[1P-24(WS2-4)] tRNA thiolation mechanism catalyzed by iron-sulfur enzymes
tRNA undergoes maturation processes including base modification, then becomes functional. About 100 kinds of base modifications have been found such as thiolation which abnormalities induce mitochondrial disease and cancer.
tRNA thiolation is catalyzed by 2-thiouridine synthase TtuA with the sulfur donor protein, TtuB. Recently, our structural, spectroscopic, and biochemical analyses have shown that [4Fe-4S] cluster is essential for the activity of TtuA and the one iron (unique Fe) binds to TtuB. However, the function of the unique Fe and how tRNA receives sulfur from TtuB are unclear. Meanwhile, 2-thiouridine synthase Ncs6 which is a TtuA homolog catalyzing tRNA thiolation together with Urm1 similar to TtuA-TtuB has been reported to have [3Fe-4S] even the structure of [4Fe-4S]-Ncs6 has been determined.
In this study, we revealed the relationship between the structure of Fe-S clusters of TtuA and its activity under the strictly controlled redox. We also found that the unique Fe directly captures sulfur from TtuB after tRNA activation, and identified key residues of the enzymes. Taking all results together, we propose the detailed tRNA thiolation mechanism involved in Fe-S clusters.
tRNA thiolation is catalyzed by 2-thiouridine synthase TtuA with the sulfur donor protein, TtuB. Recently, our structural, spectroscopic, and biochemical analyses have shown that [4Fe-4S] cluster is essential for the activity of TtuA and the one iron (unique Fe) binds to TtuB. However, the function of the unique Fe and how tRNA receives sulfur from TtuB are unclear. Meanwhile, 2-thiouridine synthase Ncs6 which is a TtuA homolog catalyzing tRNA thiolation together with Urm1 similar to TtuA-TtuB has been reported to have [3Fe-4S] even the structure of [4Fe-4S]-Ncs6 has been determined.
In this study, we revealed the relationship between the structure of Fe-S clusters of TtuA and its activity under the strictly controlled redox. We also found that the unique Fe directly captures sulfur from TtuB after tRNA activation, and identified key residues of the enzymes. Taking all results together, we propose the detailed tRNA thiolation mechanism involved in Fe-S clusters.