Schematic of the bosR-containing operon and screening of bosR::kanR mutant, JH300, in B. burgdorferi. A. The schematic depicts the chromosomal region of B. burgdorferi containing bosR and the genetic disruption of bosR with the insertion of PflgB-kanR resulting in strain JH300. The arrows indicate the location of oligonucleotide primers utilized to screen clones for presence of kanR cassette. B. PCR screen of JH300 was performed using primers specific for bosR that amplified a 586 bp product in ML23 or an approximate 2.5-kb product in JH300, indicating the insertion of PflgB-kanR. Lane 1: ML23; Lane 2: JH300. Markers (in bp) are shown on the left. C. BosR is not produced in strain JH300. Cultures were grown to 5 × 107/ml and cell lysates were resolved by SDS-PAGE, immobilized on PVDF membranes, and probed with antisera specific for BosR.