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Stiller LM, Galinski EA, Witt EMHJ. Engineering the Salt-Inducible Ectoine Promoter Region of Halomonas elongata for Protein Expression in a Unique Stabilizing Environment. Genes (Basel) 2018; 9:genes9040184. [PMID: 29597294 PMCID: PMC5924526 DOI: 10.3390/genes9040184] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 03/19/2018] [Accepted: 03/21/2018] [Indexed: 01/11/2023] Open
Abstract
It has been firmly established that organic osmolytes (compatible solutes) of halophilic Bacteria and Archaea have positive effects on conformation and activity of proteins, and may therefore improve their functional production. In particular, the amino acid derivative ectoine is known for its conformational stabilization, aggregation suppression, and radical protection properties. The natural producer and industrial production strain Halomonas elongata accumulates ectoine in the cytoplasm, and as a result offers a unique stabilizing environment for recombinant proteins. For the construction of broad hoast range vector systems with fluorescent reporter proteins, we chose the salt-inducible promoter region of the ectoine gene cluster (promA). A closer inspection of the genetic background revealed that its combination of sigma 38 (σ38) and sigma 70 (σ70) promoters was followed by a weak ribosomal binding site (RBS). This inspired a systematic approach for the construction of a promA-based vector series with a synthetic RBS region using the RBS Calculator v2.0, which resulted in a greatly improved salt-dependent expression-even in a deletion construct lacking the σ38 promoter. To expand the application range of this expression system, we looked further into the possible export of recombinant proteins into the periplasm. Both sec and tat leader sequences from H. elongata proved to be suitable for directed periplasmic transport into an extreme environment of freely selectable ionic strength.
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Affiliation(s)
- Lisa M Stiller
- Institute of Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms University Bonn, 53115 Bonn, Germany.
| | - Erwin A Galinski
- Institute of Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms University Bonn, 53115 Bonn, Germany.
| | - Elisabeth M H J Witt
- Institute of Microbiology and Biotechnology, Rheinische Friedrich-Wilhelms University Bonn, 53115 Bonn, Germany.
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2
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Nishimura K, Kato Y, Sakamoto W. Chloroplast Proteases: Updates on Proteolysis within and across Suborganellar Compartments. PLANT PHYSIOLOGY 2016; 171:2280-93. [PMID: 27288365 PMCID: PMC4972267 DOI: 10.1104/pp.16.00330] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Indexed: 05/08/2023]
Abstract
Chloroplasts originated from the endosymbiosis of ancestral cyanobacteria and maintain transcription and translation machineries for around 100 proteins. Most endosymbiont genes, however, have been transferred to the host nucleus, and the majority of the chloroplast proteome is composed of nucleus-encoded proteins that are biosynthesized in the cytosol and then imported into chloroplasts. How chloroplasts and the nucleus communicate to control the plastid proteome remains an important question. Protein-degrading machineries play key roles in chloroplast proteome biogenesis, remodeling, and maintenance. Research in the past few decades has revealed more than 20 chloroplast proteases, which are localized to specific suborganellar locations. In particular, two energy-dependent processive proteases of bacterial origin, Clp and FtsH, are central to protein homeostasis. Processing endopeptidases such as stromal processing peptidase and thylakoidal processing peptidase are involved in the maturation of precursor proteins imported into chloroplasts by cleaving off the amino-terminal transit peptides. Presequence peptidases and organellar oligopeptidase subsequently degrade the cleaved targeting peptides. Recent findings have indicated that not only intraplastidic but also extraplastidic processive protein-degrading systems participate in the regulation and quality control of protein translocation across the envelopes. In this review, we summarize current knowledge of the major chloroplast proteases in terms of type, suborganellar localization, and diversification. We present details of these degradation processes as case studies according to suborganellar compartment (envelope, stroma, and thylakoids). Key questions and future directions in this field are discussed.
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Affiliation(s)
- Kenji Nishimura
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan
| | - Yusuke Kato
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan
| | - Wataru Sakamoto
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan
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3
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Midorikawa T, Inoue K. Multiple fates of non-mature lumenal proteins in thylakoids. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 76:73-86. [PMID: 23802992 DOI: 10.1111/tpj.12273] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 06/18/2013] [Accepted: 06/24/2013] [Indexed: 06/02/2023]
Abstract
Most proteins found in the thylakoid lumen are synthesized in the cytosol with an N-terminal extension consisting of transient signals for chloroplast import and thylakoid transfer in tandem. The thylakoid-transfer signal is required for protein sorting from the stroma to thylakoids, mainly via the cpSEC or cpTAT pathway, and is removed by the thylakoidal processing peptidase in the lumen. An Arabidopsis mutant lacking one of the thylakoidal processing peptidase homologs, Plsp1, contains plastids with anomalous thylakoids and is seedling-lethal. Furthermore, the mutant plastids accumulate two cpSEC substrates (PsbO and PetE) and one cpTAT substrate (PsbP) as intermediate forms. These properties of plsp1-null plastids suggest that complete maturation of lumenal proteins is a critical step for proper thylakoid assembly. Here we tested the effects of inhibition of thylakoid-transfer signal removal on protein targeting and accumulation by examining the localization of non-mature lumenal proteins in the Arabidopsis plsp1-null mutant and performing a protein import assay using pea chloroplasts. In plsp1-null plastids, the two cpSEC substrates were shown to be tightly associated with the membrane, while non-mature PsbP was found in the stroma. The import assay revealed that inhibition of thylakoid-transfer signal removal did not disrupt cpSEC- and cpTAT-dependent translocation, but prevented release of proteins from the membrane. Interestingly, non-mature PetE2 was quickly degraded under light, and unprocessed PsbO1 and PsbP1 were found in a 440-kDa complex and as a monomer, respectively. These results indicate that the cpTAT pathway may be disrupted in the plsp1-null mutant, and that there are multiple mechanisms to control unprocessed lumenal proteins in thylakoids.
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Affiliation(s)
- Takafumi Midorikawa
- Department of Plant Sciences, University of California, 1 Shields Avenue, Davis, CA, 95616, USA
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4
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Kudva R, Denks K, Kuhn P, Vogt A, Müller M, Koch HG. Protein translocation across the inner membrane of Gram-negative bacteria: the Sec and Tat dependent protein transport pathways. Res Microbiol 2013; 164:505-34. [DOI: 10.1016/j.resmic.2013.03.016] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 03/11/2013] [Indexed: 11/28/2022]
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5
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Transmembrane insertion of twin-arginine signal peptides is driven by TatC and regulated by TatB. Nat Commun 2013; 3:1311. [PMID: 23250441 PMCID: PMC3538955 DOI: 10.1038/ncomms2308] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 11/15/2012] [Indexed: 12/03/2022] Open
Abstract
The twin-arginine translocation (Tat) pathway of bacteria and plant chloroplasts mediates the transmembrane transport of folded proteins, which harbour signal sequences with a conserved twin-arginine motif. Many Tat translocases comprise the three membrane proteins TatA, TatB and TatC. TatC was previously shown to be involved in recognizing twin-arginine signal peptides. Here we show that beyond recognition, TatC mediates the transmembrane insertion of a twin-arginine signal sequence, thereby translocating the signal sequence cleavage site across the bilayer. In the absence of TatB, this can lead to the removal of the signal sequence even from a translocation-incompetent substrate. Hence interaction of twin-arginine signal peptides with TatB counteracts their premature cleavage uncoupled from translocation. This capacity of TatB is not shared by the homologous TatA protein. Collectively our results suggest that TatC is an insertase for twin-arginine signal peptides and that translocation-proficient signal sequence recognition requires the concerted action of TatC and TatB. TatA, B and C act together to translocate folded proteins across bacterial and chloroplast membranes, however the precise mechanism remains unclear. Fröbel and colleagues discover that TatC has unforeseen membrane insertase activity, while TatB prevents premature cleavage before translocation.
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6
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Endow JK, Inoue K. Stable complex formation of thylakoidal processing peptidase and PGRL1. FEBS Lett 2013; 587:2226-31. [DOI: 10.1016/j.febslet.2013.05.050] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 05/10/2013] [Accepted: 05/16/2013] [Indexed: 12/19/2022]
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7
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Ramasamy S, Abrol R, Suloway CJ, Clemons WM. The glove-like structure of the conserved membrane protein TatC provides insight into signal sequence recognition in twin-arginine translocation. Structure 2013; 21:777-88. [PMID: 23583035 PMCID: PMC3653977 DOI: 10.1016/j.str.2013.03.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 02/14/2013] [Accepted: 03/07/2013] [Indexed: 11/23/2022]
Abstract
In bacteria, two signal-sequence-dependent secretion pathways translocate proteins across the cytoplasmic membrane. Although the mechanism of the ubiquitous general secretory pathway is becoming well understood, that of the twin-arginine translocation pathway, responsible for translocation of folded proteins across the bilayer, is more mysterious. TatC, the largest and most conserved of three integral membrane components, provides the initial binding site of the signal sequence prior to pore assembly. Here, we present two crystal structures of TatC from the thermophilic bacteria Aquifex aeolicus at 4.0 Å and 6.8 Å resolution. The membrane architecture of TatC includes a glove-shaped structure with a lipid-exposed pocket predicted by molecular dynamics to distort the membrane. Correlating the biochemical literature to these results suggests that the signal sequence binds in this pocket, leading to structural changes that facilitate higher order assemblies.
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Affiliation(s)
| | - Ravinder Abrol
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Christian J.M. Suloway
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - William M. Clemons
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA
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8
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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.
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Affiliation(s)
- Tracy Palmer
- Division of Molecular Microbiology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK.
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9
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Fröbel J, Rose P, Müller M. Twin-arginine-dependent translocation of folded proteins. Philos Trans R Soc Lond B Biol Sci 2012; 367:1029-46. [PMID: 22411976 PMCID: PMC3297433 DOI: 10.1098/rstb.2011.0202] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Twin-arginine translocation (Tat) denotes a protein transport pathway in bacteria, archaea and plant chloroplasts, which is specific for precursor proteins harbouring a characteristic twin-arginine pair in their signal sequences. Many Tat substrates receive cofactors and fold prior to translocation. For a subset of them, proofreading chaperones coordinate maturation and membrane-targeting. Tat translocases comprise two kinds of membrane proteins, a hexahelical TatC-type protein and one or two members of the single-spanning TatA protein family, called TatA and TatB. TatC- and TatA-type proteins form homo- and hetero-oligomeric complexes. The subunits of TatABC translocases are predominantly recovered from two separate complexes, a TatBC complex that might contain some TatA, and a homomeric TatA complex. TatB and TatC coordinately recognize twin-arginine signal peptides and accommodate them in membrane-embedded binding pockets. Advanced binding of the signal sequence to the Tat translocase requires the proton-motive force (PMF) across the membranes and might involve a first recruitment of TatA. When targeted in this manner, folded twin-arginine precursors induce homo-oligomerization of TatB and TatA. Ultimately, this leads to the formation of a transmembrane protein conduit that possibly consists of a pore-like TatA structure. The translocation step again is dependent on the PMF.
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Affiliation(s)
- Julia Fröbel
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, Stefan-Meier-Strasse 17, 79104 Freiburg, Germany
- Faculty of Biology, University of Freiburg, Schänzle-Strasse 1, 79104 Freiburg, Germany
| | - Patrick Rose
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, Stefan-Meier-Strasse 17, 79104 Freiburg, Germany
- Faculty of Biology, University of Freiburg, Schänzle-Strasse 1, 79104 Freiburg, Germany
| | - Matthias Müller
- Institute of Biochemistry and Molecular Biology, ZBMZ, University of Freiburg, Stefan-Meier-Strasse 17, 79104 Freiburg, Germany
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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.
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Affiliation(s)
- Anna M Albiniak
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
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11
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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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12
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Abstract
Proteins that reside partially or completely outside the bacterial cytoplasm require specialized pathways to facilitate their localization. Globular proteins that function in the periplasm must be translocated across the hydrophobic barrier of the inner membrane. While the Sec pathway transports proteins in a predominantly unfolded conformation, the Tat pathway exports folded protein substrates. Protein transport by the Tat machinery is powered solely by the transmembrane proton gradient, and there is no requirement for nucleotide triphosphate hydrolysis. Proteins are targeted to the Tat machinery by N-terminal signal peptides that contain a consensus twin arginine motif. In Escherichia coli and Salmonella there are approximately thirty proteins with twin arginine signal peptides that are transported by the Tat pathway. The majority of these bind complex redox cofactors such as iron sulfur clusters or the molybdopterin cofactor. Here we describe what is known about Tat substrates in E. coli and Salmonella, the function and mechanism of Tat protein export, and how the cofactor insertion step is coordinated to ensure that only correctly assembled substrates are targeted to the Tat machinery.
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13
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Shipman-Roston RL, Ruppel NJ, Damoc C, Phinney BS, Inoue K. The significance of protein maturation by plastidic type I signal peptidase 1 for thylakoid development in Arabidopsis chloroplasts. PLANT PHYSIOLOGY 2010; 152:1297-308. [PMID: 20097790 PMCID: PMC2832241 DOI: 10.1104/pp.109.151977] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2009] [Accepted: 01/19/2010] [Indexed: 05/20/2023]
Abstract
Thylakoids are the chloroplast internal membrane systems that house light-harvesting and electron transport reactions. Despite the important functions and well-studied constituents of thylakoids, the molecular mechanism of their development remains largely elusive. A recent genetic study has demonstrated that plastidic type I signal peptidase 1 (Plsp1) is vital for proper thylakoid development in Arabidopsis (Arabidopsis thaliana) chloroplasts. Plsp1 was also shown to be necessary for processing of an envelope protein, Toc75, and a thylakoid lumenal protein, OE33; however, the relevance of the protein maturation in both of the two distinct subcompartments for proper chloroplast development remained unknown. Here, we conducted an extensive analysis of the plsp1-null mutant to address the significance of lumenal protein maturation in thylakoid development. Plastids that lack Plsp1 were found to accumulate vesicles of variable sizes in the stroma. Analyses of the mutant plastids revealed that the lack of Plsp1 causes a reduction in accumulation of thylakoid proteins and that Plsp1 is involved in maturation of two additional lumenal proteins, OE23 and plastocyanin. Further immunoblotting and electron microscopy immunolocalization studies showed that OE33 associates with the stromal vesicles of the mutant plastids. Finally, we used a genetic complementation system to demonstrate that accumulation of improperly processed forms of Toc75 in the plastid envelope does not disrupt normal plant development. These results suggest that proper maturation of lumenal proteins may be a key process for correct assembly of thylakoids.
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14
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Impaired plant growth and development caused by human immunodeficiency virus type 1 Tat. Transgenic Res 2010; 19:903-13. [PMID: 20087655 DOI: 10.1007/s11248-010-9360-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Accepted: 12/31/2009] [Indexed: 10/20/2022]
Abstract
Previous attempts to express the human immunodeficiency virus 1 (HIV-1) Tat (trans-activator of transcription) protein in plants resulted in a number of physiological abnormalities, such as stunted growth and absence of seed formation, that could not be explained. In the study reported here, we expressed Tat in tomato and observed phenotypic abnormalities, including stunted growth, absence of root formation, chlorosis, and plant death, as a result of reduced cytokinin levels. These reduced levels were ascribed to a differentially expressed CKO35 in Tat-bombarded tomato. Of the two CKO isoforms that are naturally expressed in tomato, CKO43 and CKO37, only the expression of CKO37 was affected by Tat. Our analysis of the Tat confirmed that the Arg-rich and RGD motifs of Tat have functional relevance in tomato and that independent mutations at these motifs caused inhibition of the differentially expressed CKO isoform and the extracellular secretion of the Tat protein, respectively, in our Tat-bombarded tomato samples.
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15
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Vladimirou E, Li M, Aldridge CP, Frigerio L, Kirkilionis M, Robinson C. Diffusion of a membrane protein, Tat subunit Hcf106, is highly restricted within the chloroplast thylakoid network. FEBS Lett 2009; 583:3690-6. [PMID: 19854178 DOI: 10.1016/j.febslet.2009.10.057] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2009] [Revised: 10/16/2009] [Accepted: 10/19/2009] [Indexed: 11/17/2022]
Abstract
The thylakoid membrane forms stacked thylakoids interconnected by 'stromal' lamellae. Little is known about the mobility of proteins within this system. We studied a stromal lamellae protein, Hcf106, by targeting an Hcf106-GFP fusion protein to the thylakoids and photobleaching. We find that even small regions fail to recover Hcf106-GFP fluorescence over periods of up to 3 min after photobleaching. The protein is thus either immobile within the thylakoid membrane, or its diffusion is tightly restricted within distinct regions. Autofluorescence from the photosystem II light-harvesting complex in the granal stacks likewise fails to recover. Integral membrane proteins within both the stromal and granal membranes are therefore highly constrained, possibly forming 'microdomains' that are sharply separated.
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Affiliation(s)
- Elina Vladimirou
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
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16
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Panahandeh S, Maurer C, Moser M, DeLisa MP, Müller M. Following the path of a twin-arginine precursor along the TatABC translocase of Escherichia coli. J Biol Chem 2008; 283:33267-75. [PMID: 18836181 DOI: 10.1074/jbc.m804225200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The twin-arginine translocation (Tat) machinery present in bacterial and thylakoidal membranes is able to transport fully folded proteins. Consistent with previous in vivo data, we show that the model Tat substrate TorA-PhoA is translocated by the TatABC translocase of Escherichia coli inner membrane vesicles, only if the PhoA moiety was allowed to fold by disulfide bond formation. Although even unfolded TorA-PhoA was found to physically associate with the Tat translocase of the vesicles, site-specific cross-linking revealed a perturbed interaction of the signal sequence of unfolded TorA-PhoA with the TatBC receptor site. Some of the folded TorA-PhoA precursor accumulated in a partially protease-protected membrane environment, from where it could be translocated into the lumen of the vesicles upon re-installation of an H+-gradient. Translocation arrest occurred in immediate vicinity to TatA. Consistent with a neighborhood to TatA, TorA-PhoA remained protease-resistant in the presence of detergents that are known to preserve the oligomeric structures of TatA. Moreover, entry of TorA-PhoA to the protease-protected environment strictly required the presence of TatA. Collectively, our results are consistent with some degree of quality control by TatBC and a recruitment of TatA to a folded substrate that has functionally engaged the twin-arginine translocase.
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Affiliation(s)
- Sascha Panahandeh
- Institut für Biochemie und Molekularbiologie, ZBMZ, Freiburg, Germany
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17
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Zhang C, Liu Y, Sun X, Qian W, Zhang D, Qiu B. Characterization of a specific interaction between IP-L, a tobacco protein localized in the thylakoid membranes, and Tomato mosaic virus coat protein. Biochem Biophys Res Commun 2008; 374:253-7. [PMID: 18625203 DOI: 10.1016/j.bbrc.2008.07.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Accepted: 07/03/2008] [Indexed: 11/25/2022]
Abstract
We previously demonstrated a specific interaction between Tomato mosaic virus (ToMV) coat protein (CP) and a tobacco protein designated IP-L that may be involved in the long-distance movement of ToMV. Here, using the yeast two-hybrid system and GST pull-down assay, we demonstrated that the N-terminal helical region (residues 3-18) of IP-L is required for the interaction, while two alpha-helical domains (residues 21-31 and 142-147) of ToMV CP are involved. Furthermore, using immunoblotting, we showed that both of the IP-L and the majority of ToMV CP are co-localized in the chloroplast thylakoid membranes. These results provide further evidence for the association between tobamovirus CPs and thylakoid membrane components, which has been shown to be involved in chlorosis formation during viral infection, and indicate that the interaction between ToMV CP and IP-L may affect chloroplast function and stability and thus leading to chlorosis.
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Affiliation(s)
- Chaozheng Zhang
- Center for Agricultural Biotechnology, Institute of Microbiology, Chinese Academy of Sciences, Datun Road, Chaoyang District, Beijing 100101, China
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18
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Puthiyaveetil S, Kavanagh TA, Cain P, Sullivan JA, Newell CA, Gray JC, Robinson C, van der Giezen M, Rogers MB, Allen JF. The ancestral symbiont sensor kinase CSK links photosynthesis with gene expression in chloroplasts. Proc Natl Acad Sci U S A 2008; 105:10061-6. [PMID: 18632566 PMCID: PMC2474565 DOI: 10.1073/pnas.0803928105] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Indexed: 11/18/2022] Open
Abstract
We describe a novel, typically prokaryotic, sensor kinase in chloroplasts of green plants. The gene for this chloroplast sensor kinase (CSK) is found in cyanobacteria, prokaryotes from which chloroplasts evolved. The CSK gene has moved, during evolution, from the ancestral chloroplast to the nuclear genomes of eukaryotic algae and green plants. The CSK protein is now synthesised in the cytosol of photosynthetic eukaryotes and imported into their chloroplasts as a protein precursor. In the model higher plant Arabidopsis thaliana, CSK is autophosphorylated and required for control of transcription of chloroplast genes by the redox state of an electron carrier connecting photosystems I and II. CSK therefore provides a redox regulatory mechanism that couples photosynthesis to gene expression. This mechanism is inherited directly from the cyanobacterial ancestor of chloroplasts, is intrinsic to chloroplasts, and is targeted to chloroplast genes.
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Affiliation(s)
- Sujith Puthiyaveetil
- *School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom
| | | | - Peter Cain
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - James A. Sullivan
- *School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom
| | - Christine A. Newell
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, United Kingdom; and
| | - John C. Gray
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, United Kingdom; and
| | - Colin Robinson
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Mark van der Giezen
- Centre for Eukaryotic Evolutionary Microbiology, School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom
| | - Matthew B. Rogers
- Centre for Eukaryotic Evolutionary Microbiology, School of Biosciences, University of Exeter, Exeter EX4 4QD, United Kingdom
| | - John F. Allen
- *School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom
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Koussevitzky S, Ne'eman E, Peleg S, Harel E. Polyphenol oxidase can cross thylakoids by both the Tat and the Sec-dependent pathways: a putative role for two stromal processing sites. PHYSIOLOGIA PLANTARUM 2008; 133:266-77. [PMID: 18331405 DOI: 10.1111/j.1399-3054.2008.01074.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Polyphenol oxidase (PPO; EC 1.10.3.2 or EC 1.14.18.1), a thylakoid-lumen protein encoded by a nuclear gene, plays a role in the defense of plants against both herbivores and pathogens. Although previously reported to be a Tat (twin-arginine-dependent translocation) protein, the import of PPO by isolated chloroplasts was inhibited by azide, a diagnostic inhibitor of the Sec-dependent pathway. Import of PPO inhibited thylakoid translocation of a Tat protein and did not affect translocation of Sec-dependent proteins. In contrast, a pre-accumulated iPPO competed with Sec-dependent but not with Tat proteins. A previously reported second processing step in the stroma removes a twin-Arg that is part of a 'Sec-avoidance' motif in the thylakoid targeting domain of PPO. When the second processing site was mutated, the import of the resulting precursor showed Sec-dependent characteristics. The PPO transit peptide could drive thylakoid translocation of a Tat protein in the dark. Azide inhibited the secretion of a PPO intermediate that lacks a twin-Arg to the periplasm of Escherichia coli, but had no effect on the export of the intermediate containing the twin-Arg. PPO is synthesized in plants in response to wound and pathogen-related signals and it is possible that when the Tat pathway is unable to translocate adequate amounts of newly synthesized PPO, translocation is diverted to the Sec-dependent pathway by processing the intermediate at the second site and removing the twin-Arg.
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Affiliation(s)
- Shai Koussevitzky
- Department of Plant Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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20
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The twin-arginine transport system: moving folded proteins across membranes. Biochem Soc Trans 2008; 35:835-47. [PMID: 17956229 DOI: 10.1042/bst0350835] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The Tat (twin-arginine transport) pathway is a protein-targeting system dedicated to the transmembrane translocation of fully folded proteins. This system is highly prevalent in the cytoplasmic membranes of bacteria and archaea, and is also found in the thylakoid membranes of plant chloroplasts and possibly also in the inner membrane of plant mitochondria. Proteins are targeted to a membrane-embedded Tat translocase by specialized N-terminal twin-arginine signal peptides bearing an SRRXFLK amino acid motif. The genes encoding components of the Tat translocase were discovered approx. 10 years ago, and, since then, research in this area has expanded on a global scale. In this review, the key discoveries in this field are summarized, and recent studies of bacterial twin-arginine signal-peptide-binding proteins are discussed.
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Bally J, Paget E, Droux M, Job C, Job D, Dubald M. Both the stroma and thylakoid lumen of tobacco chloroplasts are competent for the formation of disulphide bonds in recombinant proteins. PLANT BIOTECHNOLOGY JOURNAL 2008; 6:46-61. [PMID: 17944820 DOI: 10.1111/j.1467-7652.2007.00298.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Plant chloroplasts are promising vehicles for recombinant protein production, but the process of protein folding in these organelles is not well understood in comparison with that in prokaryotic systems, such as Escherichia coli. This is particularly true for disulphide bond formation which is crucial for the biological activity of many therapeutic proteins. We have investigated the capacity of tobacco (Nicotiana tabacum) chloroplasts to efficiently form disulphide bonds in proteins by expressing in this plant cell organelle a well-known bacterial enzyme, alkaline phosphatase, whose activity and stability strictly depend on the correct formation of two intramolecular disulphide bonds. Plastid transformants have been generated that express either the mature enzyme, localized in the stroma, or the full-length coding region, including its signal peptide. The latter has the potential to direct the recombinant alkaline phosphatase into the lumen of thylakoids, giving access to this even less well-characterized organellar compartment. We show that the chloroplast stroma supports the formation of an active enzyme, unlike a normal bacterial cytosol. Sorting of alkaline phosphatase to the thylakoid lumen occurs in the plastid transformants translating the full-length coding region, and leads to larger amounts and more active enzyme. These results are compared with those obtained in bacteria. The implications of these findings on protein folding properties and competency of chloroplasts for disulphide bond formation are discussed.
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Affiliation(s)
- Julia Bally
- Bayer BioScience, F-69263 Lyon cedex 09, France
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Brüser T. The twin-arginine translocation system and its capability for protein secretion in biotechnological protein production. Appl Microbiol Biotechnol 2007; 76:35-45. [PMID: 17476499 DOI: 10.1007/s00253-007-0991-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Revised: 04/05/2007] [Accepted: 04/10/2007] [Indexed: 11/28/2022]
Abstract
The biotechnological production of recombinant proteins is challenged by processes that decrease the yield, such as protease action, aggregation, or misfolding. Today, the variation of strains and vector systems or the modulation of inducible promoter activities is commonly used to optimize expression systems. Alternatively, aggregation to inclusion bodies may be a desired starting point for protein isolation and refolding. The discovery of the twin-arginine translocation (Tat) system for folded proteins now opens new perspectives because in most cases, the Tat machinery does not allow the passage of unfolded proteins. This feature of the Tat system can be exploited for biotechnological purposes, as expression systems may be developed that ensure a virtually complete folding of a recombinant protein before purification. This review focuses on the characteristics that make recombinant Tat systems attractive for biotechnology and discusses problems and possible solutions for an efficient translocation of folded proteins.
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Affiliation(s)
- Thomas Brüser
- Institute of Biology, Division of Microbiology, Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Str. 3, 06120, Halle, Germany.
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Abstract
The thylakoid membrane of chloroplasts contains the major photosynthetic complexes, which consist of several either nuclear or chloroplast encoded subunits. The biogenesis of these thylakoid membrane complexes requires coordinated transport and subsequent assembly of the subunits into functional complexes. Nuclear-encoded thylakoid proteins are first imported into the chloroplast and then directed to the thylakoid using different sorting mechanisms. The cpSec pathway and the cpTat pathway are mainly involved in the transport of lumenal proteins, whereas the spontaneous pathway and the cpSRP pathway are used for the insertion of integral membrane proteins into the thylakoid membrane. While cpSec-, cpTat- and cpSRP-mediated targeting can be classified as 'assisted' mechanisms involving numerous components, 'unassisted' spontaneous insertion does not require additional targeting factors. However, even the assisted pathways differ fundamentally with respect to stromal targeting factors, the composition of the translocase and energy requirements.
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Affiliation(s)
- Danja Schünemann
- Lehrstuhl für Allgemeine und Molekulare Botanik, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
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Cline K, Theg SM. The Sec and Tat Protein Translocation Pathways in Chloroplasts. MOLECULAR MACHINES INVOLVED IN PROTEIN TRANSPORT ACROSS CELLULAR MEMBRANES 2007. [DOI: 10.1016/s1874-6047(07)25018-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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Abstract
The twin-arginine translocation (Tat) pathway is responsible for the export of folded proteins across the cytoplasmic membrane of bacteria. Substrates for the Tat pathway include redox enzymes requiring cofactor insertion in the cytoplasm, multimeric proteins that have to assemble into a complex prior to export, certain membrane proteins, and proteins whose folding is incompatible with Sec export. These proteins are involved in a diverse range of cellular activities including anaerobic metabolism, cell envelope biogenesis, metal acquisition and detoxification, and virulence. The Escherichia coli translocase consists of the TatA, TatB, and TatC proteins, but little is known about the precise sequence of events that leads to protein translocation, the energetic requirements, or the mechanism that prevents the export of misfolded proteins. Owing to the unique characteristics of the pathway, it holds promise for biotechnological applications.
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Affiliation(s)
- Philip A Lee
- Institute for Cellular and Molecular Biology, Department of Chemical Engineering, University of Texas, Austin, Texas 78712-0231, USA.
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Di Cola A, Bailey S, Robinson C. The thylakoid delta pH/delta psi are not required for the initial stages of Tat-dependent protein transport in tobacco protoplasts. J Biol Chem 2005; 280:41165-70. [PMID: 16215228 DOI: 10.1074/jbc.m509215200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The twin-arginine translocation (Tat) system transports folded proteins across the chloroplast thylakoid membrane and bacterial plasma membrane. In vitro import assays have pointed to a key role for the thylakoid delta pH in the initial assembly of the full translocon from two subcomplexes; more generally, the delta pH is believed to provide the overall driving force for translocation. Here, we have studied the role of the delta pH in vivo by analyzing the translocation of Tat substrates in transfected tobacco protoplasts. We show that the complete maturation of the precursor of the 23-kDa lumenal protein (pre-23K) and of a fusion of the 23K presequence linked to green fluorescent protein (pre-GFP) are unaffected by dissipation of the delta pH. High level expression of Tat substrates in protoplasts has recently been shown to result in "translocation reversal" in that a large proportion of a given substrate is partially translocated across the thylakoid membrane, processed to the mature size, and returned to the stroma. However, the efficiency of translocation of pre-23K is undiminished in the absence of the delta pH and/or delta psi, and the rate and extent of maturation of both pre-23K and pre-GFP by the lumen-facing processing peptidase is similarly unaffected. These data demonstrate that the proton motive force is not required for the functional assembly of the Tat translocon and the initial stages of translocation in higher plant chloroplasts in vivo. We conclude that unknown factors play an influential role in both the mechanism and energetics of this system under in vivo conditions.
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Affiliation(s)
- Alessandra Di Cola
- Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom
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