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Infection and Immunity, February 2000, p. 526-534, Vol. 68, No. 2
Section of Clinical Immunology, Microbiology
and Virology, Department of Pathology, University of Utah, Salt
Lake City, Utah 84132
Received 3 August 1999/Returned for modification 9 September
1999/Accepted 3 November 1999
The ability of Vibrio vulnificus to acquire iron from
the host has been shown to correlate with virulence. Many iron
transport genes are regulated by iron, and in V. vulnificus, transcriptional regulation by iron depends on the
fur gene. The N-terminal amino acid sequence of a 72-kDa
iron-regulated outer membrane protein purified from a V. vulnificus fur mutant had 53% homology with the first 15 amino
acids of the mature protein of the Vibrio cholerae vibriobactin receptor, ViuA. In this report, we describe the cloning, DNA sequence, mutagenesis, and analysis of transcriptional regulation of the structural gene for VuuA, the vulnibactin receptor of V. vulnificus. Analysis of the DNA sequence of the vuuA
promoter region demonstrated a sequence identical to the upstream Fur
box of V. cholerae viuA. Northern blot analysis showed that
the transcript was strongly regulated by iron. The amino acid sequence
of VuuA was 74% identical to the sequence of V. cholerae
ViuA and was homologous to those of several TonB-dependent outer
membrane receptors. An internal deletion of the V. vulnificus
vuuA gene resulted in the loss of expression of the 72-kDa
protein and the loss of the ability to use transferrin or vulnibactin
as a source of iron. This mutant showed reduced virulence in an infant
mouse model. Introduction of a plasmid containing the complete
viuA coding sequence and 342 bp of upstream DNA into the
mutant restored ferric vulnibactin and ferric transferrin utilization
to the mutant.
0019-9567/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Cloning and Characterization of vuuA, a
Gene Encoding the Vibrio vulnificus Ferric Vulnibactin
Receptor
*
Corresponding author. Mailing address: Section of
Clinical Immunology, Microbiology and Virology, Department of
Pathology, University of Utah, Salt Lake City, Utah 84132. Phone: (801)
585-6864. Fax: (801) 581-4517. E-mail:
Christine_Litwin{at}hlthsci.med.utah.edu.
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