The BBA 33 lipoprotein binds collagen and impacts B orrelia burgdorferi pathogenesis

B orrelia burgdorferi , the etiologic agent of L yme disease, adapts to the mammalian hosts by differentially expressing several genes in the BosR and Rrp2‐RpoN‐RpoS dependent pathways, resulting in a distinct protein profile relative to that seen for survival in the Ixodes spp. tick. Previous studies indicate that a putative lipoprotein, BBA 33, is produced in an RpoS ‐dependent manner under conditions that mimic the mammalian component of the borrelial lifecycle. However, the significance and function for BBA 33 is not known. Given its linkage to the BosR/Rrp2‐RpoN‐RpoS regulatory cascade, we hypothesized that BBA 33 facilitates B . burgdorferi infection in the mammalian host. The deletion of bba33 eliminated B . burgdorferi infectivity in C 3 H mice, which was rescued by genetic complementation with intact bba33 . With regard to function, a combinatorial peptide approach, coupled with subsequent in vitro binding assays, indicated that BBA 33 binds to collagen type VI and, to a lesser extent, collagen type IV . Whole cell binding assays demonstrated BBA 33‐dependent binding to human collagen type VI . Taken together, these results suggest that BBA 33 interacts with collagenous structures and may function as an adhesin in a process that is required to prevent bacterial clearance.