title: Synthesis of cysteinyl-tRNACys by a prolyl-tRNA synthetase.
abstract: The question of how cysteinyl-tRNA(Cys) is synthesized in organisms that lack a canonical cysteinyl-tRNA synthetase (CysRS) is an important open question in understanding protein synthesis. The prolyl-tRNA synthetase (ProRS) of wide ranging organisms has the ability to mis-activate cysteine without editing. This raises the question of whether the mis-activated cysteine can be charged to tRNA(Cys) to synthesize the correctly matched cys-tRNA(Cys), which may serve as an option in organisms that lack the conventional CysRS. Despite intense searches, such an activity has not been found. Here we show that the ProRS of the radiation-resistant bacterium Deinococcus radiodurans has the ability to charge cysteine to tRNA(Cys) and to retain the cognate pair cys-tRNA(Cys) stably without editing. The cysteinylation by D. radiodurans ProRS is not the major route for synthesis of cys-tRNA(Cys), however, because the organism encodes the conventional CysRS. Nonetheless, the synthesis of cys-tRNA(Cys) in vitro is important and it is unlike previously documented mis-charging of Methanocaldococcus jannaschii ProRS, which synthesizes cys-tRNA(Pro) but not cys-tRNA(Cys). We suggest that the cysteinylation activity of D. radiodruans ProRS may, in the presence of additional factors, offer one option to organisms that lack the conventional CysRS to synthesize cysteinyl-tRNA(Cys) in vivo.
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
authors.forename: Chun-Mei
authors.initials: CM
authors.lastname: Zhang
authors.forename: Ya-Ming
authors.initials: YM
authors.lastname: Hou
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry*; D034301:Deinococcus / Q000378:metabolism; D017353:Gene Deletion; D005816:Genetic Complementation Test; D016681:Genome, Fungal; D007700:Kinetics; D017017:Methanococcus / Q000378:metabolism; D009154:Mutation; D017393:RNA Editing; D012343:RNA, Transfer / Q000737:chemistry; D012350:RNA, Transfer, Cys / Q000737:chemistry*; D013379:Substrate Specificity; D013997:Time Factors
chemical_list: D000596:Amino Acids; D012350:RNA, Transfer, Cys; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases; C100134:prolyl T RNA synthetase; C019975:cysteinyl-tRNA synthetase