Ancient translation factor is essential for tRNA-dependent cysteine biosynthesis in methanogenic archaea.

ABSTRACT: Methanogenic archaea lack cysteinyl-tRNA synthetase; they synthesize Cys-tRNA and cysteine in a tRNA-dependent manner. Two enzymes are required: Phosphoseryl-tRNA synthetase (SepRS) forms phosphoseryl-tRNA(Cys) (Sep-tRNA(Cys)), which is converted to Cys-tRNA(Cys) by Sep-tRNA:Cys-tRNA synthase (SepCysS). This represents the ancestral pathway of Cys biosynthesis and coding in archaea. Here we report a translation factor, SepCysE, essential for methanococcal Cys biosynthesis; its deletion in Methanococcus maripaludis causes Cys auxotrophy. SepCysE acts as a scaffold for SepRS and SepCysS to form a stable high-affinity complex for tRNA(Cys) causing a 14-fold increase in the initial rate of Cys-tRNA(Cys) formation. Based on our crystal structure (2.8-Å resolution) of a SepCysS⋅SepCysE complex,

SUBMITTER: Liu Y 

PROVIDER: S-EPMC4115501 | biostudies-literature | 2014 Jul

REPOSITORIES: biostudies-literature