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J Bacteriol. 1994 February; 176(3): 804–814.
PMCID: PMC205118

Genetic and molecular characterization of the Escherichia coli secD operon and its products.


The secD operon of Escherichia coli is required for the efficient export of proteins. We have characterized this operon, and found that, in addition to secD and secF, it contains the upstream gene yajC, but not the genes queA or tgt, in contrast to previous reports. An analysis of yajC mutations constructed in vitro and recombined onto the chromosome indicates that yajC is neither essential nor a sec gene. The secD operon is not induced in response to either secretion defects or temperature changes. TnphoA fusions have been used to analyze the topology of SecD in the inner membrane; the protein contains six transmembrane stretches and a large periplasmic domain. TnphoA fusions to SecD and SecF have also been recombined onto the chromosome and used to determine the level of these proteins within the cell. Our results indicate that there are fewer than 30 SecD and SecF molecules per cell.

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Selected References

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  • Akimaru J, Matsuyama S, Tokuda H, Mizushima S. Reconstitution of a protein translocation system containing purified SecY, SecE, and SecA from Escherichia coli. Proc Natl Acad Sci U S A. 1991 Aug 1;88(15):6545–6549. [PubMed]
  • Baba T, Jacq A, Brickman E, Beckwith J, Taura T, Ueguchi C, Akiyama Y, Ito K. Characterization of cold-sensitive secY mutants of Escherichia coli. J Bacteriol. 1990 Dec;172(12):7005–7010. [PMC free article] [PubMed]
  • Beckwith JR, Signer ER, Epstein W. Transposition of the Lac region of E. coli. Cold Spring Harb Symp Quant Biol. 1966;31:393–401. [PubMed]
  • Bremer E, Beck E, Hindennach I, Sonntag I, Henning U. Cloned structural gene (ompA) for an integral outer membrane protein of Escherichia coli K-12: localization on hybrid plasmid pTU100 and expression of a fragment of the gene. Mol Gen Genet. 1980;179(1):13–20. [PubMed]
  • Brundage L, Fimmel CJ, Mizushima S, Wickner W. SecY, SecE, and band 1 form the membrane-embedded domain of Escherichia coli preprotein translocase. J Biol Chem. 1992 Feb 25;267(6):4166–4170. [PubMed]
  • Carson MJ, Barondess J, Beckwith J. The FtsQ protein of Escherichia coli: membrane topology, abundance, and cell division phenotypes due to overproduction and insertion mutations. J Bacteriol. 1991 Apr;173(7):2187–2195. [PMC free article] [PubMed]
  • Casadaban MJ. Transposition and fusion of the lac genes to selected promoters in Escherichia coli using bacteriophage lambda and Mu. J Mol Biol. 1976 Jul 5;104(3):541–555. [PubMed]
  • de Bruijn FJ, Lupski JR. The use of transposon Tn5 mutagenesis in the rapid generation of correlated physical and genetic maps of DNA segments cloned into multicopy plasmids--a review. Gene. 1984 Feb;27(2):131–149. [PubMed]
  • Ehrmann M, Boyd D, Beckwith J. Genetic analysis of membrane protein topology by a sandwich gene fusion approach. Proc Natl Acad Sci U S A. 1990 Oct;87(19):7574–7578. [PubMed]
  • Emr SD, Hanley-Way S, Silhavy TJ. Suppressor mutations that restore export of a protein with a defective signal sequence. Cell. 1981 Jan;23(1):79–88. [PubMed]
  • Fandl JP, Cabelli R, Oliver D, Tai PC. SecA suppresses the temperature-sensitive SecY24 defect in protein translocation in Escherichia coli membrane vesicles. Proc Natl Acad Sci U S A. 1988 Dec;85(23):8953–8957. [PubMed]
  • Fikes JD, Bassford PJ., Jr Novel secA alleles improve export of maltose-binding protein synthesized with a defective signal peptide. J Bacteriol. 1989 Jan;171(1):402–409. [PMC free article] [PubMed]
  • Fitts R, Reuveny Z, van Amsterdam J, Mulholland J, Botstein D. Substitution of tyrosine for either cysteine in beta-lactamase prevents release from the membrane during secretion. Proc Natl Acad Sci U S A. 1987 Dec;84(23):8540–8543. [PubMed]
  • Gardel C, Benson S, Hunt J, Michaelis S, Beckwith J. secD, a new gene involved in protein export in Escherichia coli. J Bacteriol. 1987 Mar;169(3):1286–1290. [PMC free article] [PubMed]
  • Gardel C, Johnson K, Jacq A, Beckwith J. The secD locus of E.coli codes for two membrane proteins required for protein export. EMBO J. 1990 Oct;9(10):3209–3216. [PubMed]
  • Geller BL. Electrochemical potential releases a membrane-bound secretion intermediate of maltose-binding protein in Escherichia coli. J Bacteriol. 1990 Sep;172(9):4870–4876. [PMC free article] [PubMed]
  • Geller BL, Green HM. Translocation of pro-OmpA across inner membrane vesicles of Escherichia coli occurs in two consecutive energetically distinct steps. J Biol Chem. 1989 Oct 5;264(28):16465–16469. [PubMed]
  • Guzman LM, Barondess JJ, Beckwith J. FtsL, an essential cytoplasmic membrane protein involved in cell division in Escherichia coli. J Bacteriol. 1992 Dec;174(23):7716–7728. [PMC free article] [PubMed]
  • Kohara Y, Akiyama K, Isono K. The physical map of the whole E. coli chromosome: application of a new strategy for rapid analysis and sorting of a large genomic library. Cell. 1987 Jul 31;50(3):495–508. [PubMed]
  • Kumamoto CA, Beckwith J. Evidence for specificity at an early step in protein export in Escherichia coli. J Bacteriol. 1985 Jul;163(1):267–274. [PMC free article] [PubMed]
  • Kumamoto CA, Gannon PM. Effects of Escherichia coli secB mutations on pre-maltose binding protein conformation and export kinetics. J Biol Chem. 1988 Aug 15;263(23):11554–11558. [PubMed]
  • Laemmli UK. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. [PubMed]
  • Lee CA, Beckwith J. Suppression of growth and protein secretion defects in Escherichia coli secA mutants by decreasing protein synthesis. J Bacteriol. 1986 Jun;166(3):878–883. [PMC free article] [PubMed]
  • Lin-Chao S, Chen WT, Wong TT. High copy number of the pUC plasmid results from a Rom/Rop-suppressible point mutation in RNA II. Mol Microbiol. 1992 Nov;6(22):3385–3393. [PubMed]
  • Lopilato J, Bortner S, Beckwith J. Mutations in a new chromosomal gene of Escherichia coli K-12, pcnB, reduce plasmid copy number of pBR322 and its derivatives. Mol Gen Genet. 1986 Nov;205(2):285–290. [PubMed]
  • Manoil C, Beckwith J. A genetic approach to analyzing membrane protein topology. Science. 1986 Sep 26;233(4771):1403–1408. [PubMed]
  • Matsuyama S, Fujita Y, Mizushima S. SecD is involved in the release of translocated secretory proteins from the cytoplasmic membrane of Escherichia coli. EMBO J. 1993 Jan;12(1):265–270. [PubMed]
  • Matsuyama S, Fujita Y, Sagara K, Mizushima S. Overproduction, purification and characterization of SecD and SecF, integral membrane components of the protein translocation machinery of Escherichia coli. Biochim Biophys Acta. 1992 Jul 13;1122(1):77–84. [PubMed]
  • Michaelis S, Inouye H, Oliver D, Beckwith J. Mutations that alter the signal sequence of alkaline phosphatase in Escherichia coli. J Bacteriol. 1983 Apr;154(1):366–374. [PMC free article] [PubMed]
  • Oliver DB, Beckwith J. E. coli mutant pleiotropically defective in the export of secreted proteins. Cell. 1981 Sep;25(3):765–772. [PubMed]
  • Oliver DB, Beckwith J. Regulation of a membrane component required for protein secretion in Escherichia coli. Cell. 1982 Aug;30(1):311–319. [PubMed]
  • Pogliano KJ, Beckwith J. The Cs sec mutants of Escherichia coli reflect the cold sensitivity of protein export itself. Genetics. 1993 Apr;133(4):763–773. [PubMed]
  • Reuter K, Slany R, Ullrich F, Kersten H. Structure and organization of Escherichia coli genes involved in biosynthesis of the deazaguanine derivative queuine, a nutrient factor for eukaryotes. J Bacteriol. 1991 Apr;173(7):2256–2264. [PMC free article] [PubMed]
  • Riggs PD, Derman AI, Beckwith J. A mutation affecting the regulation of a secA-lacZ fusion defines a new sec gene. Genetics. 1988 Apr;118(4):571–579. [PubMed]
  • Rollo EE, Oliver DB. Regulation of the Escherichia coli secA gene by protein secretion defects: analysis of secA, secB, secD, and secY mutants. J Bacteriol. 1988 Jul;170(7):3281–3282. [PMC free article] [PubMed]
  • Russell CB, Thaler DS, Dahlquist FW. Chromosomal transformation of Escherichia coli recD strains with linearized plasmids. J Bacteriol. 1989 May;171(5):2609–2613. [PMC free article] [PubMed]
  • Sandkvist M, Hirst TR, Bagdasarian M. Minimal deletion of amino acids from the carboxyl terminus of the B subunit of heat-labile enterotoxin causes defects in its assembly and release from the cytoplasmic membrane of Escherichia coli. J Biol Chem. 1990 Sep 5;265(25):15239–15244. [PubMed]
  • Schatz PJ, Bieker KL, Ottemann KM, Silhavy TJ, Beckwith J. One of three transmembrane stretches is sufficient for the functioning of the SecE protein, a membrane component of the E. coli secretion machinery. EMBO J. 1991 Jul;10(7):1749–1757. [PubMed]
  • Slany RK, Kersten H. The promoter of the tgt/sec operon in Escherichia coli is preceded by an upstream activation sequence that contains a high affinity FIS binding site. Nucleic Acids Res. 1992 Aug 25;20(16):4193–4198. [PMC free article] [PubMed]
  • Thomas PS. Hybridization of denatured RNA transferred or dotted nitrocellulose paper. Methods Enzymol. 1983;100:255–266. [PubMed]
  • Ueguchi C, Ito K. Escherichia coli sec mutants accumulate a processed immature form of maltose-binding protein (MBP), a late-phase intermediate in MBP export. J Bacteriol. 1990 Oct;172(10):5643–5649. [PMC free article] [PubMed]
  • von Gabain A, Belasco JG, Schottel JL, Chang AC, Cohen SN. Decay of mRNA in Escherichia coli: investigation of the fate of specific segments of transcripts. Proc Natl Acad Sci U S A. 1983 Feb;80(3):653–657. [PubMed]
  • Wickner W, Driessen AJ, Hartl FU. The enzymology of protein translocation across the Escherichia coli plasma membrane. Annu Rev Biochem. 1991;60:101–124. [PubMed]

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