV). Seven of these deletions are either at the N- or C- terminus, while the other five are located at internal helices or strands. Further analysis suggested that the five internal deletions diminished the efficiency of protein folding and chromophore maturation. Protein expression under hypothermic condition or incorporation of folding-enhancing mutations could rescue the compromised fluorescence of deletion mutants. In addition, we generated dual deletion mutants that can retain GFP fluorescence. CONCLUSION Our results suggested that a "size-minimized" GFP may be developed by iterative incorporation of amino acid deletions, followed by fluorescence rescue with folding-enhancing mutations.
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Affiliation(s)
- Shu-su Liu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
| | - Xuan Wei
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
| | - Xue Dong
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
| | - Liang Xu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
| | - Jia Liu
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China. .,Department of Chemistry and Biochemistry, University of Maryland, College Park, USA.
| | - Biao Jiang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China.
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Chishti AA, Hellweg CE, Berger T, Baumstark-Khan C, Feles S, Kätzel T, Reitz G. Constitutive expression of tdTomato protein as a cytotoxicity and proliferation marker for space radiation biology. LIFE SCIENCES IN SPACE RESEARCH 2015; 4:35-45. [PMID: 26177619 DOI: 10.1016/j.lssr.2014.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 12/21/2014] [Accepted: 12/30/2014] [Indexed: 06/04/2023]
Abstract
The radiation risk assessment for long-term space missions requires knowledge on the biological effectiveness of different space radiation components, e.g. heavy ions, on the interaction of radiation and other space environmental factors such as microgravity, and on the physical and biological dose distribution in the human body. Space experiments and ground-based experiments at heavy ion accelerators require fast and reliable test systems with an easy readout for different endpoints. In order to determine the effect of different radiation qualities on cellular proliferation and the biological depth dose distribution after heavy ion exposure, a stable human cell line expressing a novel fluorescent protein was established and characterized. tdTomato, a red fluorescent protein of the new generation with fast maturation and high fluorescence intensity, was selected as reporter of cell proliferation. Human embryonic kidney (HEK/293) cells were stably transfected with a plasmid encoding tdTomato under the control of the constitutively active cytomegalovirus (CMV) promoter (ptdTomato-N1). The stably transfected cell line was named HEK-ptdTomato-N1 8. This cytotoxicity biosensor was tested by ionizing radiation (X-rays and accelerated heavy ions) exposure. As biological endpoints, the proliferation kinetics and the cell density reached 100 h after irradiation reflected by constitutive expression of the tdTomato were investigated. Both were reduced dose-dependently after radiation exposure. Finally, the cell line was used for biological weighting of heavy ions of different linear energy transfer (LET) as space-relevant radiation quality. The relative biological effectiveness of accelerated heavy ions in reducing cellular proliferation peaked at an LET of 91 keV/μm. The results of this study demonstrate that the HEK-ptdTomato-N1 reporter cell line can be used as a fast and reliable biosensor system for detection of cytotoxic damage caused by ionizing radiation.
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Affiliation(s)
- Arif A Chishti
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology, Linder Höhe, D-51147 Köln, Germany.
| | - Christine E Hellweg
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology, Linder Höhe, D-51147 Köln, Germany.
| | - Thomas Berger
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology, Linder Höhe, D-51147 Köln, Germany.
| | - Christa Baumstark-Khan
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology, Linder Höhe, D-51147 Köln, Germany.
| | - Sebastian Feles
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology, Linder Höhe, D-51147 Köln, Germany.
| | - Thorben Kätzel
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology, Linder Höhe, D-51147 Köln, Germany.
| | - Günther Reitz
- German Aerospace Center (DLR), Institute of Aerospace Medicine, Radiation Biology, Linder Höhe, D-51147 Köln, Germany.
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34
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Han Z, Jin L, Chen F, Loturco JJ, Cohen LB, Bondar A, Lazar J, Pieribone VA. Mechanistic studies of the genetically encoded fluorescent protein voltage probe ArcLight. PLoS One 2014; 9:e113873. [PMID: 25419571 PMCID: PMC4242678 DOI: 10.1371/journal.pone.0113873] [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: 06/13/2014] [Accepted: 10/31/2014] [Indexed: 11/17/2022] Open
Abstract
ArcLight, a genetically encoded fluorescent protein voltage probe with a large ΔF/ΔV, is a fusion between the voltage sensing domain of the Ciona instestinalis voltage sensitive phosphatase and super ecliptic pHluorin carrying a single mutation (A227D in the fluorescent protein). Without this mutation the probe produces only a very small change in fluorescence in response to voltage deflections (∼1%). The large signal afforded by this mutation allows optical detection of action potentials and sub-threshold electrical events in single-trials in vitro and in vivo. However, it is unclear how this single mutation produces a probe with such a large modulation of its fluorescence output with changes in membrane potential. In this study, we identified which residues in super ecliptic pHluorin (vs eGFP) are critical for the ArcLight response, as a similarly constructed probe based on eGFP also exhibits large response amplitude if it carries these critical residues. We found that D147 is responsible for determining the pH sensitivity of the fluorescent protein used in these probes but by itself does not result in a voltage probe with a large signal. We also provide evidence that the voltage dependent signal of ArcLight is not simply sensing environmental pH changes. A two-photon polarization microscopy study showed that ArcLight's response to changes in membrane potential includes a reorientation of the super ecliptic pHluorin. We also explored different changes including modification of linker length, deletion of non-essential amino acids in the super ecliptic pHluorin, adding a farnesylation site, using tandem fluorescent proteins and other pH sensitive fluorescent proteins.
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Affiliation(s)
- Zhou Han
- The John B. Pierce Laboratory, Inc., New Haven, Connecticut, United States of America; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Lei Jin
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Fuyi Chen
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Joseph J Loturco
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, United States of America
| | - Lawrence B Cohen
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, United States of America; Center for Functional Connectomics, Korea Institute of Science and Technology, Seoul, Republic of Korea
| | - Alexey Bondar
- Institute of Nanobiology and Structural Biology GCRC, Academy of Sciences of the Czech Republic, Zamek 136, Nove Hrady, Czech Republic; Department of Molecular Biology, University of South Bohemia, Branisovska 31, Ceske Budejovice, Czech Republic
| | - Josef Lazar
- Institute of Nanobiology and Structural Biology GCRC, Academy of Sciences of the Czech Republic, Zamek 136, Nove Hrady, Czech Republic; Department of Molecular Biology, University of South Bohemia, Branisovska 31, Ceske Budejovice, Czech Republic
| | - Vincent A Pieribone
- The John B. Pierce Laboratory, Inc., New Haven, Connecticut, United States of America; Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut, United States of America; Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut, United States of America
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Gurunathan S, Woong Han J, Kim E, Kwon DN, Park JK, Kim JH. Enhanced green fluorescent protein-mediated synthesis of biocompatible graphene. J Nanobiotechnology 2014; 12:41. [PMID: 25273520 PMCID: PMC4193993 DOI: 10.1186/s12951-014-0041-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 09/26/2014] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Graphene is the 2D form of carbon that exists as a single layer of atoms arranged in a honeycomb lattice and has attracted great interest in the last decade in view of its physical, chemical, electrical, elastic, thermal, and biocompatible properties. The objective of this study was to synthesize an environmentally friendly and simple methodology for the preparation of graphene using a recombinant enhanced green fluorescent protein (EGFP). RESULTS The successful reduction of GO to graphene was confirmed using UV-vis spectroscopy, and FT-IR. DLS and SEM were employed to demonstrate the particle size and surface morphology of GO and EGFP-rGO. The results from Raman spectroscopy suggest the removal of oxygen-containing functional groups from the surface of GO and formation of graphene with defects. The biocompatibility analysis of GO and EGFP-rGO in human embryonic kidney (HEK) 293 cells suggests that GO induces significant concentration-dependent cell toxicity in HEK cells, whereas graphene exerts no adverse effects on HEK cells even at a higher concentration (100 μg/mL). CONCLUSIONS Altogether, our findings suggest that recombinant EGFP can be used as a reducing and stabilizing agent for the preparation of biocompatible graphene. The novelty and originality of this work is that it describes a safe, simple, and environmentally friendly method for the production of graphene using recombinant enhanced green fluorescent protein. Furthermore, the synthesized graphene shows excellent biocompatibility with HEK cells; therefore, biologically synthesized graphene can be used for biomedical applications. To the best of our knowledge, this is the first and novel report describing the synthesis of graphene using recombinant EGFP.
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Affiliation(s)
- Sangiliyandi Gurunathan
- />Department of Animal Biotechnology, Konkuk University, 1 Hwayang-Dong, Gwangin-gu Seoul, 143-701 South Korea
- />GS Institute of Bio and Nanotechnology, Coimbatore, Tamil Nadu 641024 India
| | - Jae Woong Han
- />Department of Animal Biotechnology, Konkuk University, 1 Hwayang-Dong, Gwangin-gu Seoul, 143-701 South Korea
| | - Eunsu Kim
- />Department of Animal Biotechnology, Konkuk University, 1 Hwayang-Dong, Gwangin-gu Seoul, 143-701 South Korea
| | - Deug-Nam Kwon
- />Department of Animal Biotechnology, Konkuk University, 1 Hwayang-Dong, Gwangin-gu Seoul, 143-701 South Korea
| | - Jin-Ki Park
- />Animal Biotechnology Division, National Institute of Animal Science, Suwon, 441-350 Korea
| | - Jin-Hoi Kim
- />Department of Animal Biotechnology, Konkuk University, 1 Hwayang-Dong, Gwangin-gu Seoul, 143-701 South Korea
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Arpino JAJ, Rizkallah PJ, Jones DD. Structural and dynamic changes associated with beneficial engineered single-amino-acid deletion mutations in enhanced green fluorescent protein. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:2152-62. [PMID: 25084334 PMCID: PMC4118826 DOI: 10.1107/s139900471401267x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 05/31/2014] [Indexed: 01/23/2023]
Abstract
Single-amino-acid deletions are a common part of the natural evolutionary landscape but are rarely sampled during protein engineering owing to limited and prejudiced molecular understanding of mutations that shorten the protein backbone. Single-amino-acid deletion variants of enhanced green fluorescent protein (EGFP) have been identified by directed evolution with the beneficial effect of imparting increased cellular fluorescence. Biophysical characterization revealed that increased functional protein production and not changes to the fluorescence parameters was the mechanism that was likely to be responsible. The structure EGFP(D190Δ) containing a deletion within a loop revealed propagated changes only after the deleted residue. The structure of EGFP(A227Δ) revealed that a `flipping' mechanism was used to adjust for residue deletion at the end of a β-strand, with amino acids C-terminal to the deletion site repositioning to take the place of the deleted amino acid. In both variants new networks of short-range and long-range interactions are generated while maintaining the integrity of the hydrophobic core. Both deletion variants also displayed significant local and long-range changes in dynamics, as evident by changes in B factors compared with EGFP. Rather than being detrimental, deletion mutations can introduce beneficial structural effects through altering core protein properties, folding and dynamics, as well as function.
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Affiliation(s)
- James A. J. Arpino
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AT, Wales
| | | | - D. Dafydd Jones
- School of Biosciences, Cardiff University, Park Place, Cardiff CF10 3AT, Wales
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Arpino JAJ, Reddington SC, Halliwell LM, Rizkallah PJ, Jones DD. Random single amino acid deletion sampling unveils structural tolerance and the benefits of helical registry shift on GFP folding and structure. Structure 2014; 22:889-98. [PMID: 24856363 PMCID: PMC4058518 DOI: 10.1016/j.str.2014.03.014] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 03/08/2014] [Accepted: 03/10/2014] [Indexed: 12/01/2022]
Abstract
Altering a protein’s backbone through amino acid deletion is a common evolutionary mutational mechanism, but is generally ignored during protein engineering primarily because its effect on the folding-structure-function relationship is difficult to predict. Using directed evolution, enhanced green fluorescent protein (EGFP) was observed to tolerate residue deletion across the breadth of the protein, particularly within short and long loops, helical elements, and at the termini of strands. A variant with G4 removed from a helix (EGFPG4Δ) conferred significantly higher cellular fluorescence. Folding analysis revealed that EGFPG4Δ retained more structure upon unfolding and refolded with almost 100% efficiency but at the expense of thermodynamic stability. The EGFPG4Δ structure revealed that G4 deletion caused a beneficial helical registry shift resulting in a new polar interaction network, which potentially stabilizes a cis proline peptide bond and links secondary structure elements. Thus, deletion mutations and registry shifts can enhance proteins through structural rearrangements not possible by substitution mutations alone. Using directed evolution, the impact of amino acid deletion on EGFP is explored Loops, helices, and strand termini are especially tolerant to amino acid deletion A deletion mutant that enhances cellular production and fluorescence is identified Structure reveals that a helical registry shift creates a new polar network
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Affiliation(s)
- James A J Arpino
- School of Biosciences, Main Building, Park Place, Cardiff University, Cardiff CF10 3AT, UK
| | - Samuel C Reddington
- School of Biosciences, Main Building, Park Place, Cardiff University, Cardiff CF10 3AT, UK
| | - Lisa M Halliwell
- School of Biosciences, Main Building, Park Place, Cardiff University, Cardiff CF10 3AT, UK
| | - Pierre J Rizkallah
- School of Medicine, Cardiff University, WHRI, Main Building, Heath Park, Cardiff CF14 4XN, UK
| | - D Dafydd Jones
- School of Biosciences, Main Building, Park Place, Cardiff University, Cardiff CF10 3AT, UK.
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Wu P, Nicholls S, Hardy J. A tunable, modular approach to fluorescent protease-activated reporters. Biophys J 2013; 104:1605-14. [PMID: 23561537 PMCID: PMC3617415 DOI: 10.1016/j.bpj.2013.01.058] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 01/04/2013] [Accepted: 01/29/2013] [Indexed: 11/26/2022] Open
Abstract
Proteases are one of the most important and historically utilized classes of drug targets. To effectively interrogate this class of proteins, which encodes nearly 2% of the human proteome, it is necessary to develop effective and cost-efficient methods that report on their activity both in vitro and in vivo. We have developed a robust reporter of caspase proteolytic activity, called caspase-activatable green fluorescent protein (CA-GFP). The caspases play central roles in homeostatic regulation, as they execute programmed cell death, and in drug design, as caspases are involved in diseases ranging from cancer to neurodegeneration. CA-GFP is a genetically encoded dark-to-bright fluorescent reporter of caspase activity in in vitro, cell-based, and animal systems. Based on the CA-GFP platform, we developed reporters that can discriminate the activities of caspase-6 and -7, two highly related proteases. A second series of reporters, activated by human rhinovirus 3C protease, demonstrated that we could alter the specificity of the reporter by reengineering the protease recognition sequence. Finally, we took advantage of the spectrum of known fluorescent proteins to generate green, yellow, cyan, and red reporters, paving the way for multiplex protease monitoring.
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Affiliation(s)
| | | | - Jeanne A. Hardy
- Department of Chemistry, University of Massachusetts Amherst, Amherst, Massachusetts
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Role of recombinant plasmid pEGFP-N1-IGF-1 transfection in alleviating osteoporosis in ovariectomized rats. J Mol Histol 2013; 44:535-44. [PMID: 23508541 DOI: 10.1007/s10735-013-9498-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 03/11/2013] [Indexed: 01/13/2023]
Abstract
Decreased levels of serum insulin-like growth factor-1 (IGF-1) have been proven to cause osteoporosis. Gene transfer of IGF-1 offers an attractive technology to treat skeletal metabolic disorders including osteoporosis, but the viral vectors are limited by their high antigenicity and immune response. Our purpose was to investigate the expression of a non-invasive vector, recombinant plasmid enhanced green fluorescent protein-N1 (pEGFP-N1) that transferred IGF-1 gene into ovariectomized (OVX) rats in vivo and evaluate the effect of this therapy on osteoporosis. OVX or sham operations were performed in 60 female, 7-month-old unmated SD rats. 12 weeks after OVX operation, the vectors were transfected to the 10-month-old rats and experimental data were detected from 48 h to 7 week after transfection. Our results showed that remarkable expression of fluorescence and serum IGF-1 was observed in the rats transfected by recombinant plasmids, indicating that IGF-1 gene was successfully transferred to OVX rats by injecting the vector through hydrodynamic method via the tail vein. The bone metabolism index including serum alkaline phosphatase, the histomorphometric parameters of lumbar vertebra including trabecular area percentage, trabecular thickness, trabecular number and trabecular separation, and the bone mineral density (BMD) and biomechanical parameters of lumbar vertebra including BMD, maximum condensing force, crushing strength in OVX rats transfected by pEGFP-N1-IGF-1 were improved remarkably compared with OVX+pEGFP-N1 rats, indicating that the transfection of recombinant plasmid pEGFP-N1-IGF-1 played a significant role in alleviating osteoporosis in rats induced by OVX. This encouraged a potential approach of IGF-1 gene therapy to the treatment of osteoporosis.
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40
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Raghunathan G, Soundrarajan N, Sokalingam S, Yun H, Lee SG. Deletional protein engineering based on stable fold. PLoS One 2012; 7:e51510. [PMID: 23240034 PMCID: PMC3519881 DOI: 10.1371/journal.pone.0051510] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2012] [Accepted: 11/01/2012] [Indexed: 12/14/2022] Open
Abstract
Diversification of protein sequence-structure space is a major concern in protein engineering. Deletion mutagenesis can generate a protein sequence-structure space different from substitution mutagenesis mediated space, but it has not been widely used in protein engineering compared to substitution mutagenesis, because it causes a relatively huge range of structural perturbations of target proteins which often inactivates the proteins. In this study, we demonstrate that, using green fluorescent protein (GFP) as a model system, the drawback of the deletional protein engineering can be overcome by employing the protein structure with high stability. The systematic dissection of N-terminal, C-terminal and internal sequences of GFPs with two different stabilities showed that GFP with high stability (s-GFP), was more tolerant to the elimination of amino acids compared to a GFP with normal stability (n-GFP). The deletion studies of s-GFP enabled us to achieve three interesting variants viz. s-DL4, s-N14, and s-C225, which could not been obtained from n-GFP. The deletion of 191–196 loop sequences led to the variant s-DL4 that was expressed predominantly as insoluble form but mostly active. The s-N14 and s-C225 are the variants without the amino acid residues involving secondary structures around N- and C-terminals of GFP fold respectively, exhibiting comparable biophysical properties of the n-GFP. Structural analysis of the variants through computational modeling study gave a few structural insights that can explain the spectral properties of the variants. Our study suggests that the protein sequence-structure space of deletion mutants can be more efficiently explored by employing the protein structure with higher stability.
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Affiliation(s)
- Govindan Raghunathan
- Department of Chemical Engineering, Pusan National University, Busan, South Korea
| | | | - Sriram Sokalingam
- Department of Chemical Engineering, Pusan National University, Busan, South Korea
| | - Hyungdon Yun
- School of Biotechnology, Yeungnam University, Gyeongsan, South Korea
| | - Sun-Gu Lee
- Department of Chemical Engineering, Pusan National University, Busan, South Korea
- * E-mail:
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Saeger J, Hytönen VP, Klotzsch E, Vogel V. GFP's mechanical intermediate states. PLoS One 2012; 7:e46962. [PMID: 23118864 PMCID: PMC3485268 DOI: 10.1371/journal.pone.0046962] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 09/07/2012] [Indexed: 11/19/2022] Open
Abstract
Green fluorescent protein (GFP) mutants have become the most widely used fluorescence markers in the life sciences, and although they are becoming increasingly popular as mechanical force or strain probes, there is little direct information on how their fluorescence changes when mechanically stretched. Here we derive high-resolution structural models of the mechanical intermediate states of stretched GFP using steered molecular dynamics (SMD) simulations. These structures were used to produce mutants of EGFP and EYFP that mimic GFP's different mechanical intermediates. A spectroscopic analysis revealed that a population of EGFP molecules with a missing N-terminal α-helix was significantly dimmed, while the fluorescence lifetime characteristic of the anionic chromophore state remained unaffected. This suggests a mechanism how N-terminal deletions can switch the protonation state of the chromophore, and how the fluorescence of GFP molecules in response to mechanical disturbance might be turned off.
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Affiliation(s)
- John Saeger
- Laboratory of Applied Mechanobiology, Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
| | - Vesa P. Hytönen
- Laboratory of Applied Mechanobiology, Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
- Institute of Biomedical Technology, University of Tampere and Tampere University Hospital, Tampere, Finland
| | - Enrico Klotzsch
- Laboratory of Applied Mechanobiology, Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
| | - Viola Vogel
- Laboratory of Applied Mechanobiology, Department of Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
- * E-mail:
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42
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Vorobjev IA, Buchholz K, Prabhat P, Ketman K, Egan ES, Marti M, Duraisingh MT, Barteneva NS. Optimization of flow cytometric detection and cell sorting of transgenic Plasmodium parasites using interchangeable optical filters. Malar J 2012; 11:312. [PMID: 22950515 PMCID: PMC3544587 DOI: 10.1186/1475-2875-11-312] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Accepted: 08/29/2012] [Indexed: 12/05/2022] Open
Abstract
Background Malaria remains a major cause of morbidity and mortality worldwide. Flow cytometry-based assays that take advantage of fluorescent protein (FP)-expressing malaria parasites have proven to be valuable tools for quantification and sorting of specific subpopulations of parasite-infected red blood cells. However, identification of rare subpopulations of parasites using green fluorescent protein (GFP) labelling is complicated by autofluorescence (AF) of red blood cells and low signal from transgenic parasites. It has been suggested that cell sorting yield could be improved by using filters that precisely match the emission spectrum of GFP. Methods Detection of transgenic Plasmodium falciparum parasites expressing either tdTomato or GFP was performed using a flow cytometer with interchangeable optical filters. Parasitaemia was evaluated using different optical filters and, after optimization of optics, the GFP-expressing parasites were sorted and analysed by microscopy after cytospin preparation and by imaging cytometry. Results A new approach to evaluate filter performance in flow cytometry using two-dimensional dot blot was developed. By selecting optical filters with narrow bandpass (BP) and maximum position of filter emission close to GFP maximum emission in the FL1 channel (510/20, 512/20 and 517/20; dichroics 502LP and 466LP), AF was markedly decreased and signal-background improve dramatically. Sorting of GFP-expressing parasite populations in infected red blood cells at 90 or 95% purity with these filters resulted in 50-150% increased yield when compared to the standard filter set-up. The purity of the sorted population was confirmed using imaging cytometry and microscopy of cytospin preparations of sorted red blood cells infected with transgenic malaria parasites. Discussion Filter optimization is particularly important for applications where the FP signal and percentage of positive events are relatively low, such as analysis of parasite-infected samples with in the intention of gene-expression profiling and analysis. The approach outlined here results in substantially improved yield of GFP-expressing parasites, and requires decreased sorting time in comparison to standard methods. It is anticipated that this protocol will be useful for a wide range of applications involving rare events.
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Affiliation(s)
- Ivan A Vorobjev
- Immune Disease Institute and Program in Cellular and Molecular Medicine, Children's Hospital, D-239, 200 Longwood Avenue, 02115, Boston, MA, USA
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Kara RJ, Bolli P, Matsunaga I, Tanweer O, Altman P, Chaudhry HW. A mouse model for fetal maternal stem cell transfer during ischemic cardiac injury. Clin Transl Sci 2012; 5:321-8. [PMID: 22883609 DOI: 10.1111/j.1752-8062.2012.00424.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Fetal cells enter the maternal circulation during pregnancies and can persist in blood and tissues for decades, creating a state of physiologic microchimerism. Microchimerism refers to acquisition of cells from another individual and can be due to bidirectional cell traffic between mother and fetus during pregnancy. Peripartum cardiomyopathy, a rare cardiac disorder associated with high mortality rates has the highest recovery rate amongst all etiologies of heart failure although the reason is unknown. Collectively, these observations led us to hypothesize that fetal cells enter the maternal circulation and may be recruited to the sites of myocardial disease or injury. The ability to genetically modify mice makes them an ideal system for studying the phenomenon of microchimerism in cardiac disease. Described here is a mouse model for ischemic cardiac injury during pregnancy designed to study microchimerism. Wild-type virgin female mice mated with eGFP male mice underwent ligation of the left anterior descending artery to induce a myocardial infarction at gestation day 12. We demonstrate the selective homing of eGFP cells to the site of cardiac injury without such homing to noninjured tissues suggesting the presence of precise signals sensed by fetal cells enabling them to target diseased myocardium specifically.
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Affiliation(s)
- Rina J Kara
- Mount Sinai School of Medicine, Cardiovascular Institute, New York, New York, USA
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44
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Hunt J, Keeble AH, Dale RE, Corbett MK, Beavil RL, Levitt J, Swann MJ, Suhling K, Ameer-Beg S, Sutton BJ, Beavil AJ. A fluorescent biosensor reveals conformational changes in human immunoglobulin E Fc: implications for mechanisms of receptor binding, inhibition, and allergen recognition. J Biol Chem 2012; 287:17459-17470. [PMID: 22442150 PMCID: PMC3366799 DOI: 10.1074/jbc.m111.331967] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 03/08/2012] [Indexed: 11/06/2022] Open
Abstract
IgE binding to its high affinity receptor FcεRI on mast cells and basophils is a key step in the mechanism of allergic disease and a target for therapeutic intervention. Early indications that IgE adopts a bent structure in solution have been confirmed by recent x-ray crystallographic studies of IgEFc, which further showed that the bend, contrary to expectation, is enhanced in the crystal structure of the complex with receptor. To investigate the structure of IgEFc and its conformational changes that accompany receptor binding in solution, we created a Förster resonance energy transfer (FRET) biosensor using biologically encoded fluorescent proteins fused to the N- and C-terminal IgEFc domains (Cε2 and Cε4, respectively) together with the theoretical basis for quantitating its behavior. This revealed not only that the IgEFc exists in a bent conformation in solution but also that the bend is indeed enhanced upon FcεRI binding. No change in the degree of bending was seen upon binding to the B cell receptor for IgE, CD23 (FcεRII), but in contrast, binding of the anti-IgE therapeutic antibody omalizumab decreases the extent of the bend, implying a conformational change that opposes FcεRI engagement. HomoFRET measurements further revealed that the (Cε2)(2) and (Cε4)(2) domain pairs behave as rigid units flanking the conformational change in the Cε3 domains. Finally, modeling of the accessible conformations of the two Fab arms in FcεRI-bound IgE revealed a mutual exclusion not seen in IgG and Fab orientations relative to the membrane that may predispose receptor-bound IgE to cross-linking by allergens.
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Affiliation(s)
- James Hunt
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, Guy's Hospital Campus, London SE1 1UL; The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL; The Division of Asthma Allergy and Lung Biology, King's College London, Guy's Hospital Campus, London SE1 1UL
| | - Anthony H Keeble
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, Guy's Hospital Campus, London SE1 1UL; The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL; The Division of Asthma Allergy and Lung Biology, King's College London, Guy's Hospital Campus, London SE1 1UL
| | - Robert E Dale
- The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL
| | - Melissa K Corbett
- The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL
| | - Rebecca L Beavil
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, Guy's Hospital Campus, London SE1 1UL; The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL; The Division of Asthma Allergy and Lung Biology, King's College London, Guy's Hospital Campus, London SE1 1UL
| | - James Levitt
- The Department of Physics, King's College London, Strand, London WC2R 2LS
| | - Marcus J Swann
- Farfield Group Limited, Voyager, Chicago Avenue, Manchester Airport, Manchester, M90 3DQ, United Kingdom
| | - Klaus Suhling
- The Department of Physics, King's College London, Strand, London WC2R 2LS
| | - Simon Ameer-Beg
- The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL
| | - Brian J Sutton
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, Guy's Hospital Campus, London SE1 1UL; The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL
| | - Andrew J Beavil
- MRC and Asthma UK Centre in Allergic Mechanisms of Asthma, Guy's Hospital Campus, London SE1 1UL; The Randall Division of Cell and Molecular Biophysics, Guy's Hospital Campus, London SE1 1UL; The Division of Asthma Allergy and Lung Biology, King's College London, Guy's Hospital Campus, London SE1 1UL.
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Kelkar DA, Khushoo A, Yang Z, Skach WR. Kinetic analysis of ribosome-bound fluorescent proteins reveals an early, stable, cotranslational folding intermediate. J Biol Chem 2011; 287:2568-78. [PMID: 22128180 DOI: 10.1074/jbc.m111.318766] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Protein folding in cells reflects a delicate interplay between biophysical properties of the nascent polypeptide, the vectorial nature and rate of translation, molecular crowding, and cellular biosynthetic machinery. To better understand how this complex environment affects de novo folding pathways as they occur in the cell, we expressed β-barrel fluorescent proteins derived from GFP and RFP in an in vitro system that allows direct analysis of cotranslational folding intermediates. Quantitative analysis of ribosome-bound eCFP and mCherry fusion proteins revealed that productive folding exhibits a sharp threshold as the length of polypeptide from the C terminus to the ribosome peptidyltransferase center is increased. Fluorescence spectroscopy, urea denaturation, and limited protease digestion confirmed that sequestration of only 10-15 C-terminal residues within the ribosome exit tunnel effectively prevents stable barrel formation, whereas folding occurs unimpeded when the C terminus is extended beyond the ribosome exit site. Nascent FPs with 10 of the 11 β-strands outside the ribosome exit tunnel acquire a non-native conformation that is remarkably stable in diverse environments. Upon ribosome release, these structural intermediates fold efficiently with kinetics that are unaffected by the cytosolic crowding or cellular chaperones. Our results indicate that during synthesis, fluorescent protein folding is initiated cotranslationally via rapid formation of a highly stable, on-pathway structural intermediate and that the rate-limiting step of folding involves autonomous incorporation of the 11th β-strand into the mature barrel structure.
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Affiliation(s)
- Devaki A Kelkar
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, Oregon 97239, USA
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Caraglio M, Imparato A, Pelizzola A. Direction-dependent mechanical unfolding and green fluorescent protein as a force sensor. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:021918. [PMID: 21929030 DOI: 10.1103/physreve.84.021918] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 07/05/2011] [Indexed: 05/31/2023]
Abstract
An Ising-like model of proteins is used to investigate the mechanical unfolding of the green fluorescent protein along different directions. When the protein is pulled from its ends, we recover the major and minor unfolding pathways observed in experiments. Upon varying the pulling direction, we find the correct order of magnitude and ranking of the unfolding forces. Exploiting the direction dependence of the unfolding force at equilibrium, we propose a force sensor whose luminescence depends on the applied force.
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Affiliation(s)
- M Caraglio
- Dipartimento di Fisica and CNISM, Politecnico di Torino, c. Duca degli Abruzzi 24, Torino, Italy.
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Harting MT, Jimenez F, Cox CS. Isolation of mesenchymal stem cells (MSCs) from green fluorescent protein positive (GFP+) transgenic rodents: the grass is not always green(er). Stem Cells Dev 2010; 18:127-35. [PMID: 18518666 DOI: 10.1089/scd.2008.0046] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Cellular therapy is under intense basic science and clinical investigation as a therapeutic intervention. One of the challenges lies in tracking these cells in vivo. While there are many ways to label and track cells--each with strengths and weaknesses--the green fluorescent protein (GFP) is a reporter gene commonly employed. We report a significant and consistent reduction in the expression of GFP with the culture of mesenchymal stem cells (MSCs) isolated from the bone marrow of GFP(+) transgenic rodents. After MSC isolation and immunophenotype characterization, along with co-localization with GFP, MSCs were evaluated for GFP expression through flow cytometry and fluorescent microscopy, revealing that only 50% of the cells expressed GFP. Differentiation of the cells to adipocytes did not alter the GFP expression significantly. Incubation with an anti-GFP antibody increased the fluorescent intensity of the GFP-expressing and some of the GFP nonexpressing cells. Incubation of MSCs with a histone deacetylase inhibitor, trichostatin A, did not significantly alter GFP expression, while incubation with a DNA demethylation reagent, 5-azacytidine, increased GFP expression, suggesting that epigenetic modification by DNA methylation may play a role in GFP expression among MSCs.
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Affiliation(s)
- Matthew T Harting
- Department of Pediatric Surgery and Trauma Research Center, University of Texas Medical School, Houston, Texas 77030, USA
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Ugrinov KG, Clark PL. Cotranslational folding increases GFP folding yield. Biophys J 2010; 98:1312-20. [PMID: 20371331 DOI: 10.1016/j.bpj.2009.12.4291] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Revised: 10/31/2009] [Accepted: 12/04/2009] [Indexed: 10/19/2022] Open
Abstract
Protein sequences evolved to fold in cells, including cotranslational folding of nascent polypeptide chains during their synthesis by the ribosome. The vectorial (N- to C-terminal) nature of cotranslational folding constrains the conformations of the nascent polypeptide chain in a manner not experienced by full-length chains diluted out of denaturant. We are still discovering to what extent these constraints affect later, posttranslational folding events. Here we directly address whether conformational constraints imposed by cotranslational folding affect the partitioning between productive folding to the native structure versus aggregation. We isolated polyribosomes from Escherichia coli cells expressing GFP, analyzed the nascent chain length distribution to determine the number of nascent chains that were long enough to fold to the native fluorescent structure, and calculated the folding yield for these nascent chains upon ribosome release versus the folding yield of an equivalent concentration of full-length, chemically denatured GFP polypeptide chains. We find that the yield of native fluorescent GFP is dramatically higher upon ribosome release of nascent chains versus dilution of full-length chains from denaturant. For kinetically trapped native structures such as GFP, folding correctly the first time, immediately after release from the ribosome, can lead to lifelong population of the native structure, as opposed to aggregation.
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Affiliation(s)
- Krastyu G Ugrinov
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
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Shin J, Noireaux V. Efficient cell-free expression with the endogenous E. Coli RNA polymerase and sigma factor 70. J Biol Eng 2010; 4:8. [PMID: 20576148 PMCID: PMC3161345 DOI: 10.1186/1754-1611-4-8] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Accepted: 06/24/2010] [Indexed: 11/24/2022] Open
Abstract
Background Escherichia coli cell-free expression systems use bacteriophage RNA polymerases, such as T7, to synthesize large amounts of recombinant proteins. These systems are used for many applications in biotechnology, such as proteomics. Recently, informational processes have been reconstituted in vitro with cell-free systems. These synthetic approaches, however, have been seriously limited by a lack of transcription modularity. The current available cell-free systems have been optimized to work with bacteriophage RNA polymerases, which put significant restrictions to engineer processes related to biological information. The development of efficient cell-free systems with broader transcription capabilities is required to study complex informational processes in vitro. Results In this work, an efficient cell-free expression system that uses the endogenous E. coli RNA polymerase only and sigma factor 70 for transcription was prepared. Approximately 0.75 mg/ml of Firefly luciferase and enhanced green fluorescent protein were produced in batch mode. A plasmid was optimized with different regulatory parts to increase the expression. In addition, a new eGFP was engineered that is more translatable in cell-free systems than the original eGFP. The protein production was characterized with three different adenosine triphosphate (ATP) regeneration systems: creatine phosphate (CP), phosphoenolpyruvate (PEP), and 3-phosphoglyceric acid (3-PGA). The maximum protein production was obtained with 3-PGA. Preparation of the crude extract was streamlined to a simple routine procedure that takes 12 hours including cell culture. Conclusions Although it uses the endogenous E. coli transcription machinery, this cell-free system can produce active proteins in quantities comparable to bacteriophage systems. The E. coli transcription provides much more possibilities to engineer informational processes in vitro. Many E. coli promoters/operators specific to sigma factor 70 are available that form a broad library of regulatory parts. In this work, cell-free expression is developed as a toolbox to design and to study synthetic gene circuits in vitro.
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Affiliation(s)
- Jonghyeon Shin
- University of Minnesota, 116 Church Street S,E,, Minneapolis, MN 55455, USA.
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Abstract
Recognition of the AUG start codon on mRNAs during translation initiation in eukaryotes occurs in a preinitiation complex that includes small ribosomal subunits and multiple translation initiation factors. The complexity of this process and the lack of appropriate tools have prevented its genetic study in multicellular organisms. Here we describe a genetic system in the nematode Caenorhabditis elegans to study how the AUG start codon is selected. We have generated a sensitive reporter assay that allows for the isolation of mutants with reduced fidelity to recognize the AUG start codon. Two mutants were identified to have dominant missense mutations in iftb-1, which encodes the beta-subunit of eIF2 (eIF2beta). Both mutations occur in a conserved region located outside of the C2-C2 zinc finger domain where yeast SUI3 mutations are localized in Saccharomyces cerevisiae eIF2beta. C. elegans iftb-1, as well as mutant eIF2betas carrying the equivalent SUI3 mutations, are able to initiate translation at non-AUG codons that retain two potential base-pairing interactions with the anticodon of the initiator methionyl tRNA. These analyses further support the critical role of eIF2beta in start codon selection, and two functional domains within eIF2beta are likely involved, one defined by our C. elegans mutants and the other by the yeast SUI3 mutants.
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Affiliation(s)
- Yinhua Zhang
- New England Biolabs, Ipswich, Massachusetts 01938
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