IDENTIFICATION OF bce CLUSTER II OF GENES INVOLVED IN THE BIOSYNTHESIS OF THE EXOPOLYSACCHARIDE CEPACIAN BY BACTERIA OF THE BURKHOLDERIA GENUS

Ana Sofia de Jesus Ferreira; Jorge Humberto Gomes Leitão; Sílvia Andreia Bento da Silva Sousa Barbosa; Isabel Maria de Sá Correia Leite de Almeida; Leonilde M. Moreira

Key information

Authors:

Ana Sofia de Jesus Ferreira (Ana Sofia de Jesus Ferreira); Jorge Humberto Gomes Leitão (Jorge Humberto Gomes Leitão); Sílvia Andreia Bento da Silva Sousa Barbosa (Sílvia Andreia Bento da Silva Sousa Barbosa); Isabel Maria de Sá Correia Leite de Almeida (Isabel Sá-Correia); Leonilde M. Moreira (Leonilde de Fátima Morais Moreira)

Published in

December 2007

Abstract

Burkholderia cepacia complex (Bcc) is a group of opportunistic pathogens associated with infections in cystic fibrosis patients. These bacteria produce exopolysaccharide (EPS). More than 80% of the Bcc isolates recovered from portuguese CF patients produce the EPS cepacian, a branched acetylated heptasaccharide repeat-unit with glucose, rhamnose, mannose, galactose and glucuronic acid in the ratio 1:1:1:3:1, respectively (1). A cluster of 11 genes (bceA-K) was identified previously (1) and encode glycosyltransferases, proteins involved in the formation of sugar nucleotides and in the polymerization/export/regulation of EPS production (1,2,3). Comparative genomics showed that the bce cluster is present in all Bcc strains sequenced so far, as well as in non Bcc strains such has B. pseudomallei, B. thailandensis or B. xenovorans. The analysis of the EPS gene cluster in non Bcc strains revealed 8 additional genes. In silico analysis of the Bcc genomes indicated that such region is present 150kb downstream of the bceK gene, and encodes 3 proteins putatively involved in sugar nucleotide biosynthesis, a glycosyltransferase, a polysaccharide transporter and 3 proteins of unknown function. Insertion mutants using B. cepacia IST408 as a model organism for EPS production are being constructed to evaluate the contribution of this region to cepacian biosynthesis. We propose this new genomic region as an extension to the bce gene cluster. 1-Moreira LM et al. Biochem Biophys Res Commun, 312: 323-333, 2003 3-Sousa SA et al. Biochem Biophys Res Commun, 353: 200-206, 2007 2-Ferreira AS et al. Appl Environ Microbiol, 73: 524-534, 2007