| Literature DB >> 22166682 |
Sunna Helgadóttir1, Sylvie Sinapah, Dieter Söll, Jiqiang Ling.
Abstract
In methanogenic archaea, Sep-tRNA:Cys-tRNA synthase (SepCysS) converts Sep-tRNA(Cys) to Cys-tRNA(Cys). The mechanism of tRNA-dependent cysteine formation remains unclear due to the lack of functional studies. In this work, we mutated 19 conserved residues in Methanocaldococcus jannaschii SepCysS, and employed an in vivo system to determine the activity of the resulting variants. Our results show that three active-site cysteines (Cys39, Cys42 and Cys247) are essential for SepCysS activity. In addition, combined with structural modeling, our mutational and functional analyses also reveal multiple residues that are important for the binding of PLP, Sep and tRNA. Our work thus represents the first systematic functional analysis of conserved residues in archaeal SepCysSs, providing insights into the catalytic and substrate binding mechanisms of this poorly characterized enzyme.Entities:
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Year: 2011 PMID： 22166682 PMCID： PMC4712913 DOI： 10.1016/j.febslet.2011.11.024
Source DB: PubMed Journal: FEBS Lett ISSN： 0014-5793 Impact factor: 4.124