A tRNA-dependent cysteine biosynthesis enzyme recognizes the selenocysteine-specific tRNA in Escherichia coli

作者：Yuan Jing; Hohn Michael J; Sherrer R Lynn; Palioura Sotiria; Su Dan; Soell Dieter

来源：FEBS Letters, 2010, 584(13): 2857-2861.

DOI：10.1016/j.febslet.2010.05.028

• Aminoacyl-tRNA
• Formate dehydrogenase
• Selenocysteine
• O-phosphoseryl-tRNA(Sec) kinase
• Sep-tRNA:Cys-tRNA synthase
• Sep-tRNA:Sec-tRNA synthase

The essential methanogen enzyme Sep-tRNA:Cys-tRNA synthase (SepCysS) converts O-phosphoseryl-tRNA(Cys) (Sep-tRNA(Cys)) into Cys-tRNA(Cys) in the presence of a sulfur donor. Likewise, Sep-tRNA:Sec-tRNA synthase converts O-phosphoseryl-tRNA(Sec) (Sep-tRNA(Sec)) to selenocysteinyl-tRNA(Sec) (Sec-tRNA(Sec)) using a selenium donor. While the Sep moiety of the aminoacyl-tRNA substrates is the same in both reactions, tRNA(Cys) and tRNA(Sec) differ greatly in sequence and structure. In an Escherichia coli genetic approach that tests for formate dehydrogenase activity in the absence of selenium donor we show that Sep-tRNA(Sec) is a substrate for SepCysS. Since Sec and Cys are the only active site amino acids known to sustain FDH activity, we conclude that SepCysS converts Sep-tRNA(Sec) to Cys-tRNA(Sec), and that Sep is crucial for SepCysS recognition.

• 出版日期2010-7-2