OUTER SURFACE-PROTEINS E AND F OF BORRELIA-BURGDORFERI THE AGENT OF LYME-DISEASE

We report the cloning and characterization of two outer surface protei ns (Osps), designated OspE and OspF, from strain N40 of Borrelia burgd orferi, the spirochetal agent of Lyme disease. The ospE and ospF genes are structurally arranged in tandem as one transcriptional unit under the control of a common promoter. The ospE gene, located at the 5' en d of the operon, is 513 nucleotides in length and encodes a 171-amino- acid protein with a calculated molecular mass of 19.2 kDa. The ospF ge ne, located 27 bp downstream of the stop codon of the ospE gene, consi sts of 690 nucleotides and encodes a protein of 230 amino acids with a calculated molecular mass of 26.1 kDa. Pulsed-held gel electrophoresi s showed that the ospE and ospF genes are located on a 45-kb plasmid. Comparison of the leader sequences of OspE and OspF with those of the four known B. burgdorferi Osps (OspA, OspB, OspC, and OspD) reveals a hydrophobic domain and a consensus cleavage sequence (L-X-Y-C) recogni zed by signal peptidase II, and [H-3]palmitate labeling shows that Osp E and OspF are lipoproteins. Immunofluorescence studies demonstrated t hat both the OspE and OspF proteins are surface exposed. These feature s are consistent with the finding that OspE and OspF are B. burgdorfer i surface lipoproteins.