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Safari M, Yakhchali B, Shariati J V. Comprehensive genomic analysis of an indigenous Pseudomonas pseudoalcaligenes degrading phenolic compounds. Sci Rep 2019; 9:12736. [PMID: 31484962 PMCID: PMC6726644 DOI: 10.1038/s41598-019-49048-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Accepted: 08/15/2019] [Indexed: 11/09/2022] Open
Abstract
Environmental contamination with aromatic compounds is a universal challenge. Aromatic-degrading microorganisms isolated from the same or similar polluted environments seem to be more suitable for bioremediation. Moreover, microorganisms adapted to contaminated environments are able to use toxic compounds as the sole sources of carbon and energy. An indigenous strain of Pseudomonas, isolated from the Mahshahr Petrochemical plant in the Khuzestan province, southwest of Iran, was studied genetically. It was characterized as a novel Gram-negative, aerobic, halotolerant, rod-shaped bacterium designated Pseudomonas YKJ, which was resistant to chloramphenicol and ampicillin. Genome of the strain was completely sequenced using Illumina technology to identify its genetic characteristics. MLST analysis revealed that the YKJ strain belongs to the genus Pseudomonas indicating the highest sequence similarity with Pseudomonas pseudoalcaligenes strain CECT 5344 (99% identity). Core- and pan-genome analysis indicated that P. pseudoalcaligenes contains 1,671 core and 3,935 unique genes for coding DNA sequences. The metabolic and degradation pathways for aromatic pollutants were investigated using the NCBI and KEGG databases. Genomic and experimental analyses showed that the YKJ strain is able to degrade certain aromatic compounds including bisphenol A, phenol, benzoate, styrene, xylene, benzene and chlorobenzene. Moreover, antibiotic resistance and chemotaxis properties of the YKJ strain were found to be controlled by two-component regulatory systems.
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Affiliation(s)
- Maryam Safari
- Department of Energy and Environmental Biotechnology, Institute of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, I. R., Iran.,Department of Biology, Faculty of Science, Nour Danesh Institute of Higher Education, Isfahan Province, Meymeh, Danesh Blvd, I. R, Iran
| | - Bagher Yakhchali
- Department of Energy and Environmental Biotechnology, Institute of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, I. R., Iran.
| | - Vahid Shariati J
- Department of Plant Molecular Biotechnology, Institute of Agricultural Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Tehran, I. R., Iran
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2
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Lu J, Zhang J. Extracellular expression of Aerococcus viridans pyruvate oxidase in recombinant Escherichia coli through SecB co-expression. RSC Adv 2019; 9:26291-26301. [PMID: 35531014 PMCID: PMC9070445 DOI: 10.1039/c9ra04765d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 08/15/2019] [Indexed: 11/21/2022] Open
Abstract
Pyruvate oxidase (POD) is an important enzyme used for clinical applications and biochemical analyses, and recombinant Escherichia coli strains expressing Aerococcus viridans POD have been frequently employed for obtaining high POD yield. Although significant progress has been achieved in increasing recombinant POD production, intracellular POD expression and weak stability of POD make POD purification difficult. In this study, extracellular POD expression was achieved by co-expression of chaperone SecB under three promoters (T7, lac, bla). The weakest promoter, bla, when compared with T7 and lac promoters, provided the optimum extracellular POD activity among these three promoters. After optimization of cultivation conditions, such as IPTG concentration, pH, and temperature, the extracellular POD yield increased to 795.7 U L-1. Furthermore, by using glycine to disrupt recombinant E. coli cell wall and Cu2+ ions as POD stabilizer, the final extracellular POD yield reached 2926.3 U L-1. The expression intensity of chaperone had significant influence on heterologous protein secretion, and the high yield of extracellular POD implies potential widespread POD production and application.
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Affiliation(s)
- Junwen Lu
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology 516 Jungong Road Shanghai 200093 China +86-21-55271117 +86-21-55803272
| | - Jianguo Zhang
- School of Medical Instrument and Food Engineering, University of Shanghai for Science and Technology 516 Jungong Road Shanghai 200093 China +86-21-55271117 +86-21-55803272
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3
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Jin J, Hsieh YH, Chaudhary AS, Cui J, Houghton JE, Sui SF, Wang B, Tai PC. SecA inhibitors as potential antimicrobial agents: differential actions on SecA-only and SecA-SecYEG protein-conducting channels. FEMS Microbiol Lett 2018; 365:5037921. [PMID: 30007321 PMCID: PMC7190897 DOI: 10.1093/femsle/fny145] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 06/13/2018] [Indexed: 12/13/2022] Open
Abstract
Sec-dependent protein translocation is an essential process in bacteria. SecA is a key component of the translocation machinery and has multiple domains that interact with various ligands. SecA acts as an ATPase motor to drive the precursor protein/peptide through the SecYEG protein translocation channels. As SecA is unique to bacteria and there is no mammalian counterpart, it is an ideal target for the development of new antimicrobials. Several reviews detail the assays for ATPase and protein translocation, as well as the search for SecA inhibitors. Recent studies have shown that, in addition to the SecA-SecYEG translocation channels, there are SecA-only channels in the lipid bilayers, which function independently from the SecYEG machinery. This mini-review focuses on recent advances on the newly developed SecA inhibitors that allow the evaluation of their potential as antimicrobial agents, as well as a fundamental understanding of mechanisms of SecA function(s). These SecA inhibitors abrogate the effects of efflux pumps in both Gram-positive and Gram-negative bacteria. We also discuss recent findings that SecA binds to ribosomes and nascent peptides, which suggest other roles of SecA. A model for the multiple roles of SecA is presented.
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Affiliation(s)
- Jinshan Jin
- Department of Biology, Center for Biotechnology and Drug Design and Georgia State University, Atlanta, GA 30303, USA
| | - Ying-Hsin Hsieh
- Department of Biology, Center for Biotechnology and Drug Design and Georgia State University, Atlanta, GA 30303, USA
| | - Arpana S Chaudhary
- Department of Chemistry, Center for Biotechnology and Drug Design and Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA
| | - Jianmei Cui
- Department of Chemistry, Center for Biotechnology and Drug Design and Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA
| | - John E Houghton
- Department of Biology, Center for Biotechnology and Drug Design and Georgia State University, Atlanta, GA 30303, USA
| | - Sen-fang Sui
- State Key Laboratory of Membrane Biology, Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Binghe Wang
- Department of Chemistry, Center for Biotechnology and Drug Design and Georgia State University, P.O. Box 3965, Atlanta, GA 30303, USA
| | - Phang C Tai
- Department of Biology, Center for Biotechnology and Drug Design and Georgia State University, Atlanta, GA 30303, USA
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Crane JM, Randall LL. The Sec System: Protein Export in Escherichia coli. EcoSal Plus 2017; 7:10.1128/ecosalplus.ESP-0002-2017. [PMID: 29165233 PMCID: PMC5807066 DOI: 10.1128/ecosalplus.esp-0002-2017] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Indexed: 11/20/2022]
Abstract
In Escherichia coli, proteins found in the periplasm or the outer membrane are exported from the cytoplasm by the general secretory, Sec, system before they acquire stably folded structure. This dynamic process involves intricate interactions among cytoplasmic and membrane proteins, both peripheral and integral, as well as lipids. In vivo, both ATP hydrolysis and proton motive force are required. Here, we review the Sec system from the inception of the field through early 2016, including biochemical, genetic, and structural data.
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Affiliation(s)
- Jennine M. Crane
- Department of Biochemistry, University of Missouri, Columbia, Missouri
| | - Linda L. Randall
- Department of Biochemistry, University of Missouri, Columbia, Missouri
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Findik BT, Randall LL. Determination of the intracellular concentration of the export chaperone SecB in Escherichia coli. PLoS One 2017; 12:e0183231. [PMID: 28850586 PMCID: PMC5574556 DOI: 10.1371/journal.pone.0183231] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 08/01/2017] [Indexed: 11/18/2022] Open
Abstract
SecB, a small tetrameric chaperone in Escherichia coli, plays a crucial role during protein export via the general secretory pathway by binding precursor polypeptides in a nonnative conformation and passing them to SecA, the ATPase of the translocon. The dissociation constants for the interactions are known; however to relate studies in vitro to export in a living cell requires knowledge of the concentrations of the proteins in the cell. Presently in the literature there is no report of a rigorous determination of the intracellular concentration of SecB. The values available vary over 60 fold and the details of the techniques used are not given. Here we use quantitative immunoblotting to determine the level of SecB expressed from the chromosome in E.coli grown in two commonly used media. In rich medium SecB was present at 1.6 ± 0.2 μM and in minimal medium at 2.5 ± 0.6 μM. These values allow studies of SecB carried out in vitro to be applied to the situation in the cell as SecB interacts with its binding partners to move precursor polypeptides through the export pathway.
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Affiliation(s)
- Bahar T. Findik
- Department of Biochemistry, University of Missouri, Columbia, Missouri, United States of America
| | - Linda L. Randall
- Department of Biochemistry, University of Missouri, Columbia, Missouri, United States of America
- * E-mail:
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Hsieh YH, Zhang H, Jin J, Dai C, Jiang C, Wang B, Tai PC. Biphasic actions of SecA inhibitors on Prl/Sec suppressors: Possible physiological roles of SecA-only channels. Biochem Biophys Res Commun 2017; 482:296-300. [PMID: 27856243 DOI: 10.1016/j.bbrc.2016.11.057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 11/11/2016] [Indexed: 11/30/2022]
Abstract
SecA is an essential component in the bacterial Sec-dependent protein translocation process. We previously showed that in addition to the ubiquitous, high-affinity SecYEG-SecDF·YajC protein translocation channel, there is a low-affinity SecA-only channel that elicits ion channel activity and promotes protein translocation. The SecA-only channels are less efficient, and like Prl suppressors, lack signal peptide specificity; they function in the absence of signal peptides. The presence of SecYEG-SecDF·YajC alters the sensitivity of ATPase inhibitor Rose Bengal. In this study, we found that the suppressor membranes are much more resistant to inhibition by Rose Bengal. Similar results have been found for a SecA-specific inhibitor. Moreover, biphasic responses of inhibition of ion current and protein translocation activities were observed for many PrlA/SecY and PrlG/SecE suppressor membranes, with a low IC50 value similar to that of the SecA-only channels and a very high IC50. However, the suppressor strains are as sensitive to the inhibitor as the parental strain, suggesting that SecA-only channels have some essential physiological function(s) in the cells that are inhibited by the specific SecA inhibitor.
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Affiliation(s)
- Ying-Hsin Hsieh
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Hao Zhang
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Jinshan Jin
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Chaofeng Dai
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Chun Jiang
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA
| | - Binghe Wang
- Department of Chemistry, Georgia State University, Atlanta, GA 30303, USA
| | - Phang C Tai
- Department of Biology, Georgia State University, Atlanta, GA 30303, USA; Center for Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, USA.
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7
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Hsieh YH, Zhang H, Wang H, Yang H, Jiang C, Sui SF, Tai PC. Reconstitution of functionally efficient SecA-dependent protein-conducting channels: transformation of low-affinity SecA-liposome channels to high-affinity SecA-SecYEG-SecDF·YajC channels. Biochem Biophys Res Commun 2013; 431:388-92. [PMID: 23337498 DOI: 10.1016/j.bbrc.2013.01.042] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 01/10/2013] [Indexed: 11/20/2022]
Abstract
Previous work showed that SecA alone can promote protein translocation and ion-channel activity in liposomes, and that SecYEG increases efficiency as well as signal peptide specificity. We now report that SecDF·YajC further increases translocation and ion-channel activity. These activities of reconstituted SecA-SecYEG-SecDF·YajC-liposome are almost the same as those of native membranes, indicating the transformation of reconstituted functional high-affinity protein-conducting channels from the low-affinity SecA-channels.
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Affiliation(s)
- Ying-hsin Hsieh
- Department of Biology and Center of Biotechnology and Drug Design, Georgia State University, Atlanta, GA 30303, USA
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8
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Massa C, Degrassi G, Devescovi G, Venturi V, Lamba D. Isolation, heterologous expression and characterization of an endo-polygalacturonase produced by the phytopathogen Burkholderia cepacia. Protein Expr Purif 2007; 54:300-8. [DOI: 10.1016/j.pep.2007.03.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Revised: 03/28/2007] [Accepted: 03/28/2007] [Indexed: 10/23/2022]
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9
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Shokri A, Larsson G. Characterisation of the Escherichia coli membrane structure and function during fedbatch cultivation. Microb Cell Fact 2004; 3:9. [PMID: 15282031 PMCID: PMC514524 DOI: 10.1186/1475-2859-3-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2004] [Accepted: 07/28/2004] [Indexed: 11/10/2022] Open
Abstract
Background Important parameters during recombinant protein production in Escherichia coli, such as productivity and protein activity, are affected by the growth rate. This includes the translocation of protein over the membrane to gain better folding capacity or reduced proteolysis. To vary the growth rate two techniques are available: fedbatch and continuous cultivation, both controlled by the ingoing feed rate. Results During fedbatch cultivation, E. coli contains phosphatidylethanolamine, phosphatidylglycerol, cardiolipin and saturated fatty acids in amounts which are stable with growth rate. However, the levels of cardiolipin are very high compared to continuous cultivation. The reason for fedbatch triggering of this metabolism is not known but hypothesised to result from an additional need for carbon and energy. The reason could be the dynamic and sometimes rapid changes in growth rate to which the fedbatch cell has at all times to adjust. The membrane flexibility, essential for translocation of various components, is however to some degree sustained by production of increased amounts of unsaturated fatty acids in phosphatidylglycerol. The result is a functionally stiff membrane which generally promotes low cell lysis and is constant with respect to protein leakage to the medium. At comparatively high growth rates, when the further stabilising effect of cyclic fatty acids is gone, the high level of unsaturated fatty acids results in a pronounced effect upon sonication. This is very much in contrast to the membrane function in continuous cultivation which shows very specific characteristics as a function of growth rate. Conclusions The stiff and unchanging fedbatch membrane should promote a stable behaviour during downstream processing and is less dependent on the time of harvest. However, optimisation of protein leakage can only be achieved in the continuously cultivated cell where leakage is twice as high compared to the constant leakage level in fedbatch. If leakage is undesired, continuous cultivation is also preferred since it can be designed to lead to the lowest values detected. Induction at low growth rate (<0.2 h-1) should be avoided with respect to productivity, in any system, since the specific and total protein production shows their lowest values at this point.
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Affiliation(s)
- Atefeh Shokri
- The Swedish Centre for Bioprocess Technology, Albanova University Centre, KTH SE-106 91 Stockholm, SWEDEN
| | - Gen Larsson
- The Swedish Centre for Bioprocess Technology, Albanova University Centre, KTH SE-106 91 Stockholm, SWEDEN
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Wang HW, Chen Y, Yang H, Chen X, Duan MX, Tai PC, Sui SF. Ring-like pore structures of SecA: implication for bacterial protein-conducting channels. Proc Natl Acad Sci U S A 2003; 100:4221-6. [PMID: 12642659 PMCID: PMC153074 DOI: 10.1073/pnas.0737415100] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
SecA, an essential component of the general protein secretion pathway of bacteria, is present in Escherichia coli as soluble and membrane-integral forms. Here we show by electron microscopy that SecA assumes two characteristic forms in the presence of phospholipid monolayers: dumbbell-shaped elongated structures and ring-like pore structures. The ring-like pore structures with diameters of 8 nm and holes of 2 nm are found only in the presence of anionic phospholipids. These ring-like pore structures with larger 3- to 6-nm holes (without staining) were also observed by atomic force microscopic examination. They do not form in solution or in the presence of uncharged phosphatidylcholine. These ring-like phospholipid-induced pore-structures may form the core of bacterial protein-conducting channels through bacterial membranes.
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Affiliation(s)
- Hong-Wei Wang
- Department of Biological Sciences and Biotechnology, State-Key Laboratory of Biomembranes, Tsinghua University, Beijing 100084, China
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Müller JP, Bron S, Venema G, Maarten van Dijl J. Chaperone-like activities of the CsaA protein of Bacillus subtilis. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 1):77-88. [PMID: 10658654 DOI: 10.1099/00221287-146-1-77] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The growth and protein export defects of Escherichia coli secA51(Ts) strains can be suppressed by the CsaA protein of Bacillus subtilis. The present studies indicate that this effect can be attributed to chaperone-like activities of CsaA. First, CsaA stimulated protein export in secB, groES and dnaJ mutant strains of E. coli. Second, CsaA suppressed the growth defects of dnaK, dnaJ and grpE mutants of E. coli. Third, and most importantly, CsaA exhibited chaperone-like properties by stimulating the reactivation of heat-denatured firefly luciferase in groEL, groES, dnaK and grpE mutant strains of E. coli, and by preventing the aggregation of heat-denatured luciferase in vitro. Thus, it seems that CsaA suppresses the growth and secretion defects of E. coli secA(Ts) strains either by improving the translocation competence of exported pre-proteins, thereby making them better substrates for mutant SecA proteins, or by stimulating the translocation activity of mutant SecA proteins.
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Affiliation(s)
- Jörg P Müller
- Institute for Molecular Biology, Jena University, Winzerlaer Strasse 10, 07745 Jena, Germany1
| | - Sierd Bron
- Department of Genetics, Center for Biological Sciences, Kerklaan 30, 9751 NN Haren, The Netherlands2
| | - Gerard Venema
- Department of Genetics, Center for Biological Sciences, Kerklaan 30, 9751 NN Haren, The Netherlands2
| | - Jan Maarten van Dijl
- Department of Pharmaceutical Biology, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands3
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Abstract
Protein translocation through the cytoplasmic membrane of Escherichia coli involves cytosolic chaperones. The export-dedicated chaperone SecB mediates targeting of a subset of pre-proteins. In this report, synthesis of SecB in response to plasmid-mediated overexpression of pre-proteins was studied. Overexpression of SecB-dependent pre-proteins stimulated synthesis of SecB under conditions where the cellular export capacity was saturated or uncomplexed SecB was trapped. On the contrary, overexpression of SecB-independent pre-beta-lactamase reduced the promoter activity of secB. The results suggest that uncomplexed SecB can be sequestered by synthesis of SecB-dependent pre-proteins. Furthermore, these data demonstrate the distinct action of the SecB- and signal recognition particle-dependent protein targeting pathways.
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Affiliation(s)
- J P Müller
- Institute for Molecular Biology, Jena University, Germany.
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13
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Seoh HK, Tai PC. Catabolic repression of secB expression is positively controlled by cyclic AMP (cAMP) receptor protein-cAMP complexes at the transcriptional level. J Bacteriol 1999; 181:1892-9. [PMID: 10074084 PMCID: PMC93590 DOI: 10.1128/jb.181.6.1892-1899.1999] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SecB, a protein export-specific chaperone, enhances the export of a subset of proteins across cytoplasmic membranes of Escherichia coli. Previous studies showed that the synthesis of SecB is repressed by the presence of glucose in the medium. The derepression of SecB requires the products of both the cya and crp genes, indicating that secB expression is under the control of catabolic repression. In this study, two secB-specific promoters were identified. In addition, 5' transcription initiation sites from these two promoters were determined by means of secB-lacZ fusions and primer extension. The distal P1 promoter appeared to be independent of carbon sources, whereas the proximal P2 promoter was shown to be subject to control by the cyclic AMP (cAMP) receptor protein (CRP)-cAMP complexes. Gel-mobility shift studies showed that this regulation results from direct interaction between the secB P2 promoter region and the CRP-cAMP complex. Moreover, the CRP binding site on the secB gene was determined by DNase I footprinting and further substantiated by mutational analysis. The identified secB CRP binding region is centered at the -61.5 region of the secB gene and differed from the putative binding sites predicted by computer analysis.
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Affiliation(s)
- H K Seoh
- Department of Biology, Georgia State University, Atlanta, Georgia 30303, USA
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Abstract
Proteins that perform their activity within the cytoplasmic membrane or outside this cell boundary must be targeted to the translocation site prior to their insertion and/or translocation. In bacteria, several targeting routes are known; the SecB- and the signal recognition particle-dependent pathways are the best characterized. Recently, evidence for the existence of a third major route, the twin-Arg pathway, was gathered. Proteins that use either one of these three different pathways possess special features that enable their specific interaction with the components of the targeting routes. Such targeting information is often contained in an N-terminal extension, the signal sequence, but can also be found within the mature domain of the targeted protein. Once the nascent chain starts to emerge from the ribosome, competition for the protein between different targeting factors begins. After recognition and binding, the targeting factor delivers the protein to the translocation sites at the cytoplasmic membrane. Only by means of a specific interaction between the targeting component and its receptor is the cargo released for further processing and translocation. This mechanism ensures the high-fidelity targeting of premembrane and membrane proteins to the translocation site.
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Affiliation(s)
- P Fekkes
- Department of Microbiology and Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9751 NN Haren, The Netherlands
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