title: The Burkholderia cepacia bceA gene encodes a protein with phosphomannose isomerase and GDP-D-mannose pyrophosphorylase activities.
abstract: The bceA gene is part of the Burkholderia cepacia IST408 exopolysaccharide (EPS) biosynthetic cluster. It encodes a 55.3-kDa bifunctional protein (type II PMI family) with phosphomannose isomerase (PMI) and GDP-mannose pyrophosphorylase (GMP) activities. GMP activity is strongly dependent on the presence of Ca(2+) or Mn(2+), while PMI activity can use a broader variety of divalent cations (Ca(2+)>Mn(2+)>Mg(2+)>Co(2+)>Ni(2+)). The lack of a functional bceA gene does not affect EPS production yield in a non-polar insertion bceA mutant. The in silico search for putative bceA homologues revealed the presence of 2-5 bceA orthologues in the Burkholderia genomes available. This suggests that in B. cepacia IST408 putative bceA functional homologues may compensate the bceA mutation. However, the viscosity of aqueous solutions prepared with the EPS produced by the bceA mutant was significantly reduced compared with wild-type biopolymer and the mutant forms biofilms with a size reduced by 6-fold.
authors.affiliation: IBB-Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
authors.forename: Sílvia A
authors.initials: SA
authors.lastname: Sousa
authors.forename: Leonilde M
authors.initials: LM
authors.lastname: Moreira
authors.forename: Julia
authors.initials: J
authors.lastname: Wopperer
authors.forename: Leo
authors.initials: L
authors.lastname: Eberl
authors.forename: Isabel
authors.initials: I
authors.lastname: Sá-Correia
authors.forename: Jorge H
authors.initials: JH
authors.lastname: Leitão
mesh_terms: D016956:Burkholderia cepacia / Q000201:enzymology* / Q000235:genetics*; D004789:Enzyme Activation; D008359:Mannose-6-Phosphate Isomerase / Q000235:genetics* / Q000378:metabolism*; D009713:Nucleotidyltransferases / Q000235:genetics* / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics
chemical_list: D009713:Nucleotidyltransferases; C026917:mannose 1-phosphate guanylyltransferase; D008359:Mannose-6-Phosphate Isomerase