Borrelia burgdorferi SpoVG DNA- and RNA-Binding Protein Modulates the Physiology of the Lyme Disease Spirochete

Abstract

The SpoVG protein of <i>Borrelia burgdorferi</i>, the Lyme disease spirochete, binds to specific sites of DNA and RNA. The bacterium regulates transcription of <i>spoVG</i> during the natural tick-mammal infectious cycle and in response to some changes in culture conditions. Bacterial levels of <i>spoVG</i> mRNA and SpoVG protein did not necessarily correlate, suggesting that posttranscriptional mechanisms also control protein levels. Consistent with this, SpoVG binds to its own mRNA, adjacent to the ribosome-binding site. SpoVG also binds to two DNA sites in the <i>glpFKD</i> operon and to two RNA sites in <i>glpFKD</i> mRNA; that operon encodes genes necessary for glycerol catabolism and is important for colonization in ticks. In addition, spirochetes engineered to dysregulate <i>spoVG</i> exhibited physiological alterations.<b>IMPORTANCE</b><i>B. burgdorferi</i> persists in nature by cycling between ticks and vertebrates. Little is known about how the bacterium senses and adapts to each niche of the cycle. The present studies indicate that <i>B. burgdorferi</i> controls production of SpoVG and that this protein binds to specific sites of DNA and RNA in the genome and transcriptome, respectively. Altered expression of <i>spoVG</i> exerts effects on bacterial replication and other aspects of the spirochete's physiology.