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- Title
Functional analysis of the Salmonella typhimurium invasion genes invl and invJ and identification of a target of the protein secretion apparatus encoded in the inv locus.
- Authors
Collazo, Carmen M.; Zierler, Michael K.; Galán, Jorge E.
- Abstract
We have carried out a functional analysis of <em>invl</em> and <em>invJ</em>, two <em>Salmonella typhimurium</em> genes required for this organism to gain access So cultured mammalian cells. These genes are located immediately downstream of <em>invC</em>, a previously identified gene also required for bacterial invasion. Non-polar mutations in either of these genes rendered <em>S. typhimurium</em> severely defective for entry into cultured epithelial cells, although these mutations did not affect the ability of these organisms to attach to those cells. Nucleotide sequence analysis revealed that the <em>invl</em> and <em>invJ</em> genes encode proteins with molecular weights of 18077 and 36415, respectively. Polypeptides of similar sizes were observed when these genes were expressed in a bacteriophage T7 RNA polymerasebased expression system. Comparison of the predicted sequences of Invl and InvJ with translated sequences in the existing databases indicated that these proteins are Identical to the previously identified <em>S. typhimurium</em> SpaM and SpaN proteins. Further analysis of these sequences revealed regions of homology between Invl and the <em>N</em>-terminus of IpaB of <em>Shigella</em> spp. and between InvJ and EaeB of enteropathogenic <em>Escherichia coli</em>. Localization studies by immunoblot analysis indicated that InvJ is secreted to the culture supernatant, a surprising finding since this protein also lacks a typical signal sequence. Mutations in <em>invG</em> and <em>invC</em>, two members of the <em>Salmonella inv</em> locus, effectively prevented the transport of InvJ to the culture supernatant. Thus, InvJ is the first identified target of the protein secretion apparatus encoded in the <em>inv</em> locus and therefore a candidate to have effector functions related to bacterial entry.
- Subjects
FUNCTIONAL analysis; SALMONELLA typhimurium; SALMONELLA; GENES; CELLS; BACTERIA; NUCLEOTIDE sequence
- Publication
Molecular Microbiology, 1995, Vol 15, Issue 1, p25
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/j.1365-2958.1995.tb02218.x