Publications

• TtcA a new tRNA-thioltransferase with an Fe-S cluster.

  Bouvier D., Labessan N., Clemancey M., Latour J.M., Ravanat J.L., Fontecave M., Atta M.

  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 clu ... >> More

  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. << Less

  Nucleic Acids Res. 42:7960-7970(2014) [PubMed] [EuropePMC]

• The conserved Cys-X1-X2-Cys motif present in the TtcA protein is required for the thiolation of cytidine in position 32 of tRNA from Salmonella enterica serovar Typhimurium.

  Jaeger G., Leipuviene R., Pollard M.G., Qian Q., Bjoerk G.R.

  The modified nucleoside 2-thiocytidine (s(2)C) has so far been found in tRNA from organisms belonging to the phylogenetic domains Archaea and Bacteria. In the bacteria Escherichia coli and Salmonella enterica serovar Typhimurium, s(2)C is present in position 32 of only four tRNA species-, and. An ... >> More

  The modified nucleoside 2-thiocytidine (s(2)C) has so far been found in tRNA from organisms belonging to the phylogenetic domains Archaea and Bacteria. In the bacteria Escherichia coli and Salmonella enterica serovar Typhimurium, s(2)C is present in position 32 of only four tRNA species-, and. An in-frame deletion of an S. enterica gene (designated ttcA, for "two-thio-cytidine") was constructed, and such a mutant has no detectable s(2)C in its tRNA. The TtcA protein family is characterized by the existence of both a PP-loop and a Cys-X(1)-X(2)-Cys motif in the central region of the protein but can be divided into two distinct groups based on the presence and location of additional Cys-X(1)-X(2)-Cys motifs in terminal regions of the sequence. Mutant analysis showed that both cysteines in this central conserved Cys-X(1)-X(2)-Cys motif are required for the formation of s(2)C. The DeltattcA1 mutant grows at the same rate as the congenic wild-type strain, and no growth disadvantage caused by the lack of s(2)C was observed in a mixed-population experiment. Lack of s(2)C32 did not reduce the selection rate at the ribosomal aminoacyl-tRNA site (A-site) for at any of its cognate CGN codons, whereas A-site selection at AGG by was dependent on the presence of s(2)C32. The presence of s(2)C32 in peptidyl- or in peptidyl-interfered with decoding in the A-site. The presence of s(2)C32 in decreased the rate of translation of the CGA codon but not that of the CGU codon. << Less

  J. Bacteriol. 186:750-757(2004) [PubMed] [EuropePMC]