Methanogens are members ofthe human microbiome and the only known source of biogenic methane. Residing in the third domain of life, Archaea, they are strict anaerobes that have evolved systems to combat periodic oxygen exposure. There is a signiflcant gap in our knowledge of how methanogens mount a transcriptional response that ultimafiey leads to cell survival during periods of oxygen stress. The overall goal of this project is to understand the role of MsvR in regulating the oxidative stress response in methanogenic Archaea through structure/funcfion analysis. MsvR is a newly described transcripfional regulator present in select methanogens including those residing within the human intesfine and oral cavity. Early characterization of MsvR has led to the development ofthe following hypotheses: HI) mulfiple amino acid residues in MsvR play a role in its funcfion as a transcriptional regulator, (H2) oxidized and reduced MsvR play disfinct yet integral roles in the regulafion of expression of at least two promoters, and (H3) MsvR undergoes various conformational changes when shifting between the oxidized and reduced states that impact its funcfion. To address these hypotheses the following specific aims are proposed:
(Aim 1) Determine the 3D structure of MsvR by X-ray crystallography, (Aim 2) Identify additional amino acid residues or combinafions thereof in MsvR necessary for funcfion, (Aim 3) Identiflcation of disulfide bonds formed upon oxidative stress and the role of oxidized vs. reduced MsvR in transcription regulafion, (Aim 4) Identificafion of conformational changes in MsvR.
As potentially secondary contributors to pathogenesis, it is critical to gain a better understanding of how methanogens withstand intermittent encounters with oxygen. Additionally these organisms likely possess very sensitive mechanisms to sense changes in cellular redox that may provide insight into subtle changes in redox balance that play a role in aging and disease.
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