Borrelia burgdorferi 297 bmpA encode the mRNA that contains ORF for a leader peptide that regulates bmpA gene expression.

Abstract

The Bmp proteins are highly conserved proteins with no well established functions in B. burgdorferi sensu lato and are immunogenic. It was reported that four genes from this cluster bmpD-bmpC-bmpA-bmpB are expressed in vitro as monocistronic and polycistronic messages.Evidence is presented in this report that bmpA mRNA contains two ribosome binding sites (SD) separated by 90 bases pairs. The SD1 precedes a small 32 amino acid ORF -leader peptide (BmpAL). The SD2 is the RBS for 342 amino acids BmpA. The bmpAL and bmpA ORFs in B.burgdorferi 297 overlap by eight base pairs suggesting that two proteins can be co-regulated. First five codons in the leader peptide and "-GGG-" in SD2 are rarely used in Borrelia, suggesting that they can regulate BmpAL and BmpA expression. Deletion of SD1 in the leader sequence, or introducing a stop codon immediately before SD2 leads to increased BmpA::GFP expression in B.burgdorferi 297 that contains bmpA::gfp translational fusion on the plasmid. In B. garinii G25 and B. afzelii IP3 the leader sequence is in frame with bmpA, and a result, in B. afzelii IP3 BmpA are expressed as the higher molecular weight protein compared to BmpA of B. burgdorferi 297 and B. afzelii DK7.