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A comprehensive review of signal peptides: Structure, roles, and applications. Eur J Cell Biol 2018; 97:422-441. [DOI: 10.1016/j.ejcb.2018.06.003] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 06/18/2018] [Accepted: 06/18/2018] [Indexed: 01/06/2023] Open
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2
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Garg SG, Gould SB. The Role of Charge in Protein Targeting Evolution. Trends Cell Biol 2016; 26:894-905. [PMID: 27524662 DOI: 10.1016/j.tcb.2016.07.001] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 06/28/2016] [Accepted: 07/11/2016] [Indexed: 12/31/2022]
Abstract
Two eukaryotic compartments are of endosymbiotic origin, the mitochondrion and plastid. These organelles need to import hundreds of proteins from the cytosol. The import machineries of both are of independent origin, but function in a similar fashion and recognize N-terminal targeting sequences that also share similarities. Targeting, however, is generally specific, even though plastid targeting evolved in the presence of established mitochondrial targeting. Here we review current advances on protein import into mitochondria and plastids from diverse eukaryotic lineages and highlight the impact of charged amino acids in targeting. Their presence or absence alone can determine localization, and comparisons across diverse eukaryotes, and their different types of mitochondria and plastids, uncover unexplored avenues of protein import research.
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Affiliation(s)
- Sriram G Garg
- Institute for Molecular Evolution, University of Düsseldorf, 40225 Düsseldorf, Germany
| | - Sven B Gould
- Institute for Molecular Evolution, University of Düsseldorf, 40225 Düsseldorf, Germany.
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3
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Hou B, Brüser T. The Tat-dependent protein translocation pathway. Biomol Concepts 2011; 2:507-23. [DOI: 10.1515/bmc.2011.040] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 08/05/2011] [Indexed: 11/15/2022] Open
Abstract
AbstractThe twin-arginine translocation (Tat) pathway is found in bacteria, archaea, and plant chloroplasts, where it is dedicated to the transmembrane transport of fully folded proteins. These proteins contain N-terminal signal peptides with a specific Tat-system binding motif that is recognized by the transport machinery. In contrast to other protein transport systems, the Tat system consists of multiple copies of only two or three usually small (∼8–30 kDa) membrane proteins that oligomerize to two large complexes that transiently interact during translocation. Only one of these complexes includes a polytopic membrane protein, TatC. The other complex consists of TatA. Tat systems of plants, proteobacteria, and several other phyla contain a third component, TatB. TatB is evolutionarily and structurally related to TatA and usually forms tight complexes with TatC. Minimal two-component Tat systems lacking TatB are found in many bacterial and archaeal phyla. They consist of a ‘bifunctional’ TatA that also covers TatB functionalities, and a TatC. Recent insights into the structure and interactions of the Tat proteins have various important implications.
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Affiliation(s)
- Bo Hou
- Institute of Microbiology, Leibniz University Hannover, Schneiderberg 50, D-30167 Hannover, Germany
| | - Thomas Brüser
- Institute of Microbiology, Leibniz University Hannover, Schneiderberg 50, D-30167 Hannover, Germany
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4
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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.
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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.
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Sec- and Tat-mediated protein secretion across the bacterial cytoplasmic membrane--distinct translocases and mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:1735-56. [PMID: 17935691 DOI: 10.1016/j.bbamem.2007.07.015] [Citation(s) in RCA: 340] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Revised: 07/23/2007] [Accepted: 07/24/2007] [Indexed: 11/20/2022]
Abstract
In bacteria, two major pathways exist to secrete proteins across the cytoplasmic membrane. The general Secretion route, termed Sec-pathway, catalyzes the transmembrane translocation of proteins in their unfolded conformation, whereupon they fold into their native structure at the trans-side of the membrane. The Twin-arginine translocation pathway, termed Tat-pathway, catalyses the translocation of secretory proteins in their folded state. Although the targeting signals that direct secretory proteins to these pathways show a high degree of similarity, the translocation mechanisms and translocases involved are vastly different.
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Rassow J, Pfanner N. Molecular chaperones and intracellular protein translocation. Rev Physiol Biochem Pharmacol 2006; 126:199-264. [PMID: 7886379 DOI: 10.1007/bfb0049777] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- J Rassow
- Biochemisches Institut, Universität Freiburg, Germany
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Musser SM, Theg SM. Characterization of the early steps of OE17 precursor transport by the thylakoid DeltapH/Tat machinery. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:2588-98. [PMID: 10785379 DOI: 10.1046/j.1432-1327.2000.01269.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In order to probe the structure and protein translocation function of the thylakoid Tat machinery, a 25-residue C-terminal extension containing a 13-residue in vivo biotinylation tag and a 6x His tag was added to a mutant precursor of the 17-kDa subunit of the oxygen-evolving complex to form pOE17(C)-BioHis. When avidin was attached to biotinylated precursor in situ, the precursor-avidin complex was neither imported nor did it form a membrane-spanning translocation intermediate. It did, however, competitively inhibit the translocation of unbiotinylated precursor with an apparent KI unaffected by avidin. It is shown that the precursor protein achieves a stable folded structure upon dilution from urea, suggesting that the avidin-induced inhibition of transport results from a folding-induced proximity of N-terminal and C-terminal domains. It is further demonstrated that the majority of precursor rapidly binds to the thylakoid membrane, remaining import competent and yet undissociable by high salt or high pH treatment at ice temperature. The membrane binding event is unaffected by avidin. Import kinetics reveal that nonproton motive force-driven transport steps make up a major fraction of the transport time. These observations suggest that the N-terminal presequence on the avidin-bound precursor is available for membrane binding and initial recognition by the transport machinery, but the attached avidin signals the machinery that the precursor is an incorrectly configured substrate and thus import is aborted. Consequently, the DeltapH/Tat machinery's proofreading mechanism must operate after precursor recognition but before the committed step in transport.
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Affiliation(s)
- S M Musser
- Section of Plant Biology, University of California, Davis, USA
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The biogenesis and assembly of photosynthetic proteins in thylakoid membranes1. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1411:21-85. [PMID: 10216153 DOI: 10.1016/s0005-2728(99)00043-2] [Citation(s) in RCA: 153] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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10
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Bradley PJ, Lahti CJ, Plümper E, Johnson PJ. Targeting and translocation of proteins into the hydrogenosome of the protist Trichomonas: similarities with mitochondrial protein import. EMBO J 1997; 16:3484-93. [PMID: 9218791 PMCID: PMC1169974 DOI: 10.1093/emboj/16.12.3484] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Trichomonads are early-diverging eukaryotes that lack both mitochondria and peroxisomes. They do contain a double membrane-bound organelle, called the hydrogenosome, that metabolizes pyruvate and produces ATP. To address the origin and biological nature of hydrogenosomes, we have established an in vitro protein import assay. Using purified hydrogenosomes and radiolabeled hydrogenosomal precursor ferredoxin (pFd), we demonstrate that protein import requires intact organelles, ATP and N-ethylmaleimide-sensitive cytosolic factors. Protein import is also affected by high concentrations of the protonophore, m-chlorophenylhydrazone (CCCP). Binding and translocation of pFd into hydrogenosomes requires the presence of an eight amino acid N-terminal presequence that is similar to presequences found on all examined hydrogenosomal proteins. Upon import, pFd is processed to a size consistent with cleavage of the presequence. Mutation of a conserved leucine at position 2 in the presequence to a glycine disrupts import of pFd into the organelle. Interestingly, a comparison of hydrogenosomal and mitochondrial protein presequences reveals striking similarities. These data indicate that mechanisms underlying protein targeting and biogenesis of hydrogenosomes and mitochondria are similar, consistent with the notion that these two organelles arose from a common endosymbiont.
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Affiliation(s)
- P J Bradley
- Department of Microbiology & Immunology, School of Medicine, Molecular Biology Institute, University of California, Los Angeles 90095, USA
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Abstract
Most major systems that transport proteins across a membrane share the following features: an amino-terminal transient signal sequence on the transported protein, a targeting system on the cis side of the membrane, a hetero-oligomeric transmembrane channel that is gated both across and within the plane of the membrane, a peripherally attached protein translocation motor that is powered by the hydrolysis of nucleoside triphosphate, and a protein folding system on the trans side of the membrane. These transport systems are divided into two families: export systems that export proteins out of the cytosol, and import systems that transport proteins into cytosol-like compartments.
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Affiliation(s)
- G Schatz
- Biozentrum der Universität Basel, Switzerland
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Nohara T, Nakai M, Goto A, Endo T. Isolation and characterization of the cDNA for pea chloroplast SecA. Evolutionary conservation of the bacterial-type SecA-dependent protein transport within chloroplasts. FEBS Lett 1995; 364:305-8. [PMID: 7758587 DOI: 10.1016/0014-5793(95)00415-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We report here the isolation of the cDNA for pea chloroplast SecA. Pea SecA encodes a polypeptide of 1,011 amino acids and shows high sequence similarity with cyanobacterial SecA. Pea SecA was synthesized as a larger precursor and was imported into isolated chloroplasts in vitro. The purified pea SecA, which was expressed in Escherichia coli cells, stimulated the in vitro import of the 33 kDa protein of the oxygen-evolving complex into thylakoids. These results indicate that higher plant chloroplasts contain a bacterial-type SecA protein-dependent system for the intraorganellar protein transport into thylakoids.
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Affiliation(s)
- T Nohara
- Department of Chemistry, Faculty of Science, Nagoya University Chikusa-ku, Japan
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Cohen Y, Yalovsky S, Nechushtai R. Integration and assembly of photosynthetic protein complexes in chloroplast thylakoid membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1241:1-30. [PMID: 7742345 DOI: 10.1016/0304-4157(94)00012-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- Y Cohen
- Department of Botany, Hebrew University of Jerusalem, Israel
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Reinbothe S, Reinbothe C, Runge S, Apel K. Enzymatic product formation impairs both the chloroplast receptor-binding function as well as translocation competence of the NADPH: protochlorophyllide oxidoreductase, a nuclear-encoded plastid precursor protein. J Cell Biol 1995; 129:299-308. [PMID: 7721935 PMCID: PMC2199915 DOI: 10.1083/jcb.129.2.299] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The key enzyme of chlorophyll biosynthesis in higher plants, the light-dependent NADPH:protochlorophyllide oxidoreductase (POR, EC 1.6.99.1), is a nuclear-encoded plastid protein. Its posttranslational transport into plastids of barley depends on the intraplastidic availability of one of its substrates, protochlorophyllide (PChlide). The precursor of POR (pPOR), synthesized from a corresponding full-length barley cDNA clone by coupling in vitro transcription and translation, is enzymatically active and converts PChlide to chlorophyllide (Chlide) in a light- and NADPH-dependent manner. Chlorophyllide formed catalytically remains tightly but noncovalently bound to the precursor protein and stabilizes a transport-incompetent conformation of pPOR. As shown by in vitro processing experiments, the chloroplast transit peptide in the Chlide-pPOR complex appears to be masked and thus is unable to physically interact with the outer plastid envelope membrane. In contrast, the chloroplast transit peptide in the naked pPOR (without its substrates and its product attached to it) and in the pPOR-substrate complexes, such as pPOR-PChlide or pPOR-PChlide-NADPH, seems to react independently of the mature region of the polypeptide, and thus is able to bind to the plastid envelope. When envelope-bound pPOR-PChlide-NADPH complexes were exposed to light during a short preincubation, the enzymatically produced Chlide slowed down the actual translocation step, giving rise to the sequential appearance of two partially processed translocation intermediates. However, ongoing translocation induced by feeding the chloroplasts delta-aminolevulinic acid, a precursor of PChlide, was able to override these two early blocks in translocation, suggesting that the plastid import machinery has a substantial capacity to denature a tightly folded, envelope-bound precursor protein. Together, our results show that pPOR with Chlide attached to it is impaired both in the ATP-dependent step of binding to a receptor protein component of the outer chloroplast envelope membrane, as well as in the PChlide-dependent step of precursor translocation.
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Affiliation(s)
- S Reinbothe
- Department of Genetics, Swiss Federal Institute of Technology Zurich (ETH), ETH-Zentrum
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15
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Abstract
Protein sorting signals provide good examples of peptides that can be studied both from a chemical and a biochemical perspective. Their simple designs and low degree of sequence conservation suggest that they are involved in rather non-specific peptide-lipid interactions, yet their ability to discriminate efficiently between the import machineries of different subcellular compartments rather points to the importance of peptide-receptor interactions. The study of protein sorting signals thus invites a cross-disciplinary approach.
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Affiliation(s)
- G von Heijne
- Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, Sweden
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Identification of the SecA protein homolog in pea chloroplasts and its possible involvement in thylakoidal protein transport. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)31698-3] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Madueño F, Bradshaw S, Gray J. The thylakoid-targeting domain of the chloroplast Rieske iron-sulfur protein is located in the N-terminal hydrophobic region of the mature protein. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)32462-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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18
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Henry R, Kapazoglou A, McCaffery M, Cline K. Differences between lumen targeting domains of chloroplast transit peptides determine pathway specificity for thylakoid transport. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)34041-3] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Post-translational modifications in plants (society for experimental biology seminar series 53). Trends Cell Biol 1994. [DOI: 10.1016/0962-8924(94)90015-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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