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Infection and Immunity, May 2001, p. 2829-2837, Vol. 69, No. 5
Department of Microbiology and Immunology,
University of Kentucky, Lexington, Kentucky
Received 5 October 2000/Returned for modification 12 January
2001/Accepted 30 January 2001
In Yersinia pestis, the causative agent of plague, two
inorganic iron transport systems have been partially characterized. The
yersiniabactin (Ybt) system is a siderophore-dependent transport system
required for full virulence. Yfe is an ABC transport system that
accumulates both iron and manganese. We have identified and cloned a
Y. pestis yfuABC operon. The YfuABC system is a member of
the cluster of bacterial ABC iron transporters that include Sfu of
Serratia, Hit of Haemophilus, and Yfu of
Yersinia enterocolitica. The Y. pestis KIM6+
system is most homologous to that in Y. enterocolitica, showing identities of 84% for YfuA (periplasmic binding protein), 87%
for YfuB (inner membrane permease), and 75% for YfuC (ATP hydrolase).
We constructed a yfuABC promoter-lacZ fusion to
examine regulation of transcription. This promoter contains a potential Fur binding sequence and is iron and Fur regulated. Significant expression from the yfuABC promoter occurred during
iron-deficient growth conditions. In vitro transcription and
translation of a recombinant plasmid encoding yfuABC
indicates that YfuABC proteins are expressed. Escherichia
coli 1017 (an enterobactin-deficient mutant) carrying this
plasmid was able to grow in an iron-restrictive complex medium. We
constructed a deletion encompassing the yfuABC promoter and
most of yfuA. This mutation was introduced into strains with mutations in Ybt, Yfe, or both systems to examine the role of Yfu
in iron acquisition in Y. pestis. Growth of the
yfu mutants in a deferrated, defined medium (PMH2) at 26 and 37°C failed to identify a growth or iron transport defect due to
the yfu mutation. Fifty percent lethal dose studies in mice
did not demonstrate a role for the Yfu system in mammalian virulence.
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.67.5.2829-2837.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Characterization of the Yersinia pestis
Yfu ABC Inorganic Iron Transport System
*
Corresponding author. Mailing address: Department of
Microbiology and Immunology, MS415 Medical Center, University of
Kentucky, Lexington, KY 40536-0298. Phone: (859) 323-6341. Fax: (859)
257-8994. E-mail: rperry{at}pop.uky.edu.
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