Oligopeptide Permease A5 Modulates Vertebrate Host-Specific Adaptation of Borrelia burgdorferi

Abstract

Borrelia burgdorferi, the agent of Lyme disease, undergoes rapid adaptive gene expression in response to signals unique to its arthropod vector or vertebrate hosts. Among the upregulated genes under vertebrate host conditions is one of the five annotated homologs of oligopeptide permease A (OppA5, BBA34). A mutant lacking oppA5 was constructed in an lp25-deficient isolate of B. burgdorferi strain B31, and the minimal regions of infectivity were restored via a shuttle vector pBBE22 with or without an intact copy of bba34. Immunoblot analysis of the bba34 mutant revealed a reduction in the levels of RpoS, BosR, and CsrA Bb with a concomitant reduction in the levels of OspC, DbpA, BBK32, and BBA64. There were no changes in the levels of OspA, NapA, P66, and three other OppA orthologs. Quantitative transcriptional analysis correlated with the changes in the protein levels. However, the bba34 mutant displayed comparable infectivities in the C3H/HeN mice and the wild-type strain, despite the reduction in several pathogenesis-related proteins. Supplementation of the growth medium with increased levels of select components, notably sodium acetate and sodium bicarbonate, restored the levels of several proteins in the bba34 mutant to wild-type levels. We speculate that the transport of acetate appears to contribute to the accumulation of key metabolites, like acetyl phosphate, that facilitate the adaptation of B. burgdorferi to the vertebrate host by the activation of the Rrp2-RpoN-RpoS pathway. These studies underscore the importance of solute transport to host-specific adaptation of B. burgdorferi.

Contributions of Environmental Signals and Conserved Residues to the Functions of Carbon Storage Regulator A of Borrelia burgdorferi

“…This hypothesis is based on several lines of evidence. For example, we noted that when oppA5 was deleted, there was a reduction in the levels of CsrA Bb , RpoS, and several members of the rpoS regulon (33). Under conditions favoring increased levels of OppA5, we observed increased levels of those regulators and the opposite was true when CsrA Bb was deleted, suggesting a potential link between the functions of CsrA Bb and OppA5 (29).…”

“…It is also interesting that there could be a potential feedback loop connecting the levels of CsrA Bb , OppA5, and Pta (27,29,33). This hypothesis is based on several lines of evidence.…”

“…Moreover, levels of supplemental acetate in the borrelial growth medium impact the levels of CsrA Bb (27). In addition, increased levels of acetate also upregulated a solute binding protein, OppA5 (BBA34), in B. burgdorferi and restored levels of RpoS in an oppA5 mutant, presumably via increased transport of acetate, with a concomitant increase in levels of acetyl phosphate (33). It is unclear if the levels of CsrA Bb alone or the levels of available acetate contribute to the activation of the Rrp2-RpoN-RpoS pathway.…”

Competitive Advantage of Borrelia burgdorferi with Outer Surface Protein BBA03 during Tick-Mediated Infection of the Mammalian Host

“…One of the most highly conserved plasmids, which also has one of the largest proportions of differentially regulated genes in the B. burgdorferi genome, is the linear plasmid lp54 (7,10,21,30,32,39,40,44,51,52,56). Although several genes on lp54 have been identified as contributing to (5,14,41,48) or essential for (3,39,58) spirochete fitness in vivo, the majority of the proteins encoded on this plasmid are of unknown function and lack homologs in other organisms (9,15). We previously used the Cre-lox system to delete the genes encompassing a 4.1-kb region of lp54, from bba01 to bba07 (bba01-bba07 region) (A3⌬A1-7 mutant) (4).…”

BB0172, a Borrelia burgdorferi Outer Membrane Protein That Binds Integrin α 3 β 1

“…Polyclonal mouse anti-SodA and rabbit antiBosR sera were used as controls of cytoplasm-located proteins (44). The blots were developed following incubation with appropriate dilutions of horseradish peroxidase (HRP)-conjugated secondary antibodies and using enhanced chemiluminescence Western blotting reagents (GE Healthcare, Piscataway, NJ) as previously described (25,26,44,45).…”