Cloning, sequencing and characterisation of a Listeria monocytogenes gene encoding a fibronectin-binding protein

Listeria monocytogenes is a gram-positive, non-sporulating food-borne pathogen of man and animals that is able to invade many eukaryotic cells. L. monocytogenes possesses several proteins that bind fibronectin. In this study, an L. monocytogenes DNA library in pUC19 was screened with fibronectin and a gene encoding a 24.6-kDa fibronectin-binding protein (Fbp) was isolated and sequenced. Transcripts of the fbp gene were found in wild-type, in deltaprfA, and PrfA-S183A strains, despite the presence of a 'PrfA-like' box around its ribosome-binding site. The fbp gene was found to be present in all tested isolates of the species L. monocytogenes and a homologous DNA fragment was amplified in L. welshimeri. No homologies between the fbp gene and its translation product with any other DNA or proteins deposited in databanks were found. Restriction endonuclease-PCR (RE-PCR) showed that the fbp gene displays a degree of allelic variation among isolates of L. monocytogenes, whereas the corresponding amplified fragment of L. welshimeri seems to be monomorphic among isolates of this species. RE-PCR with Hha I, Dde I or Taq I produced DNA banding profiles specific for each of these two species, allowing their identification.