Identification of the lic1ABCD operon that controls the phase-variable expression of phosphorylcholine on lipopolysaccharide from Avibacterium paragallinarum.

Identification of the lic1ABCD operon that controls the phase-variable expression of phosphorylcholine on lipopolysaccharide from Avibacterium paragallinarum. Avian Pathol. 2013 Feb;42(1):72-8 Authors: Chiang YT, Shien JH, Tan DH, Shieh MK, Liu CC, Chen YS, Chang PC Abstract Phosphorylcholine (ChoP) is an important virulence factor found on the surface of many mucosal pathogens and its expression enhances bacterial colonization on mucous membranes and reduces susceptibility to antimicrobial peptides. Whole-genome sequencing analyses showed that Avibacterium paragallinarum contained an operon with strong sequence similarity to the lic1ABCD operon from Haemophilus influenzae and the pcgDABC operon from Pasteurella multocida; both operons are involved in metabolism and addition of ChoP on bacterial lipopolysaccharide (LPS). Western immunoblot analysis with ChoP-specific monoclonal antibody showed that ChoP is present on LPS of Av. paragallinarum and the expression of ChoP is controlled by phase variation mediated by the number of 5'-CAAT-3' tetranucleotide tandem repeats within the coding region of the lic1A gene. The number of tetranucleotide repeats varied widely among strains, and variation in the number of repeats was observed following in vivo passage but not in vitro passage. Antimicrobial susceptibility assays showed that ChoP expression decreased susceptibility of Av. paragallinarum to chicken antimicrobial peptide fowlicidin-1. This is t...
Source: Avian Pathology - Category: Pathology Authors: Tags: Avian Pathol Source Type: research