Affiliation:
1. Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
Abstract
ABSTRACT
The
Salmonella enterica
serovar Typhi
ompS2
gene codes for a 362-amino-acid outer membrane protein that contains motifs common to the porin superfamily. It is expressed at very low levels compared to the major OmpC and OmpF porins, as observed for
S. enterica
serovar Typhi OmpS1,
Escherichia coli
OmpN, and
Klebsiella pneumoniae
OmpK37 quiescent porins. A region of 316 bp, between nucleotides −413 and −97 upstream of the transcriptional start point, is involved in negative regulation, as its removal resulted in a 10-fold increase in
ompS2
expression in an
S. enterica
serovar Typhi wild-type strain. This enhancement in expression was not observed in isogenic mutant strains, which had specific deletions of the regulatory
ompB
(
ompR envZ
) operon. Furthermore,
ompS2
expression was substantially reduced in the presence of the OmpR D55A mutant, altered in the major phosphorylation site. Upon random mutagenesis, a mutant where the transposon had inserted into the upstream regulatory region of the gene coding for the LeuO regulator, showed an increased level of
ompS2
expression. Augmented expression of
ompS2
was also obtained upon addition of cloned
leuO
to the wild-type strain, but not in an
ompR
isogenic derivative, consistent with the notion that the transposon insertion had increased the cellular levels of LeuO and with the observed dependence on OmpR. Moreover, LeuO and OmpR bound in close proximity, but independently, to the 5′ upstream regulatory region. Thus, the OmpR and LeuO regulators positively regulate
ompS2
.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
46 articles.
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