| Abstract [eng] |
One of the most abundant RNA sulfur modifications in bacteria is 4-thiouridine (s4U), commonly located at position 8 within tRNA molecules. This modification acts as a UV sensor and contributes to the thermodynamic stability of tRNA. Previous research revealed that a family of widespread bacterial proteins TudS act as thiouracil desulfidases; however, the specificity of TudS and the function of another widespread TudS-DUF1722 (RudS) fusion protein remained elusive. In this thesis, TudS and RudS were biochemically characterized, suggesting their physiological roles in thiomodified nucleotide recycling and bacterial UV-stress response. Additionally, the previously uncharacterized Domain of Unknown Function 1722 (DUF1722) within RudS was proposed to have a tRNA-binding function. The widespread prokaryotic stand-alone TudS domain proteins were identified as 4-thio-UMP desulfidases, contributing to the understudied field of modified nucleotide catabolism. Moreover, it was demonstrated that TudS supports bacterial growth by utilizing exogenous 4-thiouracil-containing compounds as uracil sources, some toxic to bacteria, thereby concurrently detoxifying their environment. RudS, a fusion protein containing TudS and DUF1722 domains, was identified as a tRNA 4-thiouridine de-modifying enzyme. Proof‑of‑concept experiments conducted in this study indicated that RudS is involved in the prokaryotic UV-stress response and may contribute to bacterial adaptation to UV radiation. |
