Affiliation:
1. Bacterial Pathogenesis Research Group, Department of Microbiology, Monash University, Victoria 3800,1 and
2. Department of Microbiology and Infectious Diseases, Royal Children's Hospital, Parkville, Victoria 3052,2 Australia
Abstract
ABSTRACT
Iron uptake systems which are critical for bacterial survival and which may play important roles in bacterial virulence are often carried on mobile elements, such as plasmids and pathogenicity islands (PAIs). In the present study, we identified and characterized a ferric dicitrate uptake system (Fec) in
Shigella flexneri
serotype 2a that is encoded by a novel PAI termed the
Shigella
resistance locus (SRL) PAI. The
fec
genes are transcribed in
S. flexneri
, and complementation of a
fec
deletion in
Escherichia coli
demonstrated that they are functional. However, insertional inactivation of
fecI
, leading to a loss in
fec
gene expression, did not impair the growth of the parent strain of
S. flexneri
in iron-limited culture media, suggesting that
S. flexneri
carries additional iron uptake systems capable of compensating for the loss of Fec-mediated iron uptake. DNA sequence analysis showed that the
fec
genes are linked to a cluster of multiple antibiotic resistance determinants, designated the SRL, on the chromosome of
S. flexneri
2a. Both the SRL and
fec
loci are carried on the 66,257-bp SRL PAI, which has integrated into the
serX
tRNA gene and which carries at least 22 prophage-related open reading frames, including one for a P4-like integrase. This is the first example of a PAI that carries genes encoding antibiotic resistance and the first report of a ferric dicitrate uptake system in
Shigella
.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
Cited by
105 articles.
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