Investigation of the Role of Manganese Transport Repressor DR2539 in Mn/Fe Homeostasis

Abstract

Mn and Fe ions are necessary for fundamental cellular processes, where they serve as enzyme cofactors or impart structural stability to proteins. However, Mn and Fe are toxic in excess. For example, dysregulation of Mn/Fe homeostasis results in manganism, a neurological disorder with symptoms similar to Parkinson’s disease. Therefore, tight regulation of intracellular Mn/Fe ratios is critical. Understanding the mechanisms used to regulate Mn/Fe homeostasis has both medical and bioremediation implications. D. radiodurans is particularly successful at establishing maintaining a high Mn/Fe ratio, making it an ideal model to investigate. DR2539, a metal ion dependent transcription factor of the DtxR family, plays a major role in maintaining the intracellular ratio of manganese to iron within D. radiodurans. DR2539 has been shown to bind to the promoter of the Mn importer protein, MntH and repress it in a Mn‐ and Fe‐ dependent manner. 64 other genes are either up‐ or downregulated in the absence of functional DR2539. To further elucidate the role of DR2539 in Mn homeostasis, we recombinantly expressed DR2539 from E. coli and purified it to homogeneity. Preliminary differential light scattering (DLS) and differential scanning fluorimetry (DSF) results suggest DR2539 can bind to Mn, and Mn binding induced oligomerization of the protein. Comparative modeling suggest the Mn‐induced oligomer is either a homodimer or a homotetramer with a similar structure to other members of the DtxR family. Preliminary crystallization screening experiments have identified potential conditions which may lead to samples suitable for high‐resolution structural studies. In total these experiments represent a first step toward elucidating the molecular basis of DR2539 function.Support or Funding InformationNSF HRD 1547757 Grant