3WKR

Crystal structure of the SepCysS-SepCysE complex from Methanocaldococcus jannaschii

Summary for 3WKR

• Entry DOI: 10.2210/pdb3wkr/pdb
• Descriptor: O-phospho-L-seryl-tRNA:Cys-tRNA synthase, Uncharacterized protein MJ1481 (3 entities in total)
• Functional Keywords: aminoacyl trna synthesis, transferase
• Biological source: Methanocaldococcus jannaschii; More
• Total number of polymer chains: 8
• Total formula weight: 291036.44

Authors

Nakazawa, Y.,Asano, N.,Nakamura, A.,Yao, M. (deposition date: 2013-10-30, release date: 2014-07-16, Last modification date: 2022-08-24)

Primary citation

Liu, Y.,Nakamura, A.,Nakazawa, Y.,Asano, N.,Ford, K.A.,Hohn, M.J.,Tanaka, I.,Yao, M.,Soll, D.
Ancient translation factor is essential for tRNA-dependent cysteine biosynthesis in methanogenic archaea.
Proc.Natl.Acad.Sci.USA, 111:10520-10525, 2014

PubMed 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, a SepRS⋅SepCysE⋅SepCysS structure model suggests that this ternary complex enables substrate channeling of Sep-tRNA(Cys). A phylogenetic analysis suggests coevolution of SepCysE with SepRS and SepCysS in the last universal common ancestral state. Our findings suggest that the tRNA-dependent Cys biosynthesis proceeds in a multienzyme complex without release of the intermediate and this mechanism may have facilitated the addition of Cys to the genetic code.

PubMed: 25002468
DOI: 10.1073/pnas.1411267111

Experimental method

X-RAY DIFFRACTION (2.803 Å)