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. 1983 Nov;156(2):695–702. doi: 10.1128/jb.156.2.695-702.1983

Mechanism of protein excretion by gram-negative bacteria: Pseudomonas aeruginosa exotoxin A.

S Lory, P C Tai, B D Davis
PMCID: PMC217885  PMID: 6415037

Abstract

Excretion of proteins by a cell with a double membrane may involve mechanisms different from secretion across a single membrane. We studied this problem with Pseudomonas aeruginosa exotoxin A. This 68,000-dalton protein was released as rapidly as it was completed; even after short pulse-labeling the cells contained neither the toxin nor a larger precursor. Excretion is evidently cotranslational, since in fractionated lysates the toxin was formed (almost entirely in the mature form) by the membrane-polysome complexes but not by the free polysomes. When the membrane was perturbed by 10% ethanol, the cells stopped excreting the toxin and they accumulated an immunoprecipitable, enzymatically active precursor of 71,000 daltons. The precursor was located entirely in the outer membrane on its outer surface. On removal of the ethanol, the cells again excreted mature toxin, but they did not process or release the previously accumulated precursor. Based on these data, a model for the excretion of exotoxin A is presented.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Bjorn M. J., Iglewski B. H., Ives S. K., Sadoff J. C., Vasil M. L. Effect of iron on yields of exotoxin A in cultures of Pseudomonas aeruginosa PA-103. Infect Immun. 1978 Mar;19(3):785–791. doi: 10.1128/iai.19.3.785-791.1978. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Cheng K. J., Ingram J. M., Costerton J. W. Interactions of alkaline phosphatase and the cell wall of Pseudomonas aeruginosa. J Bacteriol. 1971 Jul;107(1):325–336. doi: 10.1128/jb.107.1.325-336.1971. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Chung D. W., Collier R. J. Enzymatically active peptide from the adenosine diphosphate-ribosylating toxin of Pseudomonas aeruginosa. Infect Immun. 1977 Jun;16(3):832–841. doi: 10.1128/iai.16.3.832-841.1977. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Cleveland D. W., Fischer S. G., Kirschner M. W., Laemmli U. K. Peptide mapping by limited proteolysis in sodium dodecyl sulfate and analysis by gel electrophoresis. J Biol Chem. 1977 Feb 10;252(3):1102–1106. [PubMed] [Google Scholar]
  5. DAVIS B. D., MINGIOLI E. S. Mutants of Escherichia coli requiring methionine or vitamin B12. J Bacteriol. 1950 Jul;60(1):17–28. doi: 10.1128/jb.60.1.17-28.1950. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Davis B. D., Tai P. C. The mechanism of protein secretion across membranes. Nature. 1980 Jan 31;283(5746):433–438. doi: 10.1038/283433a0. [DOI] [PubMed] [Google Scholar]
  7. Hancock R. E., Carey A. M. Outer membrane of Pseudomonas aeruginosa: heat- 2-mercaptoethanol-modifiable proteins. J Bacteriol. 1979 Dec;140(3):902–910. doi: 10.1128/jb.140.3.902-910.1979. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Howard S. P., Buckley J. T. Intracellular accumulation of extracellular proteins by pleiotropic export mutants of Aeromonas hydrophila. J Bacteriol. 1983 Apr;154(1):413–418. doi: 10.1128/jb.154.1.413-418.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Iglewski B. H., Kabat D. NAD-dependent inhibition of protein synthesis by Pseudomonas aeruginosa toxin,. Proc Natl Acad Sci U S A. 1975 Jun;72(6):2284–2288. doi: 10.1073/pnas.72.6.2284. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Jones N. C., Osborn M. J. Translocation of phospholipids between the outer and inner membranes of Salmonella typhimurium. J Biol Chem. 1977 Oct 25;252(20):7405–7412. [PubMed] [Google Scholar]
  11. Langley K. E., Hawrot E., Kennedy E. P. Membrane assembly: movement of phosphatidylserine between the cytoplasmic and outer membranes of Escherichia coli. J Bacteriol. 1982 Dec;152(3):1033–1041. doi: 10.1128/jb.152.3.1033-1041.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Lin J. J., Kanazawa H., Ozols J., Wu H. C. An Escherichia coli mutant with an amino acid alteration within the signal sequence of outer membrane prolipoprotein. Proc Natl Acad Sci U S A. 1978 Oct;75(10):4891–4895. doi: 10.1073/pnas.75.10.4891. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Lory S., Collier R. J. Expression of enzymic activity by exotoxin A from Pseudomonas aeruginosa. Infect Immun. 1980 May;28(2):494–501. doi: 10.1128/iai.28.2.494-501.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Lory S., Tai P. C. Characterization of the phospholipase C gene of Pseudomonas aeruginosa cloned in Escherichia coli. Gene. 1983 Apr;22(1):95–101. doi: 10.1016/0378-1119(83)90068-9. [DOI] [PubMed] [Google Scholar]
  15. Michaelis S., Beckwith J. Mechanism of incorporation of cell envelope proteins in Escherichia coli. Annu Rev Microbiol. 1982;36:435–465. doi: 10.1146/annurev.mi.36.100182.002251. [DOI] [PubMed] [Google Scholar]
  16. Mulford C. A., Osborn M. J. An intermediate step in translocation of lipopolysaccharide to the outer membrane of Salmonella typhimurium. Proc Natl Acad Sci U S A. 1983 Mar;80(5):1159–1163. doi: 10.1073/pnas.80.5.1159. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Osborn M. J., Wu H. C. Proteins of the outer membrane of gram-negative bacteria. Annu Rev Microbiol. 1980;34:369–422. doi: 10.1146/annurev.mi.34.100180.002101. [DOI] [PubMed] [Google Scholar]
  18. Palva E. T., Hirst T. R., Hardy S. J., Holmgren J., Randall L. Synthesis of a precursor to the B subunit of heat-labile enterotoxin in Escherichia coli. J Bacteriol. 1981 Apr;146(1):325–330. doi: 10.1128/jb.146.1.325-330.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Schatz G., Butow R. A. How are proteins imported into mitochondria? Cell. 1983 Feb;32(2):316–318. doi: 10.1016/0092-8674(83)90450-6. [DOI] [PubMed] [Google Scholar]
  20. Smit J., Nikaido H. Outer membrane of gram-negative bacteria. XVIII. Electron microscopic studies on porin insertion sites and growth of cell surface of Salmonella typhimurium. J Bacteriol. 1978 Aug;135(2):687–702. doi: 10.1128/jb.135.2.687-702.1978. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Smith W. P., Tai P. C., Davis B. D. Extracellular labeling of growing secreted polypeptide chains in Bacillus subtilis with diazoiodosulfanilic acid. Biochemistry. 1979 Jan 9;18(1):198–202. doi: 10.1021/bi00568a030. [DOI] [PubMed] [Google Scholar]
  22. Smith W. P., Tai P. C., Thompson R. C., Davis B. D. Extracellular labeling of nascent polypeptides traversing the membrane of Escherichia coli. Proc Natl Acad Sci U S A. 1977 Jul;74(7):2830–2834. doi: 10.1073/pnas.74.7.2830. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Tai P. C., Caulfield M. P., Davis B. D. Synthesis of proteins by membrane-associated polysomes and free polysomes. Methods Enzymol. 1983;97:62–69. doi: 10.1016/0076-6879(83)97119-7. [DOI] [PubMed] [Google Scholar]
  24. Vasil M. L., Kabat D., Iglewski B. H. Structure-activity relationships of an exotoxin of Pseudomonas aeruginosa. Infect Immun. 1977 Apr;16(1):353–361. doi: 10.1128/iai.16.1.353-361.1977. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Wagner W., Vogel M., Goebel W. Transport of hemolysin across the outer membrane of Escherichia coli requires two functions. J Bacteriol. 1983 Apr;154(1):200–210. doi: 10.1128/jb.154.1.200-210.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Wickner W. The assembly of proteins into biological membranes: The membrane trigger hypothesis. Annu Rev Biochem. 1979;48:23–45. doi: 10.1146/annurev.bi.48.070179.000323. [DOI] [PubMed] [Google Scholar]
  27. Zwizinski C., Wickner W. Purification and characterization of leader (signal) peptidase from Escherichia coli. J Biol Chem. 1980 Aug 25;255(16):7973–7977. [PubMed] [Google Scholar]

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