Expression and Mutational Analysis of DinB-Like Protein DR0053 in <i>Deinococcus radiodurans</i>

<div><p>In order to understand the mechanism governing radiation resistance in <i>Deinococcus radiodurans</i>, current efforts are aimed at identifying potential candidates from a large repertoire of unique Deinococcal genes and protein families. DR0053 belongs to the DinB/YfiT protein family, which is an over-represented protein family in <i>D. radiodurans</i>. We observed that <i>dr0053</i> transcript levels were highly induced in response to gamma radiation (γ-radiation) and mitomycin C (MMC) exposure depending on PprI, RecA and the DrtR/S two-component signal transduction system. Protein profiles demonstrated that DR0053 is a highly induced protein in cultures exposed to 10 kGy γ-radiation. We were able to determine the transcriptional start site of <i>dr0053</i>, which was induced upon irradiation, and to assign the 133-bp promoter region of <i>dr0053</i> as essential for radiation responsiveness through primer extension and promoter deletion analyses. A <i>dr0053</i> mutant strain displayed sensitivity to γ-radiation and MMC exposure, but not hydrogen peroxide, suggesting that DR0053 helps cells recover from DNA damage. Bioinformatic analyses revealed that DR0053 is similar to the <i>Bacillus subtilis</i> protein YjoA, which is a substrate of bacterial protein-tyrosine kinases. Taken together, the DNA damage-inducible (<i>din</i>) gene <i>dr0053</i> may be regulated at the transcriptional and post-translational levels.</p>