The role of the Borrelia oxidative stress regulator protein in virulence gene expression of the Lyme disease spirochete

Abstract

The Lyme disease agent, Borrelia burgdorferi, has a complex system that allows it to thrive in the harsh and distinct environments of its tick vector and mammalian host. Although it has been known for some time that the Borrelia oxidative stress regulator protein (BosR) plays a necessary role in mammalian infectivity and functions as a transcriptional regulator of alternative sigma factor RpoS, very little is known about its mechanism of action, other than the suggestion that BosR activates rpoS transcription by binding to certain upstream regions of the gene. In our studies, we performed protein degradation assays and luciferase reporter assays for further understanding of BosR function. Our preliminary findings suggest that BosR is post-transcriptionally regulated by an unknown protease and may not need to bind to any rpoS upstream regions in order to activate transcription. We also describe the construction of luciferase reporter systems that will shed light on BosR’s mechanism of action. We postulate the provocative possibility that unlike its homologs Fur and PerR in other bacterial systems, BosR may not utilize a DNA-binding mechanism in order to fulfill its role as a transcriptional regulator to modulate virulence gene expression.