Analysis of a Gene Cluster ofEnterococcus faecalisInvolved in Polysaccharide Biosynthesis

Abstract
Previously, we described a gene cluster ofEnterococcus faecalisOG1RF that produced an antigenic polysaccharide when cloned inEscherichia coli. The polysaccharide antigen was not detectable inE. faecalisstrains, however. Here, we show by reverse transcriptase-PCR that the 16 genes in this region are transcribed in OG1RF. Gene disruption oforfde4, encoding a putative glycosyl transferase, andorfde6, a putative dTDP-rhamnose biosynthesis gene, generated two OG1RF mutants. The mutants showed delayed killing and a higher 50% lethal dose in a mouse peritonitis model. In addition, two mucoidE. faecalisisolates from patients with chronic urinary tract infections were found to produce the polysaccharide antigen.