In most organisms, Cys-tRNACys is directly synthesized by cysteinyl-tRNA synthetase (CysRS). Many methanogenic archaea, however, use a two-step, indirect pathway to synthesize Cys-tRNACys owing to a lack of CysRS and cysteine-biosynthesis systems. This reaction is catalyzed by O-phosphoseryl-tRNA synthetase (SepRS), Sep-tRNA:Cys-tRNA synthase (SepCysS) and SepRS/SepCysS pathway enhancer (SepCysE) as the transsulfursome, in which SepCysE connects both SepRS and SepCysS. On the transsulfursome, SepRS first ligates an O-phosphoserine to tRNACys, and the mischarged intermediate Sep-tRNACys is then transferred to SepCysS, where it is further modified to Cys-tRNACys. In this study, a subcomplex of the transsulfursome with tRNACys (SepCysS-SepCysE-tRNACys), which is involved in the second reaction step of the indirect pathway, was constructed and then crystallized. The crystals diffracted X-rays to a resolution of 2.6 Å and belonged to space group P6522, with unit-cell parameters a = b = 107.2, c = 551.1 Å. The structure determined by molecular replacement showed that the complex consists of a SepCysS dimer, a SepCysE dimer and one tRNACys in the asymmetric unit.
|Number of pages||4|
|Journal||Acta Crystallographica Section:F Structural Biology Communications|
|Publication status||Published - 2016|
ASJC Scopus subject areas
- Structural Biology
- Condensed Matter Physics