Infection and Immunity, July 1999, p. 3525-3532, Vol. 67, No. 7
0019-9567/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Channing Laboratory,
Received 9 December 1998/Returned for modification 23 February
1999/Accepted 6 April 1999
A major clinical manifestation of infection with Bacteroides
fragilis is the formation of intra-abdominal abscesses, which are
induced by the capsular polysaccharides of this organism. Transposon
mutagenesis was used to locate genes involved in the synthesis of
capsular polysaccharides. A 24,454-bp region was sequenced and found to
contain a 15,379-bp locus (designated wcf) with 16 open
reading frames (ORFs) encoding products similar to those encoded by
genes of other bacterial polysaccharide biosynthesis loci. Four genes
encode products that are similar to enzymes involved in nucleotide
sugar biosynthesis. Seven genes encode products that are similar to
sugar transferases. Two gene products are similar to
O-acetyltransferases, and two products are probably involved in polysaccharide transport and polymerization. The product of
one ORF, WcfH, is similar to a set of deacetylases of the NodB family.
Deletion mutants demonstrated that the wcf locus is
necessary for the synthesis of polysaccharide B, one of the two
capsular polysaccharides of B. fragilis 9343. The virulence
of the polysaccharide B-deficient mutant was comparable to that of the
wild type in terms of its ability to induce abscesses in a rat model of
intra-abdominal infection.
*
Corresponding author. Mailing address: Channing
Laboratory, 181 Longwood Ave., Boston, MA 02115. Phone: (617) 525-2679. Fax: (617) 731-1541. E-mail:
lcomstock{at}channing.harvard.edu.
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