The pap Operon of Avian Pathogenic Escherichia coli Strain O1:K1 Is Located on a Novel Pathogenicity Island

Abstract
We have identified a 56-kb pathogenicity island (PAI) in avian pathogenic Escherichia coli strain O1:K1 (APEC-O1). This PAI, termed PAI I APEC-O1 , is integrated adjacent to the 3′ end of the pheV tRNA gene. It carries putative virulence genes of APEC ( pap operon), other E. coli genes ( tia and ireA ), and a 1.5-kb region unique to APEC-O1. The kps gene cluster required for the biosynthesis of polysialic acid capsule was mapped to a location immediately downstream of this PAI.