The cryptic general secretory pathway (gsp) operon of Escherichia coli K-12 encodes functional proteins - PubMed (original) (raw)

The cryptic general secretory pathway (gsp) operon of Escherichia coli K-12 encodes functional proteins

O Francetic et al. J Bacteriol. 1996 Jun.

Abstract

Systematic sequencing of the Escherichia coli K-12 chromosome (GenBank entry U18997) has revealed the presence of an apparently complete operon of genes (the gspC-0 operon) similar to genes coding for components of the main terminal branch of the general secretory pathway (e.g., the Klebsiella oxytoca pulC-0 pullulanase secretion operon) and to related genes required for type IV pilus biogenesis. For example, the last gene in the gsp operon, gspO (formerly hopD), encodes a protein which is similar to several type IV prepilin peptidases. Expression of gspO from lacZp promotes cleavage of two known prepilin peptidase substrates in E. coli K-12: Neisseria gonorrhoeae type IV prepilin and K. oxytoca prePulG protein. gspO also complements a mutation in the corresponding gene (pulO) of the pullulanase secretion operon when it is expressed from lacZp. Another gene in the gsp operon, gspG (formerly hopG), encodes a protein similar to prePulG, a component of the pullulanase secretion pathway. Expression of gspG from lacZp leads to production of a protein which (i) is recognized by PulG-specific antiserum (and by antiserum against the Pseudomonas aeruginosa PulG homolog XcpG [formerly XcpT]), (ii) is processed in cells expressing gspO, and (iii) restores secretion in cells carrying a pulG mutation. The chromosomal copies of gspG and gspO are apparently not expressed, probably because of very weak transcription from the upstream region, as measured by using a chromosomal gspC-lacZ operon fusion. Thus, the gsp operon of E. coli K-12 includes at least two functional genes which, together with the rest of the operon, are probably not expressed under laboratory conditions.

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References

    1. Mol Microbiol. 1992 Nov;6(21):3199-211 - PubMed
    1. Mol Microbiol. 1992 May;6(10):1351-61 - PubMed
    1. Mol Microbiol. 1993 Apr;8(2):357-68 - PubMed
    1. J Bacteriol. 1993 Oct;175(20):6695-703 - PubMed
    1. Mol Microbiol. 1993 Jul;9(2):295-308 - PubMed

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