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Protein folding in vitro and in the cell: From a solitary journey to a team effort. Biophys Chem 2022; 287:106821. [PMID: 35667131 PMCID: PMC9636488 DOI: 10.1016/j.bpc.2022.106821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 04/18/2022] [Accepted: 04/21/2022] [Indexed: 12/22/2022]
Abstract
Correct protein folding is essential for the health and function of living organisms. Yet, it is not well understood how unfolded proteins reach their native state and avoid aggregation, especially within the cellular milieu. Some proteins, especially small, single-domain and apparent two-state folders, successfully attain their native state upon dilution from denaturant. Yet, many more proteins undergo misfolding and aggregation during this process, in a concentration-dependent fashion. Once formed, native and aggregated states are often kinetically trapped relative to each other. Hence, the early stages of protein life are absolutely critical for proper kinetic channeling to the folded state and for long-term solubility and function. This review summarizes current knowledge on protein folding/aggregation mechanisms in buffered solution and within the bacterial cell, highlighting early stages. Remarkably, teamwork between nascent chain, ribosome, trigger factor and Hsp70 molecular chaperones enables all proteins to overcome aggregation propensities and reach a long-lived bioactive state.
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2
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Matavacas J, von Wachenfeldt C. Update on the Protein Homeostasis Network in Bacillus subtilis. Front Microbiol 2022; 13:865141. [PMID: 35350626 PMCID: PMC8957991 DOI: 10.3389/fmicb.2022.865141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 02/15/2022] [Indexed: 11/13/2022] Open
Abstract
Protein homeostasis is fundamental to cell function and survival. It relies on an interconnected network of processes involving protein synthesis, folding, post-translational modification and degradation as well as regulators of these processes. Here we provide an update on the roles, regulation and subcellular localization of the protein homeostasis machinery in the Gram-positive model organism Bacillus subtilis. We discuss emerging ideas and current research gaps in the field that, if tackled, increase our understanding of how Gram-positive bacteria, including several human pathogens, maintain protein homeostasis and cope with stressful conditions that challenge their survival.
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Choudhury M, Dhara A, Kumar M. Trigger Factor in Association with the ClpP1P2 Heterocomplex of Leptospira Promotes Protease/Peptidase Activity. ACS OMEGA 2021; 6:1400-1409. [PMID: 33490799 PMCID: PMC7818586 DOI: 10.1021/acsomega.0c05057] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 12/28/2020] [Indexed: 05/07/2023]
Abstract
The genomic analysis of Leptospira reveals a trigger factor (TF) encoding gene (tig) to be colocalized along with the clpP1 and clpX. The TF is a crouching dragon-like protein known to be a ribosome-associated chaperone that is involved in cotranslational protein folding in bacteria in an ATP-independent mode. In Leptospira, tig is localized upstream of the clpP1 with a short (4 bp) overlap. In the present study, we document the distinctive role of Leptospira TF (LinTF) in the caseinolytic protease (ClpP) system. The recombinant LinTF (rLinTF) was found to improve the peptidase or protease activity of the ClpP1P2 heterocomplex and ClpXP1P2 complex, respectively, on model substrates. In addition, on supplementation of rLinTF to rClpP1P2 bound to its physiological ATPase chaperone ClpX or the antibiotic analogue acyldepsipeptide (ADEP), an augmentation in the activity of ClpP1P2 was observed. These studies underscore the novel role of LinTF in aiding the caseinolytic protease activity of Leptospira. Supplementation of rLinTF to a peptidase assay of rClpP1P2 conditionally in the presence of a salt (sodium citrate) with high Hofmeister strength led us to speculate that rLinTF may have a role in the assembly of multimeric proteins. The deletion of one of the arms (arm-2) of the LinTF structure from the carboxy terminal domain indicated a reduction in its capacity to stimulate rClpP1P2 activity. Thus, the C-terminal domain of LinTF may have a role in the assembly of multimeric ClpP protein, leading to enhancement of ClpP activity.
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Affiliation(s)
| | | | - Manish Kumar
- . Phone: +91-361-258-2230. Fax: +91-361-258-2249
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4
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Vignesh R, Aradhyam GK. A Change in Domain Cooperativity Drives the Function of Calnuc. Biochemistry 2020; 59:2507-2517. [PMID: 32543177 DOI: 10.1021/acs.biochem.0c00207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
With the increasing incidence of neurodegenerative disorders, there is an urgent need to understand the protein folding process. Examining the folding process of multidomain proteins remains a prime challenge, as their complex conformational dynamics make them highly susceptible to misfolding and/or aggregation. The presence of multiple domains in a protein can lead to interaction between the partially folded domains, thereby driving misfolding and/or aggregation. Calnuc is one such multidomain protein for which Ca2+ binding plays a pivotal role in governing its structural dynamics and stability and, presumably, in directing its interactions with other proteins. We demonstrate differential structural dynamics between the Ca2+-free and Ca2+-bound forms of calnuc. In the absence of Ca2+, full-length calnuc displays equilibrium structural transitions with four intermediate states, reporting a sum of the behavioral properties of its individual domains. Fragment-based studies illustrate the sequential events of structure adoption proceeding in the following order: EF domain followed by the NT and LZ domains in the apo state. On the other hand, Ca2+ binding increases domain cooperativity and enables the protein to fold as a single unit. Single-tryptophan mutant proteins, designed in a domain-dependent manner, confirm an increase in the number of interdomain interactions in the Ca2+-bound form as compared to the Ca2+-free state of the protein, thereby providing insight into its folding process. The attenuated domain crosstalk in apo-calnuc is likely to influence and regulate its physiologically important intermolecular interactions.
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Affiliation(s)
- Ravichandran Vignesh
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
| | - Gopala Krishna Aradhyam
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India
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5
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Biswas A, Ghosh S, Sinha D, Dutta A, Seal S, Bagchi A, Sau S. Dimerization ability, denaturation mechanism, and the stability of a staphylococcal phage repressor and its two domains. Int J Biol Macromol 2019; 124:903-914. [DOI: 10.1016/j.ijbiomac.2018.11.263] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/27/2018] [Accepted: 11/27/2018] [Indexed: 11/29/2022]
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6
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Bonner JM, Boulianne GL. Diverse structures, functions and uses of FK506 binding proteins. Cell Signal 2017; 38:97-105. [DOI: 10.1016/j.cellsig.2017.06.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 06/15/2017] [Accepted: 06/20/2017] [Indexed: 02/08/2023]
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7
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Ries F, Carius Y, Rohr M, Gries K, Keller S, Lancaster CRD, Willmund F. Structural and molecular comparison of bacterial and eukaryotic trigger factors. Sci Rep 2017; 7:10680. [PMID: 28878399 PMCID: PMC5587573 DOI: 10.1038/s41598-017-10625-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Accepted: 08/11/2017] [Indexed: 12/04/2022] Open
Abstract
A considerably small fraction of approximately 60–100 proteins of all chloroplast proteins are encoded by the plastid genome. Many of these proteins are major subunits of complexes with central functions within plastids. In comparison with other subcellular compartments and bacteria, many steps of chloroplast protein biogenesis are not well understood. We report here on the first study of chloroplast-localised trigger factor. In bacteria, this molecular chaperone is known to associate with translating ribosomes to facilitate the folding of newly synthesized proteins. Chloroplast trigger factors of the unicellular green algae Chlamydomonas reinhardtii and the vascular land plant Arabidopsis thaliana were characterized by biophysical and structural methods and compared to the Escherichia coli isoform. We show that chloroplast trigger factor is mainly monomeric and displays only moderate stability against thermal unfolding even under mild heat-stress conditions. The global shape and conformation of these proteins were determined in solution by small-angle X-ray scattering and subsequent ab initio modelling. As observed for bacteria, plastidic trigger factors have a dragon-like structure, albeit with slightly altered domain arrangement and flexibility. This structural conservation despite low amino acid sequence homology illustrates a remarkable evolutionary robustness of chaperone conformations across various kingdoms of life.
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Affiliation(s)
- Fabian Ries
- Molecular Genetics of Eukaryotes, University of Kaiserslautern, Erwin-Schrödinger-Str. 70, 67663, Kaiserslautern, Germany
| | - Yvonne Carius
- Department of Structural Biology, Saarland University, Center of Human and Molecular Biology (ZHMB), Faculty of Medicine Building 60, 66421, Homburg, Germany
| | - Marina Rohr
- Molecular Genetics of Eukaryotes, University of Kaiserslautern, Erwin-Schrödinger-Str. 70, 67663, Kaiserslautern, Germany
| | - Karin Gries
- Molecular Genetics of Eukaryotes, University of Kaiserslautern, Erwin-Schrödinger-Str. 70, 67663, Kaiserslautern, Germany
| | - Sandro Keller
- Molecular Biophysics, University of Kaiserslautern, Erwin-Schrödinger-Str. 13, 67663, Kaiserslautern, Germany
| | - C Roy D Lancaster
- Department of Structural Biology, Saarland University, Center of Human and Molecular Biology (ZHMB), Faculty of Medicine Building 60, 66421, Homburg, Germany.
| | - Felix Willmund
- Molecular Genetics of Eukaryotes, University of Kaiserslautern, Erwin-Schrödinger-Str. 70, 67663, Kaiserslautern, Germany.
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8
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Singhal K, Vreede J, Mashaghi A, Tans SJ, Bolhuis PG. Hydrophobic collapse of trigger factor monomer in solution. PLoS One 2013; 8:e59683. [PMID: 23565160 PMCID: PMC3615003 DOI: 10.1371/journal.pone.0059683] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 02/16/2013] [Indexed: 11/30/2022] Open
Abstract
Trigger factor (TF) is a chaperone, found in bacterial cells and chloroplasts, that interacts with nascent polypeptide chains to suppress aggregation. While its crystal structure has been resolved, the solution structure and dynamics are largely unknown. We performed multiple molecular dynamics simulations on Trigger factor in solution, and show that its tertiary domains display collective motions hinged about inter-domain linkers with minimal or no loss in secondary structure. Moreover, we find that isolated TF typically adopts a collapsed state, with the formation of domain pairs. This collapse of TF in solution is induced by hydrophobic interactions and stabilised by hydrophilic contacts. To determine the nature of the domain interactions, we analysed the hydrophobicity of the domain surfaces by using the hydrophobic probe method of Acharya et al.[1], [2], as the standard hydrophobicity scales predictions are limited due to the complex environment. We find that the formation of domain pairs changes the hydrophobic map of TF, making the N-terminal and arm2 domain pair more hydrophilic and the head and arm1 domain pair more hydrophobic. These insights into the dynamics and interactions of the TF domains are important to eventually understand chaperone-substrate interactions and chaperone function.
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Affiliation(s)
- Kushagra Singhal
- van ‘t Hoff Institute of Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Jocelyne Vreede
- van ‘t Hoff Institute of Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Alireza Mashaghi
- Department of Systems Biophysics, FOM Institute AMOLF, Amsterdam, The Netherlands
| | - Sander J. Tans
- Department of Systems Biophysics, FOM Institute AMOLF, Amsterdam, The Netherlands
| | - Peter G. Bolhuis
- van ‘t Hoff Institute of Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
- * E-mail:
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9
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Intracellularly induced cyclophilins play an important role in stress adaptation and virulence of Brucella abortus. Infect Immun 2012; 81:521-30. [PMID: 23230297 DOI: 10.1128/iai.01125-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Brucella is an intracellular bacterial pathogen that causes the worldwide zoonotic disease brucellosis. Brucella virulence relies on its ability to transition to an intracellular lifestyle within host cells. Thus, this pathogen must sense its intracellular localization and then reprogram gene expression for survival within the host cell. A comparative proteomic investigation was performed to identify differentially expressed proteins potentially relevant for Brucella intracellular adaptation. Two proteins identified as cyclophilins (CypA and CypB) were overexpressed in the intracellular environment of the host cell in comparison to laboratory-grown Brucella. To define the potential role of cyclophilins in Brucella virulence, a double-deletion mutant was constructed and its resulting phenotype was characterized. The Brucella abortus ΔcypAB mutant displayed increased sensitivity to environmental stressors, such as oxidative stress, pH, and detergents. In addition, the B. abortus ΔcypAB mutant strain had a reduced growth rate at lower temperature, a phenotype associated with defective expression of cyclophilins in other microorganisms. The B. abortus ΔcypAB mutant also displays reduced virulence in BALB/c mice and defective intracellular survival in HeLa cells. These findings suggest that cyclophilins are important for Brucella virulence and survival in the host cells.
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10
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Geitner AJ, Schmid FX. Combination of the Human Prolyl Isomerase FKBP12 with Unrelated Chaperone Domains Leads to Chimeric Folding Enzymes with High Activity. J Mol Biol 2012; 420:335-49. [DOI: 10.1016/j.jmb.2012.04.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 04/10/2012] [Accepted: 04/18/2012] [Indexed: 12/11/2022]
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11
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Jana B, Bandhu A, Mondal R, Biswas A, Sau K, Sau S. Domain Structure and Denaturation of a Dimeric Mip-like Peptidyl-Prolyl cis–trans Isomerase from Escherichia coli. Biochemistry 2012; 51:1223-37. [PMID: 22263615 DOI: 10.1021/bi2015037] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Biswanath Jana
- Department of Biochemistry, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata 700054,
West Bengal, India
| | - Amitava Bandhu
- Department of Biochemistry, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata 700054,
West Bengal, India
| | - Rajkrishna Mondal
- Department of Biochemistry, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata 700054,
West Bengal, India
| | - Anindya Biswas
- Department of Biochemistry, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata 700054,
West Bengal, India
| | - Keya Sau
- Department
of Biotechnology, Haldia Institute of Technology, PO-HIT, Dt-Purba Medinipur,
Pin 721657, West Bengal, India
| | - Subrata Sau
- Department of Biochemistry, Bose Institute, P-1/12, CIT Scheme VII M, Kolkata 700054,
West Bengal, India
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12
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Martinez-Hackert E, Hendrickson WA. Structural analysis of protein folding by the long-chain archaeal chaperone FKBP26. J Mol Biol 2011; 407:450-64. [PMID: 21262232 DOI: 10.1016/j.jmb.2011.01.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 01/05/2011] [Accepted: 01/12/2011] [Indexed: 11/17/2022]
Abstract
In the cell, protein folding is mediated by folding catalysts and chaperones. The two functions are often linked, especially when the catalytic module forms part of a multidomain protein, as in Methanococcus jannaschii peptidyl-prolyl cis/trans isomerase FKBP26. Here, we show that FKBP26 chaperone activity requires both a 50-residue insertion in the catalytic FKBP domain, also called 'Insert-in-Flap' or IF domain, and an 80-residue C-terminal domain. We determined FKBP26 structures from four crystal forms and analyzed chaperone domains in light of their ability to mediate protein-protein interactions. FKBP26 is a crescent-shaped homodimer. We reason that folding proteins are bound inside the large crescent cleft, thus enabling their access to inward-facing peptidyl-prolyl cis/trans isomerase catalytic sites and ipsilateral chaperone domain surfaces. As these chaperone surfaces participate extensively in crystal lattice contacts, we speculate that the observed lattice contacts reflect a proclivity for protein associations and represent substrate interactions by FKBP26 chaperone domains. Finally, we find that FKBP26 is an exceptionally flexible molecule, suggesting a mechanism for nonspecific substrate recognition.
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Affiliation(s)
- Erik Martinez-Hackert
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
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13
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Dimou M, Venieraki A, Liakopoulos G, Kouri ED, Tampakaki A, Katinakis P. Gene Expression and Biochemical Characterization of Azotobacter vinelandii Cyclophilins and Protein Interaction Studies of the Cytoplasmic Isoform with dnaK and lpxH. J Mol Microbiol Biotechnol 2011; 20:176-90. [DOI: 10.1159/000329486] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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14
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Hoffmann A, Bukau B, Kramer G. Structure and function of the molecular chaperone Trigger Factor. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:650-61. [PMID: 20132842 DOI: 10.1016/j.bbamcr.2010.01.017] [Citation(s) in RCA: 158] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 01/22/2010] [Indexed: 01/16/2023]
Abstract
Newly synthesized proteins often require the assistance of molecular chaperones to efficiently fold into functional three-dimensional structures. At first, ribosome-associated chaperones guide the initial folding steps and protect growing polypeptide chains from misfolding and aggregation. After that folding into the native structure may occur spontaneously or require support by additional chaperones which do not bind to the ribosome such as DnaK and GroEL. Here we review the current knowledge on the best-characterized ribosome-associated chaperone at present, the Escherichia coli Trigger Factor. We describe recent progress on structural and dynamic aspects of Trigger Factor's interactions with the ribosome and substrates and discuss how these interactions affect co-translational protein folding. In addition, we discuss the newly proposed ribosome-independent function of Trigger Factor as assembly factor of multi-subunit protein complexes. Finally, we cover the functional cooperation between Trigger Factor, DnaK and GroEL in folding of cytosolic proteins and the interplay between Trigger Factor and other ribosome-associated factors acting in enzymatic processing and translocation of nascent polypeptide chains.
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Affiliation(s)
- Anja Hoffmann
- Zentrum für Molekulare Biologie der Universität Heidelberg, Heidelberg, Germany
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15
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A method for generating precise gene deletions and insertions in Escherichia coli. World J Microbiol Biotechnol 2010; 26:1323-9. [DOI: 10.1007/s11274-009-0305-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2009] [Accepted: 12/30/2009] [Indexed: 11/26/2022]
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16
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Fan DJ, Ding YW, Zhou JM. Structural rearrangements and the unfolding mechanism of a Trigger Factor mutant studied by multiple structural probes. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2009; 1794:944-52. [DOI: 10.1016/j.bbapap.2009.03.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 03/10/2009] [Accepted: 03/16/2009] [Indexed: 10/21/2022]
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17
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Batey S, Nickson AA, Clarke J. Studying the folding of multidomain proteins. HFSP JOURNAL 2008; 2:365-77. [PMID: 19436439 DOI: 10.2976/1.2991513] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2008] [Indexed: 11/19/2022]
Abstract
There have been relatively few detailed comprehensive studies of the folding of protein domains (or modules) in the context of their natural covalently linked neighbors. This is despite the fact that a significant proportion of the proteome consists of multidomain proteins. In this review we highlight some key experimental investigations of the folding of multidomain proteins to draw attention to the difficulties that can arise in analyzing such systems. The evidence suggests that interdomain interactions can significantly affect stability, folding, and unfolding rates. However, preliminary studies suggest that folding pathways are unaffected-to this extent domains can be truly considered to be independent folding units. Nonetheless, it is clear that interactions between domains cannot be ignored, in particular when considering the effects of mutations.
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Affiliation(s)
- Sarah Batey
- Department of Chemistry, MRC Centre for Protein Engineering, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
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18
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Schlünzen F, Wilson DN, Tian P, Harms JM, McInnes SJ, Hansen HAS, Albrecht R, Buerger J, Wilbanks SM, Fucini P. The binding mode of the trigger factor on the ribosome: implications for protein folding and SRP interaction. Structure 2008; 13:1685-94. [PMID: 16271892 DOI: 10.1016/j.str.2005.08.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Revised: 08/02/2005] [Accepted: 08/03/2005] [Indexed: 01/21/2023]
Abstract
This study presents the X-ray structure of the N-terminal binding domain of the D. radiodurans trigger factor (TF) in complex with the D. radiodurans large ribosomal subunit. At 3.35 A, a complete description of the interactions with ribosomal proteins L23, L29, and 23S rRNA are disclosed, many of which differ from those found previously for a heterologous bacterial-archaeal TF-ribosome complex. The beta hairpin loop of eubacterial L24, which is shorter in archaeal ribosomes, contacts the TF and severely diminishes the molecular cradle proposed to exist between the TF and ribosome. Bound to the ribosome, TF exposes a hydrophobic crevice large enough to accommodate the nascent polypeptide chain. Superimposition of the full-length TF and the signal-recognition particle (SRP) onto the complex shows that simultaneous cohabitation is possible, in agreement with biochemical data, and suggests a model for the interplay of TF, SRP, and the nascent chain during translation.
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Affiliation(s)
- Frank Schlünzen
- Max-Planck Institute for Molecular Genetics, Ihnestrasse 73, D-14195 Berlin, Germany.
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Tsuji T, Nagata T, Yanagawa H. N- and C-terminal Fragments of a Globular Protein Constructed by Elongation of Modules as a Units Associated for Functional Complementation. J Biochem 2008; 144:513-21. [DOI: 10.1093/jb/mvn099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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20
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Thermal unfolding of Escherichia coli trigger factor studied by ultra-sensitive differential scanning calorimetry. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:1728-34. [PMID: 18539163 DOI: 10.1016/j.bbapap.2008.05.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2008] [Revised: 04/22/2008] [Accepted: 05/08/2008] [Indexed: 11/22/2022]
Abstract
Temperature-induced unfolding of Escherichia coli trigger factor (TF) and its domain truncation mutants, NM and MC, were studied by ultra-sensitive differential scanning calorimetry (UC-DSC). Detailed thermodynamic analysis showed that thermal induced unfolding of TF and MC involves population of dimeric intermediates. In contrast, the thermal unfolding of the NM mutant involves population of only monomeric states. Covalent cross-linking experiments confirmed the presence of dimeric intermediates during thermal unfolding of TF and MC. These data not only suggest that the dimeric form of TF is extremely resistant to thermal unfolding, but also provide further evidence that the C-terminal domain of TF plays a vital role in forming and stabilizing the dimeric structure of the TF molecule. Since TF is the first molecular chaperone that nascent polypeptides encounter in eubacteria, the stable dimeric intermediates of TF populated during thermal denaturation might be important in responding to stress damage to the cell, such as heat shock.
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Anderson E, Cole JL. Domain stabilities in protein kinase R (PKR): evidence for weak interdomain interactions. Biochemistry 2008; 47:4887-97. [PMID: 18393532 DOI: 10.1021/bi702211j] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
PKR (protein kinase R) is induced by interferon and is a key component of the innate immunity antiviral pathway. Upon binding dsRNA, PKR undergoes autophosphorylation reactions that activate the kinase, leading it to phosphorylate eIF2alpha, thus inhibiting protein synthesis in virally infected cells. PKR contains a dsRNA-binding domain (dsRBD) and a kinase domain. The dsRBD is composed of two tandem dsRNA-binding motifs. An autoinhibition model for PKR has been proposed, whereby dsRNA binding activates the enzyme by inducing a conformational change that relieves the latent enzyme of the inhibition that is mediated by the interaction of the dsRBD with the kinase. However, recent biophysical data support an open conformation for the latent enzyme, where activation is mediated by dimerization of PKR induced upon binding dsRNA. We have probed the importance of interdomain contacts by comparing the relative stabilities of isolated domains with the same domain in the context of the intact enzyme using equilibrium chemical denaturation experiments. The two dsRNA-binding motifs fold independently, with the C-terminal motif exhibiting greater stability. The kinase domain is stabilized by about 1.5 kcal/mol in the context of the holenzyme, and we detect low-affinity binding of the kinase and dsRBD constructs in solution, indicating that these domains interact weakly. Limited proteolysis measurements confirm the expected domain boundaries and reveal that the activation loop in the kinase is accessible to cleavage and unstructured. Autophosphorylation induces a conformation change that blocks proteolysis of the activation loop.
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Affiliation(s)
- Eric Anderson
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, Connecticut 06269-3125, USA
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22
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Abstract
Guanidine induced equilibrium and kinetic folding of a variant of green fluorescent protein (F99S/M153T/V163A, GFPuv) was studied. Using manual mixing and stopped-flow techniques, we combined different probes, including tryptophan fluorescence, chromophore fluorescence and reactivity with DTNB, to trace the spontaneous and TF-assisted folding of guanidine denatured GFPuv. We found that both unfolding and refolding of GFPuv occurred in a stepwise manner and a stable intermediate was populated under equilibrium conditions. The thermodynamic parameters obtained show that the intermediate state of GFPuv is quite compact compared to the denatured state and most of the green fluorescence is retained in this state. By studying GFPuv folding assisted by TF and a number of TF mutants, we found that wild-type TF catalyzes proline isomerization and accelerates the folding rate at low TF concentrations, but retards GFPuv folding and decelerates the folding rate at high TF concentrations. This reflects the two activities of TF, as an enzyme and as a chaperone. A general mechanism of TF assisted protein folding is discussed.
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Affiliation(s)
- Jiang-Bi Xie
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
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Shi Y, Fan DJ, Li SX, Zhang HJ, Perrett S, Zhou JM. Identification of a potential hydrophobic peptide binding site in the C-terminal arm of trigger factor. Protein Sci 2007; 16:1165-75. [PMID: 17525465 PMCID: PMC2206664 DOI: 10.1110/ps.062623707] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Trigger factor (TF) is the first chaperone to interact with nascent chains and facilitate their folding in bacteria. Escherichia coli TF is 432 residues in length and contains three domains with distinct structural and functional properties. The N-terminal domain of TF is important for ribosome binding, and the M-domain carries the PPIase activity. However, the function of the C-terminal domain remains unclear, and the residues or regions directly involved in substrate binding have not yet been identified. Here, a hydrophobic probe, bis-ANS, was used to characterize potential substrate-binding regions. Results showed that bis-ANS binds TF with a 1:1 stoichiometry and a K(d) of 16 microM, and it can be covalently incorporated into TF by UV-light irradiation. A single bis-ANS-labeled peptide was obtained by tryptic digestion and identified by MALDI-TOF mass spectrometry as Asn391-Lys392. In silico docking analysis identified a single potential binding site for bis-ANS on the TF molecule, which is adjacent to this dipeptide and lies in the pocket formed by the C-terminal arms. The bis-ANS-labeled TF completely lost the ability to assist GAPDH or lysozyme refolding and showed increased protection toward cleavage by alpha-chymotrypsin, suggesting blocking of hydrophobic residues. The C-terminal truncation mutant TF389 also showed no chaperone activity and could not bind bis-ANS. These results suggest that bis-ANS binding may mimic binding of a substrate peptide and that the C-terminal region of TF plays an important role in hydrophobic binding and chaperone function.
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Affiliation(s)
- Yi Shi
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
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24
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Knappe TA, Eckert B, Schaarschmidt P, Scholz C, Schmid FX. Insertion of a Chaperone Domain Converts FKBP12 into a Powerful Catalyst of Protein Folding. J Mol Biol 2007; 368:1458-68. [PMID: 17397867 DOI: 10.1016/j.jmb.2007.02.097] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Accepted: 02/28/2007] [Indexed: 11/28/2022]
Abstract
The catalytic activity of human FKBP12 as a prolyl isomerase is high towards short peptides, but very low in proline-limited protein folding reactions. In contrast, the SlyD proteins, which are members of the FKBP family, are highly active as folding enzymes. They contain an extra "insert-in-flap" or IF domain near the prolyl isomerase active site. The excision of this domain did not affect the prolyl isomerase activity of SlyD from Escherichia coli towards short peptide substrates but abolished its catalytic activity in proline-limited protein folding reactions. The reciprocal insertion of the IF domain of SlyD into human FKBP12 increased its folding activity 200-fold and generated a folding catalyst that is more active than SlyD itself. The IF domain binds to refolding protein chains and thus functions as a chaperone module. A prolyl isomerase catalytic site and a separate chaperone site with an adapted affinity for refolding protein chains are the key elements for a productive coupling between the catalysis of prolyl isomerization and conformational folding in the enzymatic mechanisms of SlyD and other prolyl isomerases, such as trigger factor and FkpA.
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Affiliation(s)
- Thomas A Knappe
- Laboratorium für Biochemie, Universität Bayreuth, D-95440 Bayreuth, Germany
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25
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Batey S, Clarke J. Apparent cooperativity in the folding of multidomain proteins depends on the relative rates of folding of the constituent domains. Proc Natl Acad Sci U S A 2006; 103:18113-8. [PMID: 17108086 PMCID: PMC1636339 DOI: 10.1073/pnas.0604580103] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Approximately 75% of eukaryotic proteins contain more than one so-called independently folding domain. However, there have been relatively few systematic studies to investigate the effect of interdomain interactions on protein stability and fewer still on folding kinetics. We present the folding of pairs of three-helix bundle spectrin domains as a paradigm to indicate how complex such an analysis can be. Equilibrium studies show an increase in denaturant concentration required to unfold the domains with only a single unfolding transition; however, in some cases, this is not accompanied by the increase in m value, which would be expected if the protein is a truly cooperative, all-or-none system. We analyze the complex kinetics of spectrin domain pairs, both wild-type and carefully selected mutants. By comparing these pairs, we are able to demonstrate that equilibrium data alone are insufficient to describe the folding of multidomain proteins and to quantify the effects that one domain can have on its neighbor.
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Affiliation(s)
- Sarah Batey
- Department of Chemistry, University of Cambridge, Medical Research Council Centre for Protein Engineering, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Jane Clarke
- Department of Chemistry, University of Cambridge, Medical Research Council Centre for Protein Engineering, Lensfield Road, Cambridge CB2 1EW, United Kingdom
- To whom correspondence should be addressed. E-mail:
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26
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The C-terminal Domain of Escherichia coli Trigger Factor Represents the Central Module of Its Chaperone Activity. J Biol Chem 2006. [DOI: 10.1016/s0021-9258(19)84110-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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27
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Merz F, Hoffmann A, Rutkowska A, Zachmann-Brand B, Bukau B, Deuerling E. The C-terminal domain of Escherichia coli trigger factor represents the central module of its chaperone activity. J Biol Chem 2006; 281:31963-71. [PMID: 16926148 DOI: 10.1074/jbc.m605164200] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In bacteria, ribosome-bound Trigger Factor assists the folding of newly synthesized proteins. The N-terminal domain (N) of Trigger Factor mediates ribosome binding, whereas the middle domain (P) harbors peptidyl-prolyl isomerase activity. The function of the C-terminal domain (C) has remained enigmatic due to structural instability in isolation. Here, we have characterized a stabilized version of the C domain (C(S)), designed on the basis of the recently solved atomic structure of Trigger Factor. Strikingly, only the isolated C(S) domain or domain combinations thereof (NC(S), PC(S)) revealed substantial chaperone activity in vitro and in vivo. Furthermore, to disrupt the C domain without affecting the overall Trigger Factor structure, we generated a mutant (Delta53) by deletion of the C-terminal 53 amino acid residues. This truncation caused the complete loss of the chaperone activity of Trigger Factor in vitro and severely impaired its function in vivo. Therefore, we conclude that the chaperone activity of Trigger Factor critically depends on its C-terminal domain as the central structural chaperone module. Intriguingly, a structurally similar module is found in the periplasmic chaperone SurA and in MPN555, a protein of unknown function. We speculate that this conserved module can exist solely or in combination with additional domains to fulfill diverse chaperone functions in the cell.
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Affiliation(s)
- Frieder Merz
- Zentrum für Molekulare Biologie der Universität Heidelberg Im Neuenheimer Feld 282, Universität Heidelberg, 69120 Heidelberg, Germany
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28
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Scholz C, Eckert B, Hagn F, Schaarschmidt P, Balbach J, Schmid FX. SlyD proteins from different species exhibit high prolyl isomerase and chaperone activities. Biochemistry 2006; 45:20-33. [PMID: 16388577 DOI: 10.1021/bi051922n] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
SlyD is a putative folding helper protein from the Escherichia coli cytosol, which consists of an N-terminal prolyl isomerase domain of the FKBP type and a presumably unstructured C-terminal tail. We produced truncated versions without this tail (SlyD) for SlyD from E. coli, as well as for the SlyD orthologues from Yersinia pestis, Treponema pallidum, Pasteurella multocida, and Vibrio cholerae. They are monomeric in solution and unfold reversibly. All SlyD variants catalyze the proline-limited refolding of ribonuclease T1 with very high efficiencies, and the specificity constants (kcat/KM) are equal to approximately 10(6) M(-1) s(-1). These large values originate from the high affinities of the SlyD orthologues for unfolded RCM-T1, which are reflected in low KM values of approximately 1 microM. SlyD also exhibits pronounced chaperone properties. Permanently unfolded proteins bind with high affinity to SlyD and thus inhibit its prolyl isomerase activity. The unfolded protein chains do not need to contain proline residues to be recognized and bound by SlyD. The conservation of prolyl isomerase activity and chaperone properties within the SlyD family suggests that these proteins might act as true folding helpers in the bacterial cytosol. The SlyD proteins are also well suited for biotechnological applications. As fusion partners they facilitate the refolding and increase the solubility of aggregation-prone proteins such as the gp41 ectodomain fragment of HIV-1.
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Affiliation(s)
- Christian Scholz
- Roche Diagnostics GmbH, Nonnenwald 2, D-82377 Penzberg, Germany.
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29
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Li S, Nosenko T, Hackett JD, Bhattacharya D. Phylogenomic analysis identifies red algal genes of endosymbiotic origin in the chromalveolates. Mol Biol Evol 2005; 23:663-74. [PMID: 16357039 DOI: 10.1093/molbev/msj075] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Endosymbiosis has spread photosynthesis to many branches of the eukaryotic tree; however, the history of photosynthetic organelle (plastid) gain and loss remains controversial. Fortuitously, endosymbiosis may leave a genomic footprint through the transfer of endosymbiont genes to the "host" nucleus (endosymbiotic gene transfer, EGT). EGT can be detected through comparison of host genomes to uncover the history of past plastid acquisitions. Here we focus on a lineage of chlorophyll c-containing algae and protists ("chromalveolates") that are postulated to share a common red algal secondary endosymbiont. This plastid is originally of cyanobacterial origin through primary endosymbiosis and is closely related among the Plantae (i.e., red, green, and glaucophyte algae). To test these ideas, an automated phylogenomics pipeline was used with a novel unigene data set of 5,081 expressed sequence tags (ESTs) from the haptophyte alga Emiliania huxleyi and genome or EST data from other chromalveolates, red algae, plants, animals, fungi, and bacteria. We focused on nuclear-encoded proteins that are targeted to the plastid to express their function because this group of genes is expected to have phylogenies that are relatively easy to interpret. A total of 708 genes were identified in E. huxleyi that had a significant Blast hit to at least one other taxon in our data set. Forty-six of the alignments that were derived from the 708 genes contained at least one other chromalveolate (i.e., besides E. huxleyi), red and/or green algae (or land plants), and one or more cyanobacteria, whereas 15 alignments contained E. huxleyi, one or more other chromalveolates, and only cyanobacteria. Detailed phylogenetic analyses of these data sets turned up 19 cases of EGT that did not contain significant paralogy and had strong bootstrap support at the internal nodes, allowing us to confidently identify the source of the plastid-targeted gene in E. huxleyi. A total of 17 genes originated from the red algal lineage, whereas 2 genes were of green algal origin. Our data demonstrate the existence of multiple red algal genes that are shared among different chromalveolates, suggesting that at least a subset of this group may share a common origin.
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Affiliation(s)
- Shenglan Li
- Department of Biological Sciences and Roy J. Carver Center for Comparative Genomics, University of Iowa, USA
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30
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Zeng LL, Yu L, Li ZY, Perrett S, Zhou JM. Effect of C-terminal truncation on the molecular chaperone function and dimerization of Escherichia coli trigger factor. Biochimie 2005; 88:613-9. [PMID: 16380200 DOI: 10.1016/j.biochi.2005.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2005] [Accepted: 11/14/2005] [Indexed: 11/27/2022]
Abstract
To examine the role of the C-terminal domain in the chaperone function of trigger factor (TF), a number of truncation mutants were constructed, namely: TF419, TF389, TF380, TF360, TF344, and TF251, in which the C-terminal 13, 43, 52, 72, 88 residues or the entire C-domain were deleted, respectively. Co-expression of mutant chicken adenylate kinase (AK) with TF and the C-terminal truncation mutants was achieved using a plasmid pBVAT that allows expression of TF and AK from a single plasmid. The results show that truncation of the C-terminus of TF has only minor effect on its ability to assist AK refolding in vivo. Further, ribosome-binding experiments indicate that C-terminal truncation mutants can still bind to the ribosome and the presence of the C-terminus may in fact lower the affinity of TF for the ribosome in vivo. This indicates that the C-domain of trigger factor may not be essential for the ribosome-associated molecular chaperone function of TF. However, the purified TF C-terminal truncation mutants had a dramatically reduced ability to assist rabbit muscle GAPDH refolding in vitro and a reduced tendency to dimerize. This shows that the structural integrity of the C-terminus contributes to both the chaperone function of TF and the stability of the dimeric form.
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Affiliation(s)
- Li-Ling Zeng
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
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31
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Liu CP, Li ZY, Huang GC, Perrett S, Zhou JM. Two distinct intermediates of trigger factor are populated during guanidine denaturation. Biochimie 2005; 87:1023-31. [PMID: 15927341 DOI: 10.1016/j.biochi.2005.03.017] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2004] [Revised: 03/04/2005] [Accepted: 03/17/2005] [Indexed: 11/21/2022]
Abstract
Trigger factor (TF) is an important catalyst of nascent peptide folding and possesses both peptidyl-prolyl cis-trans isomerase (PPIase) and chaperone activities. TF has a modular structure, containing three domains with distinct structural and functional properties. The guanidine hydrochloride (GuHCl) induced unfolding of TF was investigated by monitoring Trp fluorescence, far-UV CD, second-derivative UV absorption, enzymatic and chaperone activities, chemical crosslinking and binding of the hydrophobic dye, 1-anilinonaphthalene-8-sulfonate (ANS); and was compared to the urea induced unfolding. The native state of TF was found to bind ANS in 1:1 stoichiometry with a K(d) of 84 microM. A native-like state, N', is stable around 0.5 M GuHCl, and shows increased ANS binding, while retaining PPIase activity and most secondary and tertiary structure, but loses chaperone and dimerization activities, consistent with slight conformational rearrangement. A compact denatured state, I, is populated around 1.0 M GuHCl, is inactive and does not show significant binding to ANS. The data suggest that TF unfolds in a stepwise manner, consistent with its modular structure. The ability of TF to undergo structural rearrangement to maintain enzymatic activity while reducing chaperone and dimerization abilities may be related to the physiological function of TF.
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Affiliation(s)
- Chuan-Peng Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
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32
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Romano P, Gray J, Horton P, Luan S. Plant immunophilins: functional versatility beyond protein maturation. THE NEW PHYTOLOGIST 2005; 166:753-69. [PMID: 15869639 DOI: 10.1111/j.1469-8137.2005.01373.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Originally identified as the cellular targets of immunosuppressant drugs, the immunophilins encompass two ubiquitous protein families: the FK-506 binding proteins or FKBPs, and the cyclosporin-binding proteins or cyclophilins. Present in organisms ranging from bacteria to animals and plants, these proteins are characterized by their enzymatic activity; the peptidyl-prolyl cis-trans isomerization of polypeptides. Whilst this function is important for protein folding, it has formed the functional basis for more complex interactions between immunophilins and their target proteins. Beginning with a brief historical overview of the immunophilin family, and a representative illustration of the current state of knowledge that has accumulated for these proteins in diverse organisms, a detailed description is presented of the recent advances in the elucidation of the role of this ubiquitous protein family in plant biology. Though still in its infancy, investigation into the function of plant immunophilins has so far yielded interesting results--as a significant component of the chloroplast proteome, the abundance of immunophilins located in the thylakoid lumen suggests that these proteins may play important roles in this relatively uncharacterized subcellular compartment. Moreover, the importance of the complex multidomain immunophilins in functions pertaining to development is underscored by the strong phenotypes displayed by their corresponding mutants.
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Affiliation(s)
- Patrick Romano
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
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33
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Bobek J, Halada P, Angelis J, Vohradský J, Mikulík K. Activation and expression of proteins during synchronous germination of aerial spores of Streptomyces granaticolor. Proteomics 2005; 4:3864-80. [PMID: 15378695 DOI: 10.1002/pmic.200400818] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Synchronously germinating aerial spores of Streptomyces granaticolor were used to study protein activation and expression during the transition from dormant to metabolically active vegetative forms. The first phase of protein activation is associated with the solubility of proteins. Three major chaperones, DnaK, Trigger factor, and GroEL, were identified in spores. Enhancement in rate of protein synthesis during germination was accompanied by the association of TF and DnaK with ribosomes. During germination, the chaperones TF, GroEL, and DnaK undergo reversible phosphorylation. GroEL was phosphorylated on both Ser and Thr, whereas phosphorylation of DnaK and TF was detected on Thr only. A proteomic approach was used to gain more information on protein expression during germination on two types of media differing in the ability of cells to produce antibiotic granaticin. To obtain an overview of the metabolic activity of germinating spores, glycolytic enzymes, enzymes of citric acid cycle, metabolism of amino acids and nucleic acids, and components of the protein synthesis system were identified and analyzed using the proteomic database. The results were deposited on the SWICZ proteomic server and are accessible on http://proteom.biomed.cas.cz.
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Affiliation(s)
- Jan Bobek
- Institute of Microbiology of the Czech Academy of Sciences, Prague, Czech Republic
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34
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Scholz C, Schaarschmidt P, Engel AM, Andres H, Schmitt U, Faatz E, Balbach J, Schmid FX. Functional Solubilization of Aggregation-prone HIV Envelope Proteins by Covalent Fusion with Chaperone Modules. J Mol Biol 2005; 345:1229-41. [PMID: 15644217 DOI: 10.1016/j.jmb.2004.10.091] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2004] [Revised: 10/28/2004] [Accepted: 10/29/2004] [Indexed: 11/21/2022]
Abstract
The envelope proteins of human immunodeficiency virus (HIV) and human T-cell lymphotrophic virus (HTLV) mediate cell attachment and membrane fusion. For HIV-1, the precursor protein gp160 is cleaved proteolytically into two fragments, the surface-associated receptor binding subunit gp120 and the membrane spanning subunit gp41, which is involved in membrane fusion during virus entry. Soluble and immunoreactive variants of gp41 are essential for the reliable diagnosis of HIV-1 infections. Hitherto, gp41 was solubilized by adding detergents, or in acidic or alkaline solvents. We find that covalent fusions with SlyD or FkpA, two homodimeric Escherichia coli chaperones with peptidyl-prolyl isomerase activity, solubilize retroviral envelope proteins without compromising their immunological reactivity. gp41 from HIV-1, gp36 from HIV-2 and gp21 from HTLV could be expressed in large amounts in the Escherichia coli cytosol when fused with one or two subunits of SlyD or FkpA. The fusion proteins could be easily isolated and refolded, and showed high solubility and immunoreactivity, thus providing sensitive and reliable tools for diagnostic applications. Covalent fusions with SlyD or FkpA might be valuable generic tools for the solubilization and activation of aggregation-prone proteins.
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Affiliation(s)
- Christian Scholz
- Roche Diagnostics GmbH, Nonnenwald 2, D-82377 Penzberg, Germany.
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35
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Liu CP, Perrett S, Zhou JM. Dimeric trigger factor stably binds folding-competent intermediates and cooperates with the DnaK-DnaJ-GrpE chaperone system to allow refolding. J Biol Chem 2005; 280:13315-20. [PMID: 15632130 DOI: 10.1074/jbc.m414151200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Trigger factor (TF) is the first chaperone encountered by the nascent chain in bacteria and forms a stoichiometric complex with the ribosome. However, the functional significance of the high cytosolic concentration of uncomplexed TF, the majority of which is dimeric, is unknown. To gain insight into TF function, we investigated the TF concentration dependence of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) reactivation yield in the presence and absence of the DnaK-DnaJ-GrpE chaperone system in vitro. Cross-linking results indicate that the observed decrease in the reactivation yield of GAPDH at high concentrations of TF is due to the formation of a stable complex between TF dimer and GAPDH intermediates. In the absence of TF, or at low TF concentrations, the DnaK-DnaJ-GrpE chaperone system had negligible effect on the GAPDH refolding yield. However, GAPDH intermediates bound and held by dimeric TF could be specifically rescued by the DnaK-DnaJ-GrpE chaperone system in an ATP-dependent manner. This indicates the potential of TF, in its dimeric form, to act as a binding chaperone, maintaining non-native proteins in a refolding competent conformation and cooperating with downstream molecular chaperones to facilitate post-translational or post-stress protein folding.
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Affiliation(s)
- Chuan-Peng Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China
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36
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Ludlam AV, Moore BA, Xu Z. The crystal structure of ribosomal chaperone trigger factor from Vibrio cholerae. Proc Natl Acad Sci U S A 2004; 101:13436-41. [PMID: 15353602 PMCID: PMC518775 DOI: 10.1073/pnas.0405868101] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Trigger factor is a molecular chaperone that is present in all species of eubacteria. It binds to the ribosomal 50S subunit near the translation exit tunnel and is thought to be the first protein to interact with nascent polypeptides emerging from the ribosome. The chaperone has a peptidyl-prolyl cis-trans isomerase (PPIase) activity that catalyzes the rate-limiting proline isomerization in the protein-folding process. We have determined the crystal structure of nearly full-length trigger factor from Vibrio cholerae by x-ray crystallography at 2.5-A resolution. The structure is composed of two trigger-factor molecules related by a noncrystallographic two-fold symmetry axis. The monomer has an elongated shape and is folded into three domains: an N-terminal domain I that binds to the ribosome, a central domain II that contains PPIase activity, and a C-terminal domain III. The active site of the PPIase domain is occupied by a loop from domain III, suggesting that the PPIase activity of the protein could be regulated. The dimer interface is formed between domains I and III and contains residues of mixed properties. Further implications about dimerization, ribosome binding, and other functions of trigger factor are discussed.
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Affiliation(s)
- Anthony V Ludlam
- Department of Biological Chemistry, Medical School and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
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37
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Miot M, Betton JM. Protein quality control in the bacterial periplasm. Microb Cell Fact 2004; 3:4. [PMID: 15132751 PMCID: PMC420475 DOI: 10.1186/1475-2859-3-4] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2004] [Accepted: 05/07/2004] [Indexed: 11/16/2022] Open
Abstract
The proper functioning of extracytoplasmic proteins requires their export to, and productive folding in, the correct cellular compartment. All proteins in Escherichia coli are initially synthesized in the cytoplasm, then follow a pathway that depends upon their ultimate cellular destination. Many proteins destined for the periplasm are synthesized as precursors carrying an N-terminal signal sequence that directs them to the general secretion machinery at the inner membrane. After translocation and signal sequence cleavage, the newly exported mature proteins are folded and assembled in the periplasm. Maintaining quality control over these processes depends on chaperones, folding catalysts, and proteases. This article summarizes the general principles which control protein folding in the bacterial periplasm by focusing on the periplasmic maltose-binding protein.
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Affiliation(s)
- Marika Miot
- Unité Repliement et Modélisation des Protéines, Institut Pasteur, CNRS-URA2185, 28 rue du Dr Roux, 75754 Paris cedex 15, France
| | - Jean-Michel Betton
- Unité Repliement et Modélisation des Protéines, Institut Pasteur, CNRS-URA2185, 28 rue du Dr Roux, 75754 Paris cedex 15, France
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38
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Abstract
Spontaneous refolding of GdnHCl denatured bovine carbonic anhydrase II (BCA II) shows at least three phases: a burst phase, a fast phase, and a slow phase. The fast and slow phases are both controlled by proline isomerization. However, we find that in trigger factor (TF)-assisted BCA II folding, only the fast phase is catalyzed by wild-type TF, suggesting that certain proline residues are accessible in folding intermediates. The refolding yields of BCA II assisted by wild-type TF and TF mutants which lack PPIase activity are about the same, which provides further experimental evidence that the PPIase and chaperone activities of TF are independent. The binding of TF to folding intermediates during BCA II refolding was characterized by chemical crosslinking and Western blotting. A scheme for TF-assisted BCA II folding is proposed and the possible role of the TF dimer as a "binding" chaperone in vivo is discussed.
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Affiliation(s)
- Chuan-Peng Liu
- National laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, China
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39
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Saul FA, Arié JP, Vulliez-le Normand B, Kahn R, Betton JM, Bentley GA. Structural and functional studies of FkpA from Escherichia coli, a cis/trans peptidyl-prolyl isomerase with chaperone activity. J Mol Biol 2004; 335:595-608. [PMID: 14672666 DOI: 10.1016/j.jmb.2003.10.056] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The protein FkpA from the periplasm of Escherichia coli exhibits both cis/trans peptidyl-prolyl isomerase (PPIase) and chaperone activities. The crystal structure of the protein has been determined in three different forms: as the full-length native molecule, as a truncated form lacking the last 21 residues, and as the same truncated form in complex with the immunosuppressant ligand, FK506. FkpA is a dimeric molecule in which the 245-residue subunit is divided into two domains. The N-terminal domain includes three helices that are interlaced with those of the other subunit to provide all inter-subunit contacts maintaining the dimeric species. The C-terminal domain, which belongs to the FK506-binding protein (FKBP) family, binds the FK506 ligand. The overall form of the dimer is V-shaped, and the different crystal structures reveal a flexibility in the relative orientation of the two C-terminal domains located at the extremities of the V. The deletion mutant FkpNL, comprising the N-terminal domain only, exists in solution as a mixture of monomeric and dimeric species, and exhibits chaperone activity. By contrast, a deletion mutant comprising the C-terminal domain only is monomeric, and although it shows PPIase activity, it is devoid of chaperone function. These results suggest that the chaperone and catalytic activities reside in the N and C-terminal domains, respectively. Accordingly, the observed mobility of the C-terminal domains of the dimeric molecule could effectively adapt these two independent folding functions of FkpA to polypeptide substrates.
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Affiliation(s)
- F A Saul
- Unité d'Immunologie Structurale (C.N.R.S. U.R.A. 2185), Institut Pasteur, 25 rue du Dr Roux, 75724 Paris cedex 15, France
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40
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Köhler R, Fanghänel J, König B, Lüneberg E, Frosch M, Rahfeld JU, Hilgenfeld R, Fischer G, Hacker J, Steinert M. Biochemical and functional analyses of the Mip protein: influence of the N-terminal half and of peptidylprolyl isomerase activity on the virulence of Legionella pneumophila. Infect Immun 2003; 71:4389-97. [PMID: 12874317 PMCID: PMC166037 DOI: 10.1128/iai.71.8.4389-4397.2003] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The virulence factor Mip (macrophage infectivity potentiator) contributes to the intracellular survival of Legionella pneumophila, the causative agent of Legionnaires' disease. The protein consists of two domains that are connected via a very long alpha-helix (A. Riboldi-Tunnicliffe et al., Nat. Struct. Biol. 8:779-783, 2001). The fold of the C-terminal domain (residues 100 to 213) is closely related to human FK506-binding protein (FKBP12), and like FKBP12, Mip exhibits peptidylprolyl cis/trans isomerase (PPIase) activity. The alpha-helical N-terminal domain is responsible for the formation of very stable Mip homodimers. In order to determine the importance of the homodimeric state of Mip for its biochemical activities and for infectivity of Legionella, a truncated, monomeric Mip variant [Mip((77-213))] was overexpressed in Escherichia coli and characterized biochemically. In vitro isomerase activity assays revealed that the altered protein exhibits full isomerase activity towards peptide substrates. However, the deletion resulted in a dramatic loss in the efficiency of refolding of reduced and carboxy-methylated RNase T(1). By cis complementation of the Mip-negative mutant strain L. pneumophila JR32-2, we constructed the strain L. pneumophila JR32-2.4, which expresses an N-terminally truncated variant of Mip. Infection studies with these strains revealed that the N-terminal part and the dimerization of Mip but not its PPIase activity are necessary for full virulence in Acanthamoeba castellanii. Infection of guinea pigs showed that strains with dimerization-deficient Mip (JR32-2.4) or a very low PPIase activity (JR32-2.2) were significantly attenuated in the animal model. These results suggest a different role of the PPIase activity and the N-terminally mediated dimeric state of Mip in monocellular systems and during the infection of guinea pigs.
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Affiliation(s)
- Rolf Köhler
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, D-97070 Würzburg, Germany
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41
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Jacobs DM, Saxena K, Vogtherr M, Bernado P, Pons M, Fiebig KM. Peptide binding induces large scale changes in inter-domain mobility in human Pin1. J Biol Chem 2003; 278:26174-82. [PMID: 12686540 DOI: 10.1074/jbc.m300796200] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Pin1 is a peptidyl-prolyl cis/trans isomerase (PPIase) essential for cell cycle regulation. Pin1-catalyzed peptidyl-prolyl isomerization provides a key conformational switch to activate phosphorylation sites with the common phospho-Ser/Thr-Pro sequence motif. This motif is ubiquitously exploited in cellular response to a variety of signals. Pin1 is able to bind phospho-Ser/Thr-Pro-containing sequences at two different sites that compete for the same substrate. One binding site is located within the N-terminal WW domain, which is essential for protein targeting and localization. The other binding site is located in the C-terminal catalytic domain, which is structural homologous to the FK506-binding protein (FKBP) class of PPIases. A flexible linker of 12 residues connects the WW and catalytic domain. To characterize the structure and dynamics of full-length Pin1 in solution, high resolution NMR methods have been used to map the nature of interactions between the two domains of Pin1. In addition, the influence of target peptides on domain interactions has been investigated. The studies reveal a dynamic picture of the domain interactions. 15N spin relaxation data, differential chemical shift mapping, and residual dipolar coupling data indicate that Pin1 can either behave as two independent domains connected by the flexible linker or as a single intact domain with some amount of hinge bending motion depending on the sequence of the bound peptide. The functional importance of the modulation of relative domain flexibility in light of the multitude of interaction partners of Pin1 is discussed.
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Affiliation(s)
- Doris M Jacobs
- Institut für Organische Chemie und Chemische Biologie, Johann Wolfgang Goethe-Universität Frankfurt, Marie-Curie Strasse 11, 60439 Frankfurt, Germany.
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42
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Lyon WR, Caparon MG. Trigger factor-mediated prolyl isomerization influences maturation of the Streptococcus pyogenes cysteine protease. J Bacteriol 2003; 185:3661-7. [PMID: 12775704 PMCID: PMC156213 DOI: 10.1128/jb.185.12.3661-3667.2003] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Trigger factor, a ribosome-associated chaperone and peptidyl-prolyl cis-trans isomerase (PPIase), is essential for the secretion and maturation of the cysteine protease of the pathogenic gram-positive bacterium Streptococcus pyogenes. In the absence of trigger factor, the nascent protease polypeptide is not targeted to the secretory pathway. Some partial-function mutations restore targeting. However, the secreted protease does not efficiently mature into an enzymatically active form, suggesting that trigger factor has an additional role in protease biogenesis. Here, we show that, while not required for targeting, the PPIase activity of trigger factor is essential for maturation of the protease following its secretion from the bacterial cell. Site-specific mutations introduced into ropA, the gene which encodes trigger factor in S. pyogenes, produced mutant proteins deficient in PPIase activity. When these mutant alleles were used to replace the wild-type gene on the streptococcal chromosome, analysis of protease biogenesis revealed that, although the protease was secreted normally, it did not efficiently mature to an active form. Furthermore, mutation of a single proline residue in the protease prodomain suppressed the requirement for PPIase activity, suggesting that this residue is the target of trigger factor. These data support a model in which trigger factor-mediated prolyl isomerization influences the conformation of the prodomain, which in turn directs the protease into one of several alternative folding pathways.
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Affiliation(s)
- William R Lyon
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri 63110-1093, USA
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43
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Blaha G, Wilson DN, Stoller G, Fischer G, Willumeit R, Nierhaus KH. Localization of the trigger factor binding site on the ribosomal 50S subunit. J Mol Biol 2003; 326:887-97. [PMID: 12581648 DOI: 10.1016/s0022-2836(02)01436-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In Escherichia coli, protein folding is undertaken by three distinct sets of chaperones, the DnaK-DnaJ and GroEL-GroES systems and the trigger factor (TF). TF has been proposed to be the first chaperone to interact with the nascent polypeptide chain as it emerges from the tunnel of the 70S ribosome and thus probably plays an important role in co-translational protein folding. We have made complexes with deuterated ribosomes (50S subunits and 70S ribosomes) and protated TF and determined the TF binding site on the respective complexes using the neutron scattering technique of spin-contrast variation. Our data suggest that the TF binds in the form of a homodimer. On both the 50S subunit and the 70S ribosome, the TF position is in proximity to the tunnel exit site, near ribosomal proteins L23 and L29, located on the back of the 50S subunit. The positions deviate from one another, such that the position on the 70S ribosome is located slightly further from the tunnel than that determined for the 50S subunit alone. Nevertheless, from both determined positions interaction between TF and a short nascent chain of 57 amino acid residues would be plausible, compatible with a role for TF participation in co-translational protein folding.
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Affiliation(s)
- Gregor Blaha
- Max-Planck-Institut für Molekulare Genetik, AG Ribosomen, Ihnestrasse 73, D-14195 Berlin, Germany
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44
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Abstract
The trigger factor of Escherichia coli is a prolyl isomerase and a chaperone. It interacts with the ribosome and affects the folding of newly formed protein chains. Therefore, the dynamics of the interactions of trigger factor with the ribosome and with unfolded protein chains should be tailored for this function. Previously, we had found that binding of unfolded proteins to trigger factor is fast and that the lifetime of the complex between these two components is only about 100 ms. Here, we have labeled the trigger factor in its amino-terminal, ribosome-binding domain with a fluorescent dye and investigated how it interacts with the ribosome. We found that this association, as well as the dissociation of the complex, are rather slow processes. The average lifetime of the complex is about 30 seconds (at 20 degrees C). The strong differences in the dynamics of the interactions of trigger factor with the ribosome and with protein substrates might ensure that, on the one hand, trigger factor remains bound to the ribosome while a protein chain is being synthesized, and, on the other hand, allows it to scan the newly formed protein for prolyl bonds that need catalysis of isomerization.
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Affiliation(s)
- Raimund Maier
- Laboratorium für Biochemie, Universität Bayreuth, D-95440 Bayreuth, Germany
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Patzelt H, Kramer G, Rauch T, Schönfeld HJ, Bukau B, Deuerling E. Three-state equilibrium of Escherichia coli trigger factor. Biol Chem 2002; 383:1611-9. [PMID: 12452438 DOI: 10.1515/bc.2002.182] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Trigger Factor (TF) is the first chaperone that interacts with nascent chains of cytosolic proteins in Escherichia coli. Although its chaperone activity requires association with ribosomes, TF is present in vivo in a 2-3 fold molar excess over ribosomes and a fraction of it is not ribosome-associated after cell lysis. Here we show that TF follows a three-state equilibrium. Size exclusion chromatography, crosslinking and analytical ultracentrifugation revealed that uncomplexed TF dimerizes with an apparent Kd of 18 microM. Dimerization is mediated by the N-terminal ribosome binding domain and the C-terminal domain of TF, whereas the central peptidyl prolyl isomerase (PPlase) and substrate binding domain does not contribute to dimerization. Crosslinking experiments showed that TF is monomeric in its ribosome-associated state. Quantitative analysis of TF binding to ribosomes revealed a dissociation constant for the TF-ribosome complex of approximately 1.2 microM. From these data we estimate that in vivo most of the ribosomes are in complex with monomeric TF. Uncomplexed TF, however, is in a monomer-dimer equilibrium with approximately two thirds of TF existing in a dimeric state.
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Affiliation(s)
- Holger Patzelt
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, INF282, D-69120 Heidelberg, Germany
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46
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Affiliation(s)
- F X Schmid
- Biochemisches Laboratorium, Universität Bayreuth, D-95440 Bayreuth, Germany
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47
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Vogtherr M, Jacobs DM, Parac TN, Maurer M, Pahl A, Saxena K, Rüterjans H, Griesinger C, Fiebig KM. NMR solution structure and dynamics of the peptidyl-prolyl cis-trans isomerase domain of the trigger factor from Mycoplasma genitalium compared to FK506-binding protein. J Mol Biol 2002; 318:1097-115. [PMID: 12054805 DOI: 10.1016/s0022-2836(02)00112-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We have solved the solution structure of the peptidyl-prolyl cis-trans isomerase (PPIase) domain of the trigger factor from Mycoplasma genitalium by homo- and heteronuclear NMR spectroscopy. Our results lead to a well-defined structure with a backbone rmsd of 0.23 A. As predicted, the PPIase domain of the trigger factor adopts the FK506 binding protein (FKBP) fold. Furthermore, our NMR relaxation data indicate that the dynamic behavior of the trigger factor PPIase domain and of FKBP are similar. Structural variations when compared to FKBP exist in the flap region and within the bulges of strand 5 of the beta sheet. Although the active-site crevice is similar to that of FKBP, subtle steric variations in this region can explain why FK506 does not bind to the trigger factor. Sequence variability (27% identity) between trigger factor and FKBP results in significant differences in surface charge distribution and the absence of the first strand of the central beta sheet. Our data indicate, however, that this strand may be partially structured as "nascent" beta strand. This makes the trigger factor PPIase domain the most minimal representative of the FKBP like protein family of PPIases.
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Affiliation(s)
- Martin Vogtherr
- Institut für Organische Chemie der Universität Frankfurt, Marie-Curie-Str. 11, 60439 Frankfurt, Germany
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48
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Freedman RB, Klappa P, Ruddock LW. Protein disulfide isomerases exploit synergy between catalytic and specific binding domains. EMBO Rep 2002; 3:136-40. [PMID: 11839698 PMCID: PMC1083976 DOI: 10.1093/embo-reports/kvf035] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Protein disulfide isomerases (PDIs) catalyse the formation of native disulfide bonds in protein folding pathways. The key steps involve disulfide formation and isomerization in compact folding intermediates. The high-resolution structures of the a and b domains of PDI are now known, and the overall domain architecture of PDI and its homologues can be inferred. The isolated a and a' domains of PDI are good catalysts of simple thiol-disulfide interchange reactions but require additional domains to be effective as catalysts of the rate-limiting disulfide isomerizations in protein folding pathways. The b' domain of PDI has a specific binding site for peptides and its binding properties differ in specificity between members of the PDI family. A model of PDI function can be deduced in which the domains function synergically: the b' domain binds unstructured regions of polypeptide, while the a and a' domains catalyse the chemical isomerization steps.
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Affiliation(s)
- Robert B Freedman
- Department of Biosciences, University of Kent, Canterbury CT2 7NJ, UK.
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Webb HM, Ruddock LW, Marchant RJ, Jonas K, Klappa P. Interaction of the periplasmic peptidylprolyl cis-trans isomerase SurA with model peptides. The N-terminal region of SurA id essential and sufficient for peptide binding. J Biol Chem 2001; 276:45622-7. [PMID: 11546789 DOI: 10.1074/jbc.m107508200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One of the rate-limiting steps in protein folding has been shown to be the cis-trans isomerization of proline residues, which is catalyzed by a range of peptidylprolyl cis-trans isomerases. To characterize the interaction between model peptides and the periplasmic peptidylprolyl cis-trans isomerase SurA from E. coli, we employed a chemical cross-linking strategy that has been used previously to elucidate the interaction of substrates with other folding catalysts. The interaction between purified SurA and model peptides was significant in that it showed saturation and was abolished by denaturation of SurA; however the interaction was independent of the presence of proline residues in the model peptides. From results obtained by limited proteolysis we conclude that an N-terminal fragment of SurA, comprising 150 amino acids that do not contain the active sites involved in the peptidylprolyl cis-trans isomerization, is essential for the binding of peptides by SurA. This was confirmed by probing the interaction of the model peptide with the recombinant N-terminal fragment, expressed in Escherichia coli. Hence we propose that, similar to protein disulfide isomerase and other folding catalysts, SurA exhibits a modular architecture composed of a substrate binding domain and distinct catalytically active domains.
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Affiliation(s)
- H M Webb
- University of Kent, Canterbury CT2 7NJ, United Kingdom
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50
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Patzelt H, Rüdiger S, Brehmer D, Kramer G, Vorderwülbecke S, Schaffitzel E, Waitz A, Hesterkamp T, Dong L, Schneider-Mergener J, Bukau B, Deuerling E. Binding specificity of Escherichia coli trigger factor. Proc Natl Acad Sci U S A 2001; 98:14244-9. [PMID: 11724963 PMCID: PMC64667 DOI: 10.1073/pnas.261432298] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ribosome-associated chaperone trigger factor (TF) assists the folding of newly synthesized cytosolic proteins in Escherichia coli. Here, we determined the substrate specificity of TF by examining its binding to 2842 membrane-coupled 13meric peptides. The binding motif of TF was identified as a stretch of eight amino acids, enriched in basic and aromatic residues and with a positive net charge. Fluorescence spectroscopy verified that TF exhibited a comparable substrate specificity for peptides in solution. The affinity to peptides in solution was low, indicating that TF requires ribosome association to create high local concentrations of nascent polypeptide substrates for productive interaction in vivo. Binding to membrane-coupled peptides occurred through the central peptidyl-prolyl-cis/trans isomerase (PPIase) domain of TF, however, independently of prolyl residues. Crosslinking experiments showed that a TF fragment containing the PPIase domain linked to the ribosome via the N-terminal domain is sufficient for interaction with nascent polypeptide substrates. Homology modeling of the PPIase domain revealed a conserved FKBP(FK506-binding protein)-like binding pocket composed of exposed aromatic residues embedded in a groove with negative surface charge. The features of this groove complement well the determined substrate specificity of TF. Moreover, a mutation (E178V) in this putative substrate binding groove known to enhance PPIase activity also enhanced TF's association with a prolyl-free model peptide in solution and with nascent polypeptides. This result suggests that both prolyl-independent binding of peptide substrates and peptidyl-prolyl isomerization involve the same binding site.
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Affiliation(s)
- H Patzelt
- Institut für Biochemie und Molekularbiologie, Universität Freiburg, Hermann-Herder-Strasse 7, 79104 Freiburg, Germany
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