Sequence characterization of two new members of a multi-gene family in Serpulina hyodysenteriae (B204) with homology to a 39 kDa surface exposed protein: vspC and D

Previous cloning and sequencing of clones from a genomic library constructe d from Serpulina hyodysenteriae B204 had identified a tandem pair of open r eading frames, identified as vspA and vspB (variable surface protein) expec ted to encode proteins with homology to (but not identical with) a 39 kDa s urface exposed membrane protein from this animal pathogen. Additional scree ning of the genomic library was performed to retrieve the remainder of the vspB gene using new oligonucleotide probes based upon the cloned gene seque nces. Not only was this goal met but we also discovered two more adjacent a nd related vsp genes (vspC and vspD) and have completely sequenced them. Th ey are all in a parallel orientation and appear to have a set of similar bu t distinct regulatory elements that may control separate expression of thei r open reading frames (ORFs). Thus, there are four contiguous vsp genes whi ch are predicted to encode a family of structurally conserved proteins. The four adjacent open reading frames (ORFs) are of similar size (384-389 codo ns) and share from 83% to 90% identity in their amino acid sequence. Prelim inary data suggests there may be yet another homologous gene copy in a dist al location of S. hyodysenteriae that faithfully encodes the 39 kDa surface protein. The organization and homologies of these highly conserved multipl e gene copies are discussed. (C) 1999 Elsevier Science B.V. All rights rese rved.