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Hegde RS, Keenan RJ. A unifying model for membrane protein biogenesis. Nat Struct Mol Biol 2024; 31:1009-1017. [PMID: 38811793 PMCID: PMC7616256 DOI: 10.1038/s41594-024-01296-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 03/25/2024] [Indexed: 05/31/2024]
Abstract
α-Helical integral membrane proteins comprise approximately 25% of the proteome in all organisms. The membrane proteome is highly diverse, varying in the number, topology, spacing and properties of transmembrane domains. This diversity imposes different constraints on the insertion of different regions of a membrane protein into the lipid bilayer. Here, we present a cohesive framework to explain membrane protein biogenesis, in which different parts of a nascent substrate are triaged between Oxa1 and SecY family members for insertion. In this model, Oxa1 family proteins insert transmembrane domains flanked by short translocated segments, whereas the SecY channel is required for insertion of transmembrane domains flanked by long translocated segments. Our unifying model rationalizes evolutionary, genetic, biochemical and structural data across organisms and provides a foundation for future mechanistic studies of membrane protein biogenesis.
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Affiliation(s)
- Ramanujan S Hegde
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, UK.
| | - Robert J Keenan
- Gordon Center for Integrative Science, The University of Chicago, Chicago, IL, USA.
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2
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Kaushik S, He H, Dalbey RE. Bacterial Signal Peptides- Navigating the Journey of Proteins. Front Physiol 2022; 13:933153. [PMID: 35957980 PMCID: PMC9360617 DOI: 10.3389/fphys.2022.933153] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 06/21/2022] [Indexed: 11/18/2022] Open
Abstract
In 1971, Blobel proposed the first statement of the Signal Hypothesis which suggested that proteins have amino-terminal sequences that dictate their export and localization in the cell. A cytosolic binding factor was predicted, and later the protein conducting channel was discovered that was proposed in 1975 to align with the large ribosomal tunnel. The 1975 Signal Hypothesis also predicted that proteins targeted to different intracellular membranes would possess distinct signals and integral membrane proteins contained uncleaved signal sequences which initiate translocation of the polypeptide chain. This review summarizes the central role that the signal peptides play as address codes for proteins, their decisive role as targeting factors for delivery to the membrane and their function to activate the translocation machinery for export and membrane protein insertion. After shedding light on the navigation of proteins, the importance of removal of signal peptide and their degradation are addressed. Furthermore, the emerging work on signal peptidases as novel targets for antibiotic development is described.
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3
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Mercier E, Wang X, Bögeholz LAK, Wintermeyer W, Rodnina MV. Cotranslational Biogenesis of Membrane Proteins in Bacteria. Front Mol Biosci 2022; 9:871121. [PMID: 35573737 PMCID: PMC9099147 DOI: 10.3389/fmolb.2022.871121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 04/12/2022] [Indexed: 12/26/2022] Open
Abstract
Nascent polypeptides emerging from the ribosome during translation are rapidly scanned and processed by ribosome-associated protein biogenesis factors (RPBs). RPBs cleave the N-terminal formyl and methionine groups, assist cotranslational protein folding, and sort the proteins according to their cellular destination. Ribosomes translating inner-membrane proteins are recognized and targeted to the translocon with the help of the signal recognition particle, SRP, and SRP receptor, FtsY. The growing nascent peptide is then inserted into the phospholipid bilayer at the translocon, an inner-membrane protein complex consisting of SecY, SecE, and SecG. Folding of membrane proteins requires that transmembrane helices (TMs) attain their correct topology, the soluble domains are inserted at the correct (cytoplasmic or periplasmic) side of the membrane, and – for polytopic membrane proteins – the TMs find their interaction partner TMs in the phospholipid bilayer. This review describes the recent progress in understanding how growing nascent peptides are processed and how inner-membrane proteins are targeted to the translocon and find their correct orientation at the membrane, with the focus on biophysical approaches revealing the dynamics of the process. We describe how spontaneous fluctuations of the translocon allow diffusion of TMs into the phospholipid bilayer and argue that the ribosome orchestrates cotranslational targeting not only by providing the binding platform for the RPBs or the translocon, but also by helping the nascent chains to find their correct orientation in the membrane. Finally, we present the auxiliary role of YidC as a chaperone for inner-membrane proteins. We show how biophysical approaches provide new insights into the dynamics of membrane protein biogenesis and raise new questions as to how translation modulates protein folding.
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4
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Petrů M, Dohnálek V, Füssy Z, Doležal P. Fates of Sec, Tat, and YidC Translocases in Mitochondria and Other Eukaryotic Compartments. Mol Biol Evol 2021; 38:5241-5254. [PMID: 34436602 PMCID: PMC8662606 DOI: 10.1093/molbev/msab253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Formation of mitochondria by the conversion of a bacterial endosymbiont was a key moment in the evolution of eukaryotes. It was made possible by outsourcing the endosymbiont's genetic control to the host nucleus, while developing the import machinery for proteins synthesized on cytosolic ribosomes. The original protein export machines of the nascent organelle remained to be repurposed or were completely abandoned. This review follows the evolutionary fates of three prokaryotic inner membrane translocases Sec, Tat, and YidC. Homologs of all three translocases can still be found in current mitochondria, but with different importance for mitochondrial function. Although the mitochondrial YidC homolog, Oxa1, became an omnipresent independent insertase, the other two remained only sporadically present in mitochondria. Only a single substrate is known for the mitochondrial Tat and no function has yet been assigned for the mitochondrial Sec. Finally, this review compares these ancestral mitochondrial proteins with their paralogs operating in the plastids and the endomembrane system.
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Affiliation(s)
- Markéta Petrů
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Vít Dohnálek
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Zoltán Füssy
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
| | - Pavel Doležal
- Department of Parasitology, Faculty of Science, Charles University, BIOCEV, Vestec, Czech Republic
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5
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Lateral gate dynamics of the bacterial translocon during cotranslational membrane protein insertion. Proc Natl Acad Sci U S A 2021; 118:2100474118. [PMID: 34162707 PMCID: PMC8256087 DOI: 10.1073/pnas.2100474118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Membrane proteins are inserted into the phospholipid bilayer through a lateral gate in the translocon, SecYEG in bacteria, which is expected to be closed in the resting state. Here, we use single-molecule FRET to study the translocon dynamics on timescales ranging from submilliseconds to seconds. We show that the lateral gate is highly dynamic, fluctuating through a continuum of states from open to closed. The insertase YidC facilitates the insertion of transmembrane helices by shifting the fluctuations toward more open conformations. Spontaneous fluctuations allow the gate to rapidly release newly synthesized transmembrane segments into the phospholipid bilayer during ongoing translation. The results highlight the important role of rapid spontaneous fluctuations during the key step in the biogenesis of inner-membrane proteins. During synthesis of membrane proteins, transmembrane segments (TMs) of nascent proteins emerging from the ribosome are inserted into the central pore of the translocon (SecYEG in bacteria) and access the phospholipid bilayer through the open lateral gate formed of two helices of SecY. Here we use single-molecule fluorescence resonance energy transfer to monitor lateral-gate fluctuations in SecYEG embedded in nanodiscs containing native membrane phospholipids. We find the lateral gate to be highly dynamic, sampling the whole range of conformations between open and closed even in the absence of ligands, and we suggest a statistical model-free approach to evaluate the ensemble dynamics. Lateral gate fluctuations take place on both short (submillisecond) and long (subsecond) timescales. Ribosome binding and TM insertion do not halt fluctuations but tend to increase sampling of the open state. When YidC, a constituent of the holotranslocon, is bound to SecYEG, TM insertion facilitates substantial opening of the gate, which may aid in the folding of YidC-dependent polytopic membrane proteins. Mutations in lateral gate residues showing in vivo phenotypes change the range of favored states, underscoring the biological significance of lateral gate fluctuations. The results suggest how rapid fluctuations of the lateral gate contribute to the biogenesis of inner-membrane proteins.
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6
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Liu J, Wu P, Guo Q, Lai X, Ruan B, Wang H, Rehman S, Chen M. Kaolinite weakens the co-stress of ampicillin and tetracycline on Escherichia coli through multiple pathways. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:25228-25240. [PMID: 33453031 DOI: 10.1007/s11356-021-12356-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 01/02/2021] [Indexed: 06/12/2023]
Abstract
Ampicillin and tetracycline are common antibiotics and can threaten humans by inducing antibiotic resistance in bacteria. Microorganisms are usually exposed to a mixed antibiotic system in the environment. However, there are few researches on the specific regulatory mechanisms of clay on microorganisms under the stress of complex antibiotics. In this study, tandem mass tag-based coupled with two-dimensional liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) was employed to recognize and quantify changes in protein expression of Escherichia coli (E. coli) after culture for 15 days, with or without kaolinite in the co-stress of ampicillin and tetracycline. The results indicated that kaolinite could activate metabolic pathways of E. coli such as the energy metabolism, the biosynthesis of other secondary metabolites, and the metabolism of cofactors and vitamins. Particularly, the fatty acid degradation pathway has also been promoted, indicating that in the same unfavorable environment, kaolinite might influence the composition of E. coli cell membranes. This might be due to the change in membrane composition that was a kind of adaptive strategy of bacterial evolution. Moreover, kaolinite could promote multidrug efflux system to export the bacterial intracellular toxic substances, making E. coli survive better in an adverse environment. Consequently, this study not only disclosed the regulation of kaolinite on E. coli in a complex antibiotic environment but also provided new insights into the environmental process of antibiotic resistance.
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Affiliation(s)
- Juan Liu
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, People's Republic of China
| | - Pingxiao Wu
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, People's Republic of China.
- The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, Guangzhou, 510006, People's Republic of China.
- Guangdong Provincial Key Laboratory of Solid Wastes Pollution Control and Recycling, South China University of Technology, Guangzhou, 510006, People's Republic of China.
- Guangdong Provincial Engineering and Technology Research Center for Environmental Risk Prevention and Emergency Disposal, Guangzhou, 510006, People's Republic of China.
- Guangdong Engineering and Technology Research Center for Environmental Nanomaterials, Guangzhou, 510006, People's Republic of China.
| | - Qing Guo
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, People's Republic of China
| | - Xiaolin Lai
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, People's Republic of China
| | - Bo Ruan
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, People's Republic of China
| | - Huimin Wang
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, People's Republic of China
| | - Saeed Rehman
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, People's Republic of China
| | - Meiqing Chen
- School of Environment and Energy, South China University of Technology, Guangzhou, 510006, People's Republic of China
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7
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Tracking the Stepwise Movement of a Membrane-inserting Protein In Vivo. J Mol Biol 2020; 432:484-496. [DOI: 10.1016/j.jmb.2019.10.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 10/10/2019] [Accepted: 10/11/2019] [Indexed: 12/13/2022]
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8
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Abstract
ABSTRACT
YidC insertase plays a pivotal role in the membrane integration, folding, and assembly of a number of proteins, including energy-transducing respiratory complexes, both autonomously and in concert with the SecYEG channel in bacteria. The YidC family of proteins is widely conserved in all domains of life, with new members recently identified in the eukaryotic endoplasmic reticulum membrane. Bacterial and organellar members share the conserved 5-transmembrane core, which forms a unique hydrophilic cavity in the inner leaflet of the bilayer accessible from the cytoplasm and the lipid phase. In this chapter, we discuss the YidC family of proteins, focusing on its mechanism of substrate insertion independently and in association with the Sec translocon.
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9
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Chorev DS, Baker LA, Wu D, Beilsten-Edmands V, Rouse SL, Zeev-Ben-Mordehai T, Jiko C, Samsudin F, Gerle C, Khalid S, Stewart AG, Matthews SJ, Grünewald K, Robinson CV. Protein assemblies ejected directly from native membranes yield complexes for mass spectrometry. Science 2018; 362:829-834. [PMID: 30442809 PMCID: PMC6522346 DOI: 10.1126/science.aau0976] [Citation(s) in RCA: 147] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Accepted: 10/08/2018] [Indexed: 12/25/2022]
Abstract
Membrane proteins reside in lipid bilayers and are typically extracted from this environment for study, which often compromises their integrity. In this work, we ejected intact assemblies from membranes, without chemical disruption, and used mass spectrometry to define their composition. From Escherichia coli outer membranes, we identified a chaperone-porin association and lipid interactions in the β-barrel assembly machinery. We observed efflux pumps bridging inner and outer membranes, and from inner membranes we identified a pentameric pore of TonB, as well as the protein-conducting channel SecYEG in association with F1FO adenosine triphosphate (ATP) synthase. Intact mitochondrial membranes from Bos taurus yielded respiratory complexes and fatty acid-bound dimers of the ADP (adenosine diphosphate)/ATP translocase (ANT-1). These results highlight the importance of native membrane environments for retaining small-molecule binding, subunit interactions, and associated chaperones of the membrane proteome.
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Affiliation(s)
- Dror S Chorev
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Lindsay A Baker
- Division of Structural Biology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Di Wu
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Victoria Beilsten-Edmands
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Sarah L Rouse
- Department of Life Sciences, Imperial College, London, South Kensington Campus, London SW7 2AZ, UK
| | | | - Chimari Jiko
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Kumatori, Japan
| | - Firdaus Samsudin
- School of Chemistry, University of Southampton, University Road, Southampton SO17 1BJ, UK
| | - Christoph Gerle
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan
- Core Research for Evolutional Science and Technology, Japan and Science and Technology Agency, Kawaguchi, Japan
| | - Syma Khalid
- School of Chemistry, University of Southampton, University Road, Southampton SO17 1BJ, UK
| | - Alastair G Stewart
- Molecular, Structural and Computational Biology Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- Faculty of Medicine, The University of New South Wales, Sydney, NSW, Australia
| | - Stephen J Matthews
- Department of Life Sciences, Imperial College, London, South Kensington Campus, London SW7 2AZ, UK
| | - Kay Grünewald
- Division of Structural Biology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
- Centre of Structural Systems Biology (CSSB), Notkestr. 85, D-22607, Heinrich-Pette Institute/University of Hamburg, Hamburg, Germany
| | - Carol V Robinson
- Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK.
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10
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Sachelaru I, Winter L, Knyazev DG, Zimmermann M, Vogt A, Kuttner R, Ollinger N, Siligan C, Pohl P, Koch HG. YidC and SecYEG form a heterotetrameric protein translocation channel. Sci Rep 2017; 7:101. [PMID: 28273911 PMCID: PMC5427846 DOI: 10.1038/s41598-017-00109-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 02/08/2017] [Indexed: 11/26/2022] Open
Abstract
The heterotrimeric SecYEG complex cooperates with YidC to facilitate membrane protein insertion by an unknown mechanism. Here we show that YidC contacts the interior of the SecY channel resulting in a ligand-activated and voltage-dependent complex with distinct ion channel characteristics. The SecYEG pore diameter decreases from 8 Å to only 5 Å for the YidC-SecYEG pore, indicating a reduction in channel cross-section by YidC intercalation. In the presence of a substrate, YidC relocates to the rim of the pore as indicated by increased pore diameter and loss of YidC crosslinks to the channel interior. Changing the surface charge of the pore by incorporating YidC into the channel wall increases the anion selectivity, and the accompanying change in wall hydrophobicity is liable to alter the partition of helices from the pore into the membrane. This could explain how the exit of transmembrane domains from the SecY channel is facilitated by YidC.
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Affiliation(s)
- Ilie Sachelaru
- grid.5963.9Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Stefan Meier Str. 17, Freiburg, 79104 Germany ,grid.5963.9Fakultät für Biologie, Albert-Ludwigs-Universität Freiburg, Stefan Meier Str. 17, 79104 Freiburg, Germany
| | - Lukas Winter
- 0000 0001 1941 5140grid.9970.7Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria
| | - Denis G. Knyazev
- 0000 0001 1941 5140grid.9970.7Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria
| | - Mirjam Zimmermann
- 0000 0001 1941 5140grid.9970.7Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria
| | - Andreas Vogt
- grid.5963.9Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Stefan Meier Str. 17, Freiburg, 79104 Germany ,grid.5963.9Fakultät für Biologie, Albert-Ludwigs-Universität Freiburg, Stefan Meier Str. 17, 79104 Freiburg, Germany ,grid.5963.9Spemann-Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-Universität Freiburg, 79104 Freiburg, Germany
| | - Roland Kuttner
- 0000 0001 1941 5140grid.9970.7Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria
| | - Nicole Ollinger
- 0000 0001 1941 5140grid.9970.7Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria
| | - Christine Siligan
- 0000 0001 1941 5140grid.9970.7Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020 Linz, Austria
| | - Peter Pohl
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40, A-4020, Linz, Austria.
| | - Hans-Georg Koch
- Institut für Biochemie und Molekularbiologie, ZBMZ, Faculty of Medicine, Albert-Ludwigs-Universität Freiburg, Stefan Meier Str. 17, Freiburg, 79104, Germany. .,Spemann-Graduate School of Biology and Medicine (SGBM), Albert-Ludwigs-Universität Freiburg, 79104, Freiburg, Germany.
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11
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Analysis of an N-terminal deletion in subunit a of the Escherichia coli ATP synthase. J Bioenerg Biomembr 2017; 49:171-181. [PMID: 28078625 DOI: 10.1007/s10863-017-9694-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 01/04/2017] [Indexed: 10/20/2022]
Abstract
Subunit a is a membrane-bound stator subunit of the ATP synthase and is essential for proton translocation. The N-terminus of subunit a in E. coli is localized to the periplasm, and contains a sequence motif that is conserved among some bacteria. Previous work has identified mutations in this region that impair enzyme activity. Here, an internal deletion was constructed in subunit a in which residues 6-20 were replaced by a single lysine residue, and this mutant was unable to grow on succinate minimal medium. Membrane vesicles prepared from this mutant lacked ATP synthesis and ATP-driven proton translocation, even though immunoblots showed a significant level of subunit a. Similar results were obtained after purification and reconstitution of the mutant ATP synthase into liposomes. The location of subunit a with respect to its neighboring subunits b and c was probed by introducing cysteine substitutions that were known to promote cross-linking: a_L207C + c_I55C, a_L121C + b_N4C, and a_T107C + b_V18C. The last pair was unable to form cross-links in the background of the deletion mutant. The results indicate that loss of the N-terminal region of subunit a does not generally disrupt its structure, but does alter interactions with subunit b.
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12
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Membrane protein insertion and assembly by the bacterial holo-translocon SecYEG-SecDF-YajC-YidC. Biochem J 2016; 473:3341-54. [PMID: 27435098 PMCID: PMC5095914 DOI: 10.1042/bcj20160545] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 07/19/2016] [Indexed: 02/03/2023]
Abstract
Protein secretion and membrane insertion occur through the ubiquitous Sec machinery. In this system, insertion involves the targeting of translating ribosomes via the signal recognition particle and its cognate receptor to the SecY (bacteria and archaea)/Sec61 (eukaryotes) translocon. A common mechanism then guides nascent transmembrane helices (TMHs) through the Sec complex, mediated by associated membrane insertion factors. In bacteria, the membrane protein 'insertase' YidC ushers TMHs through a lateral gate of SecY to the bilayer. YidC is also thought to incorporate proteins into the membrane independently of SecYEG. Here, we show the bacterial holo-translocon (HTL) - a supercomplex of SecYEG-SecDF-YajC-YidC - is a bona fide resident of the Escherichia coli inner membrane. Moreover, when compared with SecYEG and YidC alone, the HTL is more effective at the insertion and assembly of a wide range of membrane protein substrates, including those hitherto thought to require only YidC.
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13
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Thakur P, Gantasala NP, Choudhary E, Singh N, Abdin MZ, Agarwal N. The preprotein translocase YidC controls respiratory metabolism in Mycobacterium tuberculosis. Sci Rep 2016; 6:24998. [PMID: 27166092 PMCID: PMC4863248 DOI: 10.1038/srep24998] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 04/08/2016] [Indexed: 12/02/2022] Open
Abstract
The YidC–Oxa1–Alb3 preprotein translocases play a vital role in membrane insertion of proteins in eukaryotes and bacteria. In a recent study we observed that Rv3921c, which encodes putative YidC translocase in Mycobacterium tuberculosis (Mtb), is essential for in vitro growth of bacteria. However, the exact function of this particular protein remains to identify in mycobacterial pathogens. By performing a systematic study here we show that YidC of Mtb is an envelope protein, which is required for production of ATP and maintenance of cellular redox balance. Drastic effects of depletion of Rv3921c on the expression of hypoxic genes, ATP synthases, and many proteins of central metabolic and respiratory pathways shed a significant light on the function of YidC towards controlling respiratory metabolism in Mtb. Association of YidC with proteins such as succinate dehydrogenases and ubiquinol-cytochrome C reductase further confirms its role in respiration. Finally we demonstrate that YidC is required for the intracellular survival of Mtb in human macrophages.
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Affiliation(s)
- Preeti Thakur
- Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad 121001 India.,Faculty of Science, Jamia Hamdard, Hamdard Nagar, New Delhi-110062, India
| | - Nagavara Prasad Gantasala
- Regional Center for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad- 121001 India
| | - Eira Choudhary
- Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad 121001 India.,Symbiosis School of Biomedical Sciences, Symbiosis International University, Lavale, Pune- 412115 (Maharashtra) India
| | - Nirpendra Singh
- Regional Center for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad- 121001 India
| | - Malik Zainul Abdin
- Faculty of Science, Jamia Hamdard, Hamdard Nagar, New Delhi-110062, India
| | - Nisheeth Agarwal
- Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad 121001 India
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14
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Abstract
The YidC/Alb3/Oxa1 family functions in the insertion and folding of proteins in the bacterial cytoplasmic membrane, the chloroplast thylakoid membrane, and the mitochondrial inner membrane. All members share a conserved region composed of five transmembrane regions. These proteins mediate membrane insertion of an assorted group of proteins, ranging from respiratory subunits in the mitochondria and light-harvesting chlorophyll-binding proteins in chloroplasts to ATP synthase subunits in bacteria. This review discusses the YidC/Alb3/Oxa1 protein family as well as their function in membrane insertion and two new structures of the bacterial YidC, which suggest a mechanism for membrane insertion by this family of insertases.
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Affiliation(s)
- Seth W Hennon
- From the Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Raunak Soman
- From the Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Lu Zhu
- From the Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
| | - Ross E Dalbey
- From the Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210
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15
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Rühle T, Leister D. Assembly of F1F0-ATP synthases. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:849-60. [PMID: 25667968 DOI: 10.1016/j.bbabio.2015.02.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Revised: 01/28/2015] [Accepted: 02/02/2015] [Indexed: 12/31/2022]
Abstract
F1F0-ATP synthases are multimeric protein complexes and common prerequisites for their correct assembly are (i) provision of subunits in appropriate relative amounts, (ii) coordination of membrane insertion and (iii) avoidance of assembly intermediates that uncouple the proton gradient or wastefully hydrolyse ATP. Accessory factors facilitate these goals and assembly occurs in a modular fashion. Subcomplexes common to bacteria and mitochondria, but in part still elusive in chloroplasts, include a soluble F1 intermediate, a membrane-intrinsic, oligomeric c-ring, and a membrane-embedded subcomplex composed of stator subunits and subunit a. The final assembly step is thought to involve association of the preformed F1-c10-14 with the ab2 module (or the ab8-stator module in mitochondria)--mediated by binding of subunit δ in bacteria or OSCP in mitochondria, respectively. Despite the common evolutionary origin of F1F0-ATP synthases, the set of auxiliary factors required for their assembly in bacteria, mitochondria and chloroplasts shows clear signs of evolutionary divergence. This article is part of a Special Issue entitled: Chloroplast Biogenesis.
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Affiliation(s)
- Thilo Rühle
- Plant Molecular Biology (Botany), Department Biology I, Ludwig-Maximilians-Universität München (LMU), Großhaderner Straße 2, 82152 Planegg-Martinsried, Germany.
| | - Dario Leister
- Plant Molecular Biology (Botany), Department Biology I, Ludwig-Maximilians-Universität München (LMU), Großhaderner Straße 2, 82152 Planegg-Martinsried, Germany.
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16
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Gillespie JJ, Kaur SJ, Rahman MS, Rennoll-Bankert K, Sears KT, Beier-Sexton M, Azad AF. Secretome of obligate intracellular Rickettsia. FEMS Microbiol Rev 2014; 39:47-80. [PMID: 25168200 DOI: 10.1111/1574-6976.12084] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The genus Rickettsia (Alphaproteobacteria, Rickettsiales, Rickettsiaceae) is comprised of obligate intracellular parasites, with virulent species of interest both as causes of emerging infectious diseases and for their potential deployment as bioterrorism agents. Currently, there are no effective commercially available vaccines, with treatment limited primarily to tetracycline antibiotics, although others (e.g. josamycin, ciprofloxacin, chloramphenicol, and azithromycin) are also effective. Much of the recent research geared toward understanding mechanisms underlying rickettsial pathogenicity has centered on characterization of secreted proteins that directly engage eukaryotic cells. Herein, we review all aspects of the Rickettsia secretome, including six secretion systems, 19 characterized secretory proteins, and potential moonlighting proteins identified on surfaces of multiple Rickettsia species. Employing bioinformatics and phylogenomics, we present novel structural and functional insight on each secretion system. Unexpectedly, our investigation revealed that the majority of characterized secretory proteins have not been assigned to their cognate secretion pathways. Furthermore, for most secretion pathways, the requisite signal sequences mediating translocation are poorly understood. As a blueprint for all known routes of protein translocation into host cells, this resource will assist research aimed at uniting characterized secreted proteins with their apposite secretion pathways. Furthermore, our work will help in the identification of novel secreted proteins involved in rickettsial 'life on the inside'.
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Affiliation(s)
- Joseph J Gillespie
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Simran J Kaur
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - M Sayeedur Rahman
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kristen Rennoll-Bankert
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Khandra T Sears
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Magda Beier-Sexton
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Abdu F Azad
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
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17
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Assembly of the Escherichia coli FoF1 ATP synthase involves distinct subcomplex formation. Biochem Soc Trans 2014; 41:1288-93. [PMID: 24059521 DOI: 10.1042/bst20130096] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The ATP synthase (FoF1) of Escherichia coli couples the translocation of protons across the cytoplasmic membrane by Fo to ATP synthesis or hydrolysis in F1. Whereas good knowledge of the nanostructure and the rotary mechanism of the ATP synthase is at hand, the assembly pathway of the 22 polypeptide chains present in a stoichiometry of ab2c10α3β3γδϵ has so far not received sufficient attention. In our studies, mutants that synthesize different sets of FoF1 subunits allowed the characterization of individually formed stable subcomplexes. Furthermore, the development of a time-delayed in vivo assembly system enabled the subsequent synthesis of particular missing subunits to allow the formation of functional ATP synthase complexes. These observations form the basis for a model that describes the assembly pathway of the E. coli ATP synthase from pre-formed subcomplexes, thereby avoiding membrane proton permeability by a concomitant assembly of the open H+-translocating unit within a coupled FoF1 complex.
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18
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Soman R, Yuan J, Kuhn A, Dalbey RE. Polarity and charge of the periplasmic loop determine the YidC and sec translocase requirement for the M13 procoat lep protein. J Biol Chem 2013; 289:1023-32. [PMID: 24275657 DOI: 10.1074/jbc.m113.522250] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
During membrane biogenesis, the M13 procoat protein is inserted into the lipid bilayer in a strictly YidC-dependent manner with both the hydrophobic signal sequence and the membrane anchor sequence promoting translocation of the periplasmic loop via a hairpin mechanism. Here, we find that the translocase requirements can be altered for PClep in a predictable manner by changing the polarity and charge of the peptide region that is translocated across the membrane. When the polarity of the translocated peptide region is lowered and the charged residues in this region are removed, translocation of this loop region occurs largely by a YidC- and Sec-independent mechanism. When the polarity is increased to that of the wild-type procoat protein, the YidC insertase is essential for translocation. Further increasing the polarity, by adding charged residues, switches the insertion pathway to a YidC/Sec mechanism. Conversely, we find that increasing the hydrophobicity of the transmembrane segments of PClep can decrease the translocase requirement for translocation of the peptide chain. This study provides a framework to understand why the YidC and Sec machineries exist in parallel and demonstrates that the YidC insertase has a limited capacity to translocate a peptide chain on its own.
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Affiliation(s)
- Raunak Soman
- From the Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210 and
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19
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Kedrov A, Sustarsic M, de Keyzer J, Caumanns JJ, Wu ZC, Driessen AJ. Elucidating the Native Architecture of the YidC: Ribosome Complex. J Mol Biol 2013; 425:4112-24. [DOI: 10.1016/j.jmb.2013.07.042] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 06/24/2013] [Accepted: 07/09/2013] [Indexed: 10/26/2022]
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20
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Saraogi I, Shan SO. Co-translational protein targeting to the bacterial membrane. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1843:1433-41. [PMID: 24513458 DOI: 10.1016/j.bbamcr.2013.10.013] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Revised: 10/09/2013] [Accepted: 10/16/2013] [Indexed: 12/18/2022]
Abstract
Co-translational protein targeting by the Signal Recognition Particle (SRP) is an essential cellular pathway that couples the synthesis of nascent proteins to their proper cellular localization. The bacterial SRP, which contains the minimal ribonucleoprotein core of this universally conserved targeting machine, has served as a paradigm for understanding the molecular basis of protein localization in all cells. In this review, we highlight recent biochemical and structural insights into the molecular mechanisms by which fundamental challenges faced by protein targeting machineries are met in the SRP pathway. Collectively, these studies elucidate how an essential SRP RNA and two regulatory GTPases in the SRP and SRP receptor (SR) enable this targeting machinery to recognize, sense and respond to its biological effectors, i.e. the cargo protein, the target membrane and the translocation machinery, thus driving efficient and faithful co-translational protein targeting. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Ishu Saraogi
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
| | - Shu-ou Shan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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21
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Role of the twin arginine protein transport pathway in the assembly of the Streptomyces coelicolor cytochrome bc1 complex. J Bacteriol 2013; 196:50-9. [PMID: 24142258 DOI: 10.1128/jb.00776-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The cytochrome bc1-cytochrome aa3 complexes together comprise one of the major branches of the bacterial aerobic respiratory chain. In actinobacteria, the cytochrome bc1 complex shows a number of unusual features in comparison to other cytochrome bc1 complexes. In particular, the Rieske iron-sulfur protein component of this complex, QcrA, is a polytopic rather than a monotopic membrane protein. Bacterial Rieske proteins are usually integrated into the membrane in a folded conformation by the twin arginine protein transport (Tat) pathway. In this study, we show that the activity of the Streptomyces coelicolor M145 cytochrome bc1 complex is dependent upon an active Tat pathway. However, the polytopic Rieske protein is still integrated into the membrane in a ΔtatC mutant strain, indicating that a second protein translocation machinery also participates in its assembly. Difference spectroscopy indicated that the cytochrome c component of the complex was correctly assembled in the absence of the Tat machinery. We show that the intact cytochrome bc1 complex can be isolated from S. coelicolor M145 membranes by affinity chromatography. Surprisingly, a stable cytochrome bc1 complex containing the Rieske protein can be isolated from membranes even when the Tat system is inactive. These findings strongly suggest that the additional transmembrane segments of the S. coelicolor Rieske protein mediate hydrophobic interactions with one or both of the cytochrome subunits.
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22
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Hilbers F, Eggers R, Pradela K, Friedrich K, Herkenhoff-Hesselmann B, Becker E, Deckers-Hebestreit G. Subunit δ is the key player for assembly of the H(+)-translocating unit of Escherichia coli F(O)F1 ATP synthase. J Biol Chem 2013; 288:25880-25894. [PMID: 23864656 DOI: 10.1074/jbc.m113.484675] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ATP synthase (F(O)F1) of Escherichia coli couples the translocation of protons across the cytoplasmic membrane to the synthesis or hydrolysis of ATP. This nanomotor is composed of the rotor c10γε and the stator ab2α3β3δ. To study the assembly of this multimeric enzyme complex consisting of membrane-integral as well as peripheral hydrophilic subunits, we combined nearest neighbor analyses by intermolecular disulfide bond formation or purification of partially assembled F(O)F1 complexes by affinity chromatography with the use of mutants synthesizing different sets of F(O)F1 subunits. Together with a time-delayed in vivo assembly system, the results demonstrate that F(O)F1 is assembled in a modular way via subcomplexes, thereby preventing the formation of a functional H(+)-translocating unit as intermediate product. Surprisingly, during the biogenesis of F(O)F1, F1 subunit δ is the key player in generating stable F(O). Subunit δ serves as clamp between ab2 and c10α3β3γε and guarantees that the open H(+) channel is concomitantly assembled within coupled F(O)F1 to maintain the low membrane proton permeability essential for viability, a general prerequisite for the assembly of multimeric H(+)-translocating enzymes.
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Affiliation(s)
- Florian Hilbers
- From the Department of Microbiology, University of Osnabrück, Barbarastrasse 11, D-49069 Osnabrück, Germany
| | - Ruth Eggers
- From the Department of Microbiology, University of Osnabrück, Barbarastrasse 11, D-49069 Osnabrück, Germany
| | - Kamila Pradela
- From the Department of Microbiology, University of Osnabrück, Barbarastrasse 11, D-49069 Osnabrück, Germany
| | - Kathleen Friedrich
- From the Department of Microbiology, University of Osnabrück, Barbarastrasse 11, D-49069 Osnabrück, Germany
| | | | - Elisabeth Becker
- From the Department of Microbiology, University of Osnabrück, Barbarastrasse 11, D-49069 Osnabrück, Germany
| | - Gabriele Deckers-Hebestreit
- From the Department of Microbiology, University of Osnabrück, Barbarastrasse 11, D-49069 Osnabrück, Germany.
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23
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Time-delayed in vivo assembly of subunit a into preformed Escherichia coli FoF1 ATP synthase. J Bacteriol 2013; 195:4074-84. [PMID: 23836871 DOI: 10.1128/jb.00468-13] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Escherichia coli F(O)F(1) ATP synthase, a rotary nanomachine, is composed of eight different subunits in a α3β3γδεab2c10 stoichiometry. Whereas F(O)F(1) has been studied in detail with regard to its structure and function, much less is known about how this multisubunit enzyme complex is assembled. Single-subunit atp deletion mutants are known to be arrested in assembly, thus leading to formation of partially assembled subcomplexes. To determine whether those subcomplexes are preserved in a stable standby mode, a time-delayed in vivo assembly system was developed. To establish this approach, we targeted the time-delayed assembly of membrane-integrated subunit a into preformed F(O)F(1) lacking subunit a (F(O)F(1)-a) which is known to form stable subcomplexes in vitro. Two expression systems (araBADp and T7p-laco) were adjusted to provide compatible, mutually independent, and sufficiently stringent induction and repression regimens. In detail, all structural atp genes except atpB (encoding subunit a) were expressed under the control of araBADp and induced by arabinose. Following synthesis of F(O)F(1)-a during growth, expression was repressed by glucose/d-fucose, and degradation of atp mRNA controlled by real-time reverse transcription-PCR. A time-delayed expression of atpB under T7p-laco control was subsequently induced in trans by addition of isopropyl-β-d-thiogalactopyranoside. Formation of fully assembled, and functional, F(O)F(1) complexes was verified. This demonstrates that all subunits of F(O)F(1)-a remain in a stable preformed state capable to integrate subunit a as the last subunit. The results reveal that the approach presented here can be applied as a general method to study the assembly of heteromultimeric protein complexes in vivo.
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24
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Zhu L, Wasey A, White SH, Dalbey RE. Charge composition features of model single-span membrane proteins that determine selection of YidC and SecYEG translocase pathways in Escherichia coli. J Biol Chem 2013; 288:7704-7716. [PMID: 23355473 DOI: 10.1074/jbc.m112.429431] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have investigated the features of single-span model membrane proteins based upon leader peptidase that determines whether the proteins insert by a YidC/Sec-independent, YidC-only, or YidC/Sec mechanism. We find that a protein with a highly hydrophobic transmembrane segment that inserts into the membrane by a YidC/Sec-independent mechanism becomes YidC-dependent if negatively charged residues are inserted into the translocated periplasmic domain or if the hydrophobicity of the transmembrane segment is reduced by substituting polar residues for nonpolar ones. This suggests that charged residues in the translocated domain and the hydrophobicity within the transmembrane segment are important determinants of the insertion pathway. Strikingly, the addition of a positively charged residue to either the translocated region or the transmembrane region can switch the insertion requirements such that insertion requires both YidC and SecYEG. To test conclusions from the model protein studies, we confirmed that a positively charged residue is a SecYEG determinant for the endogenous proteins ATP synthase subunits a and b and the TatC subunit of the Tat translocase. These findings provide deeper insights into how pathways are selected for the insertion of proteins into the Escherichia coli inner membrane.
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Affiliation(s)
- Lu Zhu
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210
| | - Abdul Wasey
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210
| | - Stephen H White
- Department of Physiology and Biophysics, University of California, Irvine, California 92697-4560
| | - Ross E Dalbey
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, Ohio 43210.
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25
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Roles of AtpI and two YidC-type proteins from alkaliphilic Bacillus pseudofirmus OF4 in ATP synthase assembly and nonfermentative growth. J Bacteriol 2012; 195:220-30. [PMID: 23123906 DOI: 10.1128/jb.01493-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AtpI, a membrane protein encoded by many bacterial atp operons, is reported to be necessary for c-ring oligomer formation during assembly of some ATP synthase complexes. We investigated chaperone functions of AtpI and compared them to those of AtpZ, a protein encoded by a gene upstream of atpI that has a role in magnesium acquisition at near-neutral pH, and of SpoIIIJ and YqjG, two YidC/OxaI/Alb3 family proteins, in alkaliphilic Bacillus pseudofirmus OF4. A strain with a chromosomal deletion of atpI grew nonfermentatively, and its purified ATP synthase had a c-ring of normal size, indicating that AtpI is not absolutely required for ATP synthase function. However, deletion of atpI, but not atpZ, led to reduced stability of the ATP synthase rotor, reduced membrane association of the F(1) domain, reduced ATPase activity, and modestly reduced nonfermentative growth on malate at both pH 7.5 and 10.5. Both spoIIIJ and yqjG, but not atpI or atpZ, complemented a YidC-depleted Escherichia coli strain. Consistent with such overlapping functions, single deletions of spoIIIJ or yqjG in the alkaliphile did not affect membrane ATP synthase levels or activities, but functional specialization was indicated by YqjG and SpoIIIJ showing respectively greater roles in malate growth at pH 7.5 and 10.5. Expression of yqjG was elevated at pH 7.5 relative to that at pH 10.5 and in ΔspoIIIJ strains, but it was lower than constitutive spoIIIJ expression. Deletion of atpZ caused the largest increase among the mutants in magnesium concentrations needed for pH 7.5 growth. The basis for this phenotype is not yet resolved.
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26
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Uhlemann EME, Pierson HE, Fillingame RH, Dmitriev OY. Cell-free synthesis of membrane subunits of ATP synthase in phospholipid bicelles: NMR shows subunit a fold similar to the protein in the cell membrane. Protein Sci 2012; 21:279-88. [PMID: 22162071 DOI: 10.1002/pro.2014] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 10/20/2011] [Accepted: 11/27/2011] [Indexed: 11/09/2022]
Abstract
NMR structure determination of large membrane proteins is hampered by broad spectral lines, overlap, and ambiguity of signal assignment. Chemical shift and NOE assignment can be facilitated by amino acid selective isotope labeling in cell-free protein synthesis system. However, many biological detergents are incompatible with the cell-free synthesis, and membrane proteins often have to be synthesized in an insoluble form. We report cell-free synthesis of subunits a and c of the proton channel of Escherichia coli ATP synthase in a soluble form in a mixture of phosphatidylcholine derivatives. In comparison, subunit a was purified from the cell-free system and from the bacterial cell membranes. NMR spectra of both preparations were similar, indicating that our procedure for cell-free synthesis produces protein structurally similar to that prepared from the cell membranes.
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Affiliation(s)
- Eva-Maria E Uhlemann
- Department of Biochemistry, University of Saskatchewan, 107 Wiggins Road, Saskatoon, SK, Canada
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27
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Luirink J, Yu Z, Wagner S, de Gier JW. Biogenesis of inner membrane proteins in Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2011; 1817:965-76. [PMID: 22201544 DOI: 10.1016/j.bbabio.2011.12.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Revised: 12/05/2011] [Accepted: 12/12/2011] [Indexed: 11/26/2022]
Abstract
The inner membrane proteome of the model organism Escherichia coli is composed of inner membrane proteins, lipoproteins and peripherally attached soluble proteins. Our knowledge of the biogenesis of inner membrane proteins is rapidly increasing. This is in particular true for the early steps of biogenesis - protein targeting to and insertion into the membrane. However, our knowledge of inner membrane protein folding and quality control is still fragmentary. Furthering our knowledge in these areas will bring us closer to understand the biogenesis of individual inner membrane proteins in the context of the biogenesis of the inner membrane proteome of Escherichia coli as a whole. This article is part of a Special Issue entitled: Biogenesis/Assembly of Respiratory Enzyme Complexes.
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Affiliation(s)
- Joen Luirink
- Section of Molecular Microbiology, Department of Molecular Cell Biology, VU University, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands.
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28
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Pierson HE, Uhlemann EME, Dmitriev OY. Interaction with monomeric subunit c drives insertion of ATP synthase subunit a into the membrane and primes a-c complex formation. J Biol Chem 2011; 286:38583-38591. [PMID: 21900248 DOI: 10.1074/jbc.m111.294868] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Subunit a is the main part of the membrane stator of the ATP synthase molecular turbine. Subunit c is the building block of the membrane rotor. We have generated two molecular fusions of a and c subunits with different orientations of the helical hairpin of subunit c. The a/c fusion protein with correct orientation of transmembrane helices was inserted into the membrane, and co-incorporated into the F(0) complex of ATP synthase with wild type subunit c. The fused c subunit was incorporated into the c-ring tethering the ATP synthase rotor to the stator. The a/c fusion with incorrect orientation of the c-helices required wild type subunit c for insertion into the membrane. In this case, the fused c subunit remained on the periphery of the c-ring and did not interfere with rotor movement. Wild type subunit a inserted into the membrane equally well with wild type subunit c and c-ring assembly mutants that remained monomeric in the membrane. These results show that interaction with monomeric subunit c triggers insertion of subunit a into the membrane, and initiates formation of the a-c complex, the ion-translocating module of the ATP synthase. Correct assembly of the ATP synthase incorporating topologically correct fusion of subunits a and c validates using this model protein for high resolution structural studies of the ATP synthase proton channel.
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Affiliation(s)
- Hannah E Pierson
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Eva-Maria E Uhlemann
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Oleg Y Dmitriev
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada.
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29
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Affiliation(s)
- Ross E. Dalbey
- The Ohio State University, Department of Chemistry, Columbus, Ohio 43210;
| | - Peng Wang
- The Ohio State University, Department of Chemistry, Columbus, Ohio 43210;
| | - Andreas Kuhn
- Institute of Microbiology and Molecular Biology, University of Hohenheim, 70599 Stuttgart, Germany;
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30
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Hartmann C, Engel A. Cloning, expression, purification, and characterization of the membrane protein UncI from Escherichia coli. Protein Expr Purif 2011; 79:187-90. [PMID: 21664273 DOI: 10.1016/j.pep.2011.05.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Revised: 05/24/2011] [Accepted: 05/24/2011] [Indexed: 11/25/2022]
Abstract
The Escherichia coli unc-operon encodes the genes for the subunits of the F0F1-ATP synthase and an integral membrane protein of unknown function called UncI. UncI influences the cell-growth and activity of F0F1, but its exact function is still unknown. The expression level is too low to extract milligram amounts of UncI from E. coli membranes and the existing purification protocol based on methanol/chloroform is not suitable for structural and functional studies. Here we present protocols to increase the expression level, to purify UncI in a detergent where UncI is monodisperse, and we characterize its oligomeric state.
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Affiliation(s)
- Claudia Hartmann
- Center for Cellular Imaging and Nano Analytics, Biozentrum, University of Basel, CH-4058 Basel, Switzerland
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31
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Saller MJ, Otto A, Berrelkamp-Lahpor GA, Becher D, Hecker M, Driessen AJM. Bacillus subtilis YqjG is required for genetic competence development. Proteomics 2010; 11:270-82. [PMID: 21204254 DOI: 10.1002/pmic.201000435] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Revised: 09/21/2010] [Accepted: 10/19/2010] [Indexed: 11/08/2022]
Abstract
Members of the evolutionary conserved Oxa1/Alb3/YidC family have been shown to play an important role in membrane protein insertion, folding and/or assembly. Bacillus subtilis contains two YidC-like proteins, denoted as SpoIIIJ and YqjG. SpoIIIJ and YqjG are largely exchangeable, but SpoIIIJ is essential for spore formation and YqjG cannot complement this activity. To elucidate the role of YqjG, we determined the membrane proteome and functional aspects of B. subtilis cells devoid of SpoIIIJ, YqjG or both. The data show that SpoIIIJ and YqjG have complementary functions in membrane protein insertion and assembly. The reduced levels of F(1)F(O) ATP synthase in cells devoid of both SpoIIIJ and YqjG are due to a defective assembly of the F(1)-domain onto the F(0)-domain. Importantly, for the first time, a specific function is demonstrated for YqjG in genetic competence development.
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Affiliation(s)
- Manfred J Saller
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Haren, The Netherlands
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32
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du Plessis DJF, Nouwen N, Driessen AJM. The Sec translocase. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:851-65. [PMID: 20801097 DOI: 10.1016/j.bbamem.2010.08.016] [Citation(s) in RCA: 195] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Revised: 08/19/2010] [Accepted: 08/20/2010] [Indexed: 11/18/2022]
Abstract
The vast majority of proteins trafficking across or into the bacterial cytoplasmic membrane occur via the translocon. The translocon consists of the SecYEG complex that forms an evolutionarily conserved heterotrimeric protein-conducting membrane channel that functions in conjunction with a variety of ancillary proteins. For posttranslational protein translocation, the translocon interacts with the cytosolic motor protein SecA that drives the ATP-dependent stepwise translocation of unfolded polypeptides across the membrane. For the cotranslational integration of membrane proteins, the translocon interacts with ribosome-nascent chain complexes and membrane insertion is coupled to polypeptide chain elongation at the ribosome. These processes are assisted by the YidC and SecDF(yajC) complex that transiently interacts with the translocon. This review summarizes our current understanding of the structure-function relationship of the translocon and its interactions with ancillary components during protein translocation and membrane protein insertion. This article is part of a Special Issue entitled Protein translocation across or insertion into membranes.
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Affiliation(s)
- David J F du Plessis
- Department of Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute and the Zernike Institute for Advanced Materials, University of Groningen, 9751NN Haren, The Netherlands
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33
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Facey SJ, Kuhn A. Biogenesis of bacterial inner-membrane proteins. Cell Mol Life Sci 2010; 67:2343-62. [PMID: 20204450 PMCID: PMC11115511 DOI: 10.1007/s00018-010-0303-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Revised: 02/01/2010] [Accepted: 02/03/2010] [Indexed: 11/26/2022]
Abstract
All cells must traffic proteins into and across their membranes. In bacteria, several pathways have evolved to enable protein transfer across the inner membrane, the periplasm, and the outer membrane. The major route of protein translocation in and across the cytoplasmic membrane is the general secretion pathway (Sec-pathway). The biogenesis of membrane proteins not only requires protein translocation but also coordinated targeting to the membrane beforehand and folding and assembly into their protein complexes afterwards to function properly in the cell. All these processes are responsible for the biogenesis of membrane proteins that mediate essential functions of the cell such as selective transport, energy conversion, cell division, extracellular signal sensing, and motility. This review will highlight the most recent developments on the structure and function of bacterial membrane proteins, focusing on the journey that integral membrane proteins take to find their final destination in the inner membrane.
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Affiliation(s)
- Sandra J. Facey
- Institute of Microbiology, University of Hohenheim, 70599 Stuttgart, Germany
| | - Andreas Kuhn
- Institute of Microbiology, University of Hohenheim, 70599 Stuttgart, Germany
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F1F0-ATP synthases of alkaliphilic bacteria: lessons from their adaptations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:1362-77. [PMID: 20193659 DOI: 10.1016/j.bbabio.2010.02.028] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Revised: 02/22/2010] [Accepted: 02/23/2010] [Indexed: 12/14/2022]
Abstract
This review focuses on the ATP synthases of alkaliphilic bacteria and, in particular, those that successfully overcome the bioenergetic challenges of achieving robust H+-coupled ATP synthesis at external pH values>10. At such pH values the protonmotive force, which is posited to provide the energetic driving force for ATP synthesis, is too low to account for the ATP synthesis observed. The protonmotive force is lowered at a very high pH by the need to maintain a cytoplasmic pH well below the pH outside, which results in an energetically adverse pH gradient. Several anticipated solutions to this bioenergetic conundrum have been ruled out. Although the transmembrane sodium motive force is high under alkaline conditions, respiratory alkaliphilic bacteria do not use Na+- instead of H+-coupled ATP synthases. Nor do they offset the adverse pH gradient with a compensatory increase in the transmembrane electrical potential component of the protonmotive force. Moreover, studies of ATP synthase rotors indicate that alkaliphiles cannot fully resolve the energetic problem by using an ATP synthase with a large number of c-subunits in the synthase rotor ring. Increased attention now focuses on delocalized gradients near the membrane surface and H+ transfers to ATP synthases via membrane-associated microcircuits between the H+ pumping complexes and synthases. Microcircuits likely depend upon proximity of pumps and synthases, specific membrane properties and specific adaptations of the participating enzyme complexes. ATP synthesis in alkaliphiles depends upon alkaliphile-specific adaptations of the ATP synthase and there is also evidence for alkaliphile-specific adaptations of respiratory chain components.
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Price CE, Driessen AJM. Biogenesis of membrane bound respiratory complexes in Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1803:748-66. [PMID: 20138092 DOI: 10.1016/j.bbamcr.2010.01.019] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 01/21/2010] [Accepted: 01/27/2010] [Indexed: 11/19/2022]
Abstract
Escherichia coli is one of the preferred bacteria for studies on the energetics and regulation of respiration. Respiratory chains consist of primary dehydrogenases and terminal reductases or oxidases linked by quinones. In order to assemble this complex arrangement of protein complexes, synthesis of the subunits occurs in the cytoplasm followed by assembly in the cytoplasm and/or membrane, the incorporation of metal or organic cofactors and the anchoring of the complex to the membrane. In the case of exported metalloproteins, synthesis, assembly and incorporation of metal cofactors must be completed before translocation across the cytoplasmic membrane. Coordination data on these processes is, however, scarce. In this review, we discuss the various processes that respiratory proteins must undergo for correct assembly and functional coupling to the electron transport chain in E. coli. Targeting to and translocation across the membrane together with cofactor synthesis and insertion are discussed in a general manner followed by a review of the coordinated biogenesis of individual respiratory enzyme complexes. Lastly, we address the supramolecular organization of respiratory enzymes into supercomplexes and their localization to specialized domains in the membrane.
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Affiliation(s)
- Claire E Price
- Department of Molecular Microbiology, University of Groningen, 9751 NN Haren, The Netherlands
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Abstract
In all domains of life Oxa1p-like proteins are involved in membrane protein biogenesis. Bacillus subtilis, a model organism for gram-positive bacteria, contains two Oxa1p homologs: SpoIIIJ and YqjG. These molecules appear to be mutually exchangeable, although SpoIIIJ is specifically required for spore formation. SpoIIIJ and YqjG have been implicated in a posttranslocational stage of protein secretion. Here we show that the expression of either spoIIIJ or yqjG functionally compensates for the defects in membrane insertion due to YidC depletion in Escherichia coli. Both SpoIIIJ and YqjG complement the function of YidC in SecYEG-dependent and -independent membrane insertion of subunits of the cytochrome o oxidase and F(1)F(o) ATP synthase complexes. Furthermore, SpoIIIJ and YqjG facilitate membrane insertion of F(1)F(o) ATP synthase subunit c from both E. coli and B. subtilis into inner membrane vesicles of E. coli. When isolated from B. subtilis cells, SpoIIIJ and YqjG were found to be associated with the entire F(1)F(o) ATP synthase complex, suggesting that they have a role late in the membrane assembly process. These data demonstrate that the Bacillus Oxa1p homologs have a role in membrane protein biogenesis rather than in protein secretion.
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