TtcA，一种带有铁硫簇的新型tRNA硫转移酶。

Bouvier Denis, Labessan Natty, Clémancey Martin, Latour Jean-Marc, Ravanat Jean-Luc, Fontecave Marc, Atta Mohamed

University of Grenoble Alpes, iRTSV-LCBM, UMR5249, F-38000 Grenoble, France CNRS, iRTSV-LCBM, UMR5249, F-38000 Grenoble, France CEA, iRTSV-LCBM, UMR5249, F-38000 Grenoble, France.

University of Grenoble Alpes, INAC, SCIB, F-38000 Grenoble, France CEA, iNAC, SCIB, F-38054 Grenoble, France.

Nucleic Acids Res. 2014 Jul;42(12):7960-70. doi: 10.1093/nar/gku508. Epub 2014 Jun 9.

TtcA catalyzes the post-transcriptional thiolation of cytosine 32 in some tRNAs. The enzyme from Escherichia coli was homologously overexpressed in E. coli. The purified enzyme is a dimer containing an iron-sulfur cluster and displays activity in in vitro assays. The type and properties of the cluster were investigated using a combination of UV-visible absorption, EPR and Mössbauer spectroscopy, as well as by site-directed mutagenesis. These studies demonstrated that the TtcA enzyme contains a redox-active and oxygen-sensitive [4Fe-4S] cluster, chelated by only three cysteine residues and absolutely essential for activity. TtcA is unique tRNA-thiolating enzyme using an iron-sulfur cluster for catalyzing a non-redox reaction.

TtcA催化某些tRNA中胞嘧啶32的转录后硫醇化反应。来自大肠杆菌的该酶在大肠杆菌中进行了同源过表达。纯化后的酶是一种含有铁硫簇的二聚体，并且在体外试验中表现出活性。使用紫外可见吸收光谱、电子顺磁共振光谱和穆斯堡尔光谱相结合的方法，以及定点诱变技术，对该簇的类型和性质进行了研究。这些研究表明，TtcA酶含有一个对氧化还原有活性且对氧敏感的[4Fe-4S]簇，该簇仅由三个半胱氨酸残基螯合，并且对于活性来说是绝对必需的。TtcA是一种独特的tRNA硫醇化酶，它利用铁硫簇催化一个非氧化还原反应。