Molecular and genomic analysis of genes encoding surface-anchored proteins from Clostridium difficile

The gene slpA, encoding the S-layer precursor protein in the virulent Clostridium difficile strains C253 and 79--685, was identified. The precursor protein carries a C-terminal highly conserved anchoring domain, similar to the one found in the Cwp66 adhesin (previously characterized in strain 79--685), an SLH domain, and a variable N-terminal domain mediating cell adherence. The genes encoding the S-layer precursor proteins and the Cwp66 adhesin are present in a genetic locus carrying 17 open reading frames, 11 of which encode a similar two-domain architecture, likely to include surface-anchored proteins.