Mutations in thef1651Aandf1651Efimbrial genes and regulation of their expression in anEscherichia colistrain causing septicemia in pigs

Abstract

Transposon (TnphoA) mutagenesis was used to study the expression of F1651fimbriae, related to Prs fimbriae, in the pathogenicEscherichia colistrain 5131 (O115K“V165”F165) This strain causes septicemia in swine and also expresses F1652fimbriae, related to F1C Adhesin-defective mutants from the wild-type pathogenic strain were produced and TnphoA insertions were localized either in thef1651Agene, which encodes the major fimbrial subunit or in thef1651E, gene, which encodes a minor fimbrial subunit TnphoAgene fusions were used to measure expression of F1651fimbrial genes Similar pattern of regulation of expression was observed in bothf1651A andf1651E genes Optimal expression of F1651fimbriae was obtained on solid minimal medium Production of F1651fimbriae was negatively regulated by addition of glucose, leucine or alanine to the media, by growth at 18°C, and by pH above or below 70