Exploring the role of a novel σ ^70 protein in Borrelia burgdorferi

The bacterium Borrelia burgdorferi is the causative agent of Lyme disease, the most common arthropod-borne disease in the Northern Hemisphere. This ailment affects 400,000 people annually, and can cause symptoms such as fever, joint stiffness, fatigue, carditis, and neurological issues. One of the most fundamental processes in any cell, including B. burgdorferi, is the transcription of DNA into an RNA messenger, which is later translated into proteins. Transcription is carried out by a multisubunit molecular complex called RNA polymerase, which is recruited onto the DNA strand and synthesizes RNA by reading the DNA. RpoD, also known as σ70, is the subunit of RNA polymerase in bacteria that recognizes the correct binding site on DNA. In all bacteria studied to date, the size of RpoD is 70 kilodaltons (kDa). Although the rpoD gene in B. burgdorferi appears to encode a 70-kDa subunit, two lines of evidence suggest that only a 50-kDa protein is produced in these bacteria. In order to biochemically dissect the function of this truncated RpoD in B. burgdorferi, I have overexpressed and purified it to near homogeneity using recombinant DNA methodologies. The putative RpoD protein was then assayed for transcriptional activity using an in vitro transcription assay. Future directions for this project would include obtaining a crystal structure of the truncated RpoD from B. burgdorferi and analyzing its regulation