title: Evidence for horizontal transfer from Streptococcus to Escherichia coli of the kfiD gene encoding the K5-specific UDP-glucose dehydrogenase.
abstract: Capsular polysaccharides are important virulence factors both in Gram-positive and Gram-negative bacteria. A similar cluster organization of the genes involved in the synthesis of bacterial exopolysaccharides has been postulated in both cases, suggesting that these clusters evolved by module assembly. Horizontal gene transfer has been postulated to explain the polymorphism found in these cellular polymers. The cap1 K and cap3A genes coding for the pneumococcal type 1 and type 3 UDP-glucose dehydrogenases, respectively, have been compared with other UDP-sugar dehydrogenases. We have observed that the evolutionary distance between Cap1K and Cap3A is approximately equal to that found between Cap1K (or Cap3A) and other UDP-GlcDH of families evolutionarily distant like KfiD, the dehydrogenase from Escherichia coli K5. On the basis of comparisons of G + C content, patterns of synonymous and nonsynonymous substitutions, dinucleotide frequencies, and codon usage bias, we conclude that the kfiD gene has been introduced into E. coli from an exogenous source, probably from a streptococcal species.
authors.affiliation: Departamento de Microbiología Molecular, CSIC, Madrid, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Muñoz
authors.forename: E
authors.initials: E
authors.lastname: García
authors.forename: R
authors.initials: R
authors.lastname: López
mesh_terms: D016667:Bacterial Capsules; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003062:Codon / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D005798:Genes, Bacterial; D005810:Multigene Family; D010802:Phylogeny; D011135:Polysaccharides, Bacterial; D013045:Species Specificity; D013291:Streptococcus / Q000201:enzymology* / Q000235:genetics*; D013379:Substrate Specificity; D014533:Uridine Diphosphate Glucose Dehydrogenase / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D003062:Codon; D029968:Escherichia coli Proteins; D011135:Polysaccharides, Bacterial; C050673:capsular polysaccharide K5; C081697:Cap3a protein, Streptococcus pneumoniae; C097522:KfiD protein, E coli; D014533:Uridine Diphosphate Glucose Dehydrogenase