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Journal of Bacteriology, December 2000, p. 6762-6773, Vol. 182, No. 23
Department of Molecular Microbiology and
Immunology, Oregon Health Sciences University, Portland, Oregon
97201-3098
Received 18 April 2000/Accepted 24 July 2000
Products encoded in the trans-acting factor (TAF)
region are necessary for the biosynthesis of anguibactin and for
maximal expression of iron transport and biosynthesis genes in the
plasmid-encoded iron-scavenging system of Vibrio
anguillarum. Here we identify angB, a locus located
in the TAF region, which encodes products essential for anguibactin
biosynthesis. We demonstrate that a 287-amino-acid polypeptide, encoded
by angB and designated AngB, has an isochorismate lyase
activity necessary for the synthesis of 2,3-dihydroxybenzoic acid, an
anguibactin biosynthesis intermediate. Complementation of various
angB mutations provided evidence that an additional,
overlapping gene exists at this locus. This second gene, designated
angG, also has an essential biosynthetic function. The
angG gene directs the expression of three polypeptides when overexpressed in Escherichia coli, all of which are
translated in the same frame as AngB. The results of site-directed
mutagenesis and in vivo phosphorylation experiments suggest that the
carboxy-terminal end of AngB and the AngG polypeptide(s) function as
aryl carrier proteins involved in the assembly of the anguibactin
molecule. Our results also show that the regulatory functions of the
TAF are encoded in a region, TAFr, which is distinct from and
independent of the angB and angG genes.
0021-9193/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
The Overlapping angB and angG Genes Are
Encoded within the trans-Acting Factor Region of the
Virulence Plasmid in Vibrio anguillarum: Essential
Role in Siderophore Biosynthesis
*
Corresponding author. Mailing address: Department of
Molecular Microbiology and Immunology, Oregon Health Sciences
University, 3181 Sam Jackson Park Rd., Portland, OR 97201-3098. Phone:
(503) 494-7583. Fax: (503) 494-6862. E-mail:
crosajor{at}ohsu.edu.
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