Characterization and evolutionary history of an archaeal kinase involved in selenocysteinyl-tRNA formation.

ABSTRACT: Selenocysteine (Sec)-decoding archaea and eukaryotes employ a unique route of Sec-tRNA(Sec) synthesis in which O-phosphoseryl-tRNA(Sec) kinase (PSTK) phosphorylates Ser-tRNA(Sec) to produce the O-phosphoseryl-tRNA(Sec) (Sep-tRNA(Sec)) substrate that Sep-tRNA:Sec-tRNA synthase (SepSecS) converts to Sec-tRNA(Sec). This study presents a biochemical characterization of Methanocaldococcus jannaschii PSTK, including kinetics of Sep-tRNA(Sec) formation (K(m) for Ser-tRNA(Sec) of 40 nM and ATP of 2.6 mM). PSTK binds both Ser-tRNA(Sec) and tRNA(Sec) with high affinity (K(d) values of 53 nM and 39 nM, respectively). The ATPase activity of PSTK may be activated via an induced fit mechanism in which binding of tRNA(Sec) specifically stimulates hydrolysis. Albeit with lower activity than ATP, PSTK util

SUBMITTER: Sherrer RL 

PROVIDER: S-EPMC2275090 | biostudies-literature | 2008 Mar

REPOSITORIES: biostudies-literature