1
|
Bernal-Cabas M, Miethke M, Antelo-Varela M, Aguilar Suárez R, Neef J, Schön L, Gabarrini G, Otto A, Becher D, Wolf D, van Dijl JM. Functional association of the stress-responsive LiaH protein and the minimal TatAyCy protein translocase in Bacillus subtilis. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118719. [DOI: 10.1016/j.bbamcr.2020.118719] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/07/2020] [Accepted: 04/09/2020] [Indexed: 01/07/2023]
|
2
|
Abstract
The Tat pathway for protein translocation across bacterial membranes stands out for its selective handling of fully folded cargo proteins. In this review, we provide a comprehensive summary of our current understanding of the different known Tat components, their assembly into different complexes, and their specific roles in the protein translocation process. In particular, this overview focuses on the Gram-negative bacterium Escherichia coli and the Gram-positive bacterium Bacillus subtilis. Using these organisms as examples, we discuss structural features of Tat complexes alongside mechanistic models that allow for the Tat pathway's unique protein proofreading and transport capabilities. Finally, we highlight recent advances in exploiting the Tat pathway for biotechnological benefit, the production of high-value pharmaceutical proteins.
Collapse
|
3
|
Abstract
The twin-arginine protein translocation (Tat) system has been characterized in bacteria, archaea and the chloroplast thylakoidal membrane. This system is distinct from other protein transport systems with respect to two key features. Firstly, it accepts cargo proteins with an N-terminal signal peptide that carries the canonical twin-arginine motif, which is essential for transport. Second, the Tat system only accepts and translocates fully folded cargo proteins across the respective membrane. Here, we review the core essential features of folded protein transport via the bacterial Tat system, using the three-component TatABC system of Escherichia coli and the two-component TatAC systems of Bacillus subtilis as the main examples. In particular, we address features of twin-arginine signal peptides, the essential Tat components and how they assemble into different complexes, mechanistic features and energetics of Tat-dependent protein translocation, cytoplasmic chaperoning of Tat cargo proteins, and the remarkable proofreading capabilities of the Tat system. In doing so, we present the current state of our understanding of Tat-dependent protein translocation across biological membranes, which may serve as a lead for future investigations.
Collapse
Affiliation(s)
- Kelly M. Frain
- The School of Biosciences, University of Kent, Canterbury, CT2 7NZ UK
| | - Colin Robinson
- The School of Biosciences, University of Kent, Canterbury, CT2 7NZ UK
| | - Jan Maarten van Dijl
- Department of Medical Microbiology, University Medical Center Groningen, University of Groningen (UMCG), Hanzeplein 1, P.O. Box 30001, 9700 RB Groningen, The Netherlands
| |
Collapse
|
4
|
A Tat ménage à trois — The role of Bacillus subtilis TatAc in twin-arginine protein translocation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:2745-53. [DOI: 10.1016/j.bbamcr.2015.07.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 11/19/2022]
|
5
|
Affiliation(s)
- Ben C. Berks
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom;
| |
Collapse
|
6
|
Patel R, Vasilev C, Beck D, Monteferrante CG, van Dijl JM, Hunter CN, Smith C, Robinson C. A mutation leading to super-assembly of twin-arginine translocase (Tat) protein complexes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1978-86. [PMID: 24875903 DOI: 10.1016/j.bbamcr.2014.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 05/16/2014] [Accepted: 05/19/2014] [Indexed: 10/25/2022]
Abstract
The Tat system transports folded proteins across the bacterial plasma membrane. The mechanism is believed to involve coalescence of a TatC-containing unit with a separate TatA complex, but the full translocation complex has never been visualised and the assembly process is poorly defined. We report the analysis of the Bacillus subtilis TatAyCy system, which occurs as separate TatAyCy and TatAy complexes at steady state, using single-particle electron microscopy (EM) and advanced atomic force microscopy (AFM) approaches. We show that a P2A mutation in the TatAy subunit leads to apparent super-assembly of Tat complexes. Purification of TatCy-containing complexes leads to a large increase in the TatA:TatC ratio, suggesting that TatAy(P2A) complexes may have attached to the TatAyCy complex. EM and AFM analyses show that the wild-type TatAyCy complex purifies as roughly spherical complexes of 9-16nm diameter, whereas the P2A mutation leads to accumulation of large (up to 500nm long) fibrils that are chains of numerous complexes. Time lapsed AFM imaging, recorded on fibrils under liquid, shows that they adopt a variety of tightly curved conformations, with radii of curvature of 10-12nm comparable to the size of single TatAy(P2A) complexes. The combined data indicate that the mutation leads to super-assembly of TatAy(P2A) complexes and we propose that an individual TatAy(P2A) complex assembles initially with a TatAy(P2A)Cy complex, after which further TatAy(P2A) complexes attach to each other. The data further suggest that the N-terminal extracytoplasmic domain of TatAy plays an essential role in Tat complex interactions.
Collapse
Affiliation(s)
- Roshani Patel
- School of Life Sciences, Gibbet Hill Campus, The University of Warwick, Coventry CV4 7AL, UK
| | - Cvetelin Vasilev
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Daniel Beck
- School of Life Sciences, Gibbet Hill Campus, The University of Warwick, Coventry CV4 7AL, UK
| | - Carmine G Monteferrante
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Jan Maarten van Dijl
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Corinne Smith
- School of Life Sciences, Gibbet Hill Campus, The University of Warwick, Coventry CV4 7AL, UK
| | - Colin Robinson
- Centre for Molecular Processing, School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK.
| |
Collapse
|
7
|
Goosens VJ, Monteferrante CG, van Dijl JM. The Tat system of Gram-positive bacteria. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:1698-706. [PMID: 24140208 DOI: 10.1016/j.bbamcr.2013.10.008] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Revised: 10/08/2013] [Accepted: 10/08/2013] [Indexed: 10/26/2022]
Abstract
The twin-arginine protein translocation (Tat) system has a unique ability to translocate folded and co-factor-containing proteins across lipid bilayers. The Tat pathway is present in bacteria, archaea and in the thylakoid membranes of chloroplasts and, depending on the organism and environmental conditions, it can be deemed important for cell survival, virulence or bioproduction. This review provides an overview of the current understanding of the Tat system with specific focus on Gram-positive bacteria. The 'universal minimal Tat system' is composed of a TatA and a TatC protein. However, this pathway is more commonly composed of two TatA-like proteins and one TatC protein. Often the TatA-like proteins have diverged to have two different functions and, in this case, the second TatA-like protein is usually referred to as TatB. The correct folding and/or incorporation of co-factors are requirements for translocation, and the known quality control mechanisms are examined in this review. A number of examples of crosstalk between the Tat system and other protein transport systems, such as the Sec-YidC translocon and signal peptidases or sheddases are also discussed. Further, an overview of specific Gram-positive bacterial Tat systems found in monoderm and diderm species is detailed. Altogether, this review highlights the unique features of Gram-positive bacterial Tat systems and pinpoints key questions that remain to be addressed in future research. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
Collapse
Affiliation(s)
- Vivianne J Goosens
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, 9700 RB Groningen, The Netherlands
| | - Carmine G Monteferrante
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, 9700 RB Groningen, The Netherlands
| | - Jan Maarten van Dijl
- Department of Medical Microbiology, University of Groningen, University Medical Center Groningen, Hanzeplein 1, P.O. Box 30001, 9700 RB Groningen, The Netherlands.
| |
Collapse
|
8
|
Palmer T, Berks BC. The twin-arginine translocation (Tat) protein export pathway. Nat Rev Microbiol 2012; 10:483-96. [PMID: 22683878 DOI: 10.1038/nrmicro2814] [Citation(s) in RCA: 359] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The twin-arginine translocation (Tat) protein export system is present in the cytoplasmic membranes of most bacteria and archaea and has the highly unusual property of transporting fully folded proteins. The system must therefore provide a transmembrane pathway that is large enough to allow the passage of structured macromolecular substrates of different sizes but that maintains the impermeability of the membrane to ions. In the Gram-negative bacterium Escherichia coli, this complex task can be achieved by using only three small membrane proteins: TatA, TatB and TatC. In this Review, we summarize recent advances in our understanding of how this remarkable machine operates.
Collapse
Affiliation(s)
- Tracy Palmer
- Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
| | | |
Collapse
|
9
|
Albiniak AM, Baglieri J, Robinson C. Targeting of lumenal proteins across the thylakoid membrane. JOURNAL OF EXPERIMENTAL BOTANY 2012; 63:1689-98. [PMID: 22275386 DOI: 10.1093/jxb/err444] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The biogenesis of the plant thylakoid network is an enormously complex process in terms of protein targeting. The membrane system contains a large number of proteins, some of which are synthesized within the organelle, while many others are imported from the cytosol. Studies in recent years have shown that the targeting of imported proteins into and across the thylakoid membrane is particularly complex, with four different targeting pathways identified to date. Two of these are used to target membrane proteins: a signal recognition particle (SRP)-dependent pathway and a highly unusual pathway that appears to require none of the known targeting apparatus. Two further pathways are used to translocate lumenal proteins across the thylakoid membrane from the stroma and, again, the two pathways differ dramatically from each other. One is a Sec-type pathway, in which ATP hydrolysis by SecA drives the transport of the substrate protein through the membrane in an unfolded conformation. The other is the twin-arginine translocation (Tat) pathway, where substrate proteins are transported in a folded state using a unique mechanism that harnesses the proton motive force across the thylakoid membrane. This article reviews progress in studies on the targeting of lumenal proteins, with reference to the mechanisms involved, their evolution from endosymbiotic progenitors of the chloroplast, and possible elements of regulation.
Collapse
Affiliation(s)
- Anna M Albiniak
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | | | | |
Collapse
|
10
|
van der Ploeg R, Barnett JP, Vasisht N, Goosens VJ, Pöther DC, Robinson C, van Dijl JM. Salt sensitivity of minimal twin arginine translocases. J Biol Chem 2011; 286:43759-43770. [PMID: 22041895 DOI: 10.1074/jbc.m111.243824] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacterial twin arginine translocation (Tat) pathways have evolved to facilitate transport of folded proteins across membranes. Gram-negative bacteria contain a TatABC translocase composed of three subunits named TatA, TatB, and TatC. In contrast, the Tat translocases of most Gram-positive bacteria consist of only TatA and TatC subunits. In these minimal TatAC translocases, a bifunctional TatA subunit fulfils the roles of both TatA and TatB. Here we have probed the importance of conserved residues in the bifunctional TatAy subunit of Bacillus subtilis by site-specific mutagenesis. A set of engineered TatAy proteins with mutations in the cytoplasmic hinge and amphipathic helix regions were found to be inactive in protein translocation under standard growth conditions for B. subtilis or when heterologously expressed in Escherichia coli. Nevertheless, these mutated TatAy proteins did assemble into TatAy and TatAyCy complexes, and they facilitated membrane association of twin arginine precursor proteins in E. coli. Interestingly, most of the mutated TatAyCy translocases were salt-sensitive in B. subtilis. Similarly, the TatAC translocases of Bacillus cereus and Staphylococcus aureus were salt-sensitive when expressed in B. subtilis. Taken together, our present observations imply that salt-sensitive electrostatic interactions have critical roles in the preprotein translocation activity of certain TatAC type translocases from Gram-positive bacteria.
Collapse
Affiliation(s)
- René van der Ploeg
- Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, 9700 RB Groningen, The Netherlands
| | - James P Barnett
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Nishi Vasisht
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Vivianne J Goosens
- Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, 9700 RB Groningen, The Netherlands
| | - Dierk C Pöther
- Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, 9700 RB Groningen, The Netherlands
| | - Colin Robinson
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom
| | - Jan Maarten van Dijl
- Department of Medical Microbiology, University Medical Center Groningen and University of Groningen, 9700 RB Groningen, The Netherlands.
| |
Collapse
|
11
|
Barnett JP, Robinson C, Scanlan DJ, Blindauer CA. The Tat protein export pathway and its role in cyanobacterial metalloprotein biosynthesis. FEMS Microbiol Lett 2011; 325:1-9. [PMID: 22092855 DOI: 10.1111/j.1574-6968.2011.02391.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 08/11/2011] [Accepted: 08/16/2011] [Indexed: 11/27/2022] Open
Abstract
The Tat pathway is a common protein translocation system that is found in the bacterial cytoplasmic membrane, as well as in the cyanobacterial and plant thylakoid membranes. It is unusual in that the Tat pathway transports fully folded, often metal cofactor-containing proteins across these membranes. In bacteria, the Tat pathway plays an important role in the biosynthesis of noncytoplasmic metalloproteins. By compartmentalizing protein folding to the cytoplasm, the potentially aberrant binding of non-native metal ions to periplasmic proteins is avoided. To date, most of our understanding of Tat function has been obtained from studies using Escherichia coli as a model organism but cyanobacteria have an extra layer of complexity with proteins targeted to both the cytoplasmic and thylakoid membranes. We examine our current understanding of the Tat pathway in cyanobacteria and its role in metalloprotein biosynthesis.
Collapse
Affiliation(s)
- James P Barnett
- Department of Chemistry, University of Warwick, Coventry, UK.
| | | | | | | |
Collapse
|