Characterization and evolutionary history of an archaeal kinase involved in selenocysteinyl-tRNA formation.
Characterization and evolutionary history of an archaeal kinase involved in selenocysteinyl-tRNA formation.
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DOI：
10.1093/nar/gkm1134
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发表时间：
2008-03
影响因子：
14.9
通讯作者：
Söll D
中科院分区：
文献类型：
--
作者：
Sherrer RL;O'Donoghue P;Söll D
硒代半胱氨酸（Sec）解码古细菌和真核生物采用独特的Sec-tRNASec合成途径，其中O-磷酸丝氨酰-tRNASec激酶（PSTK）磷酸化Ser-tRNASec以产生O-磷酸丝氨酰-tRNASec（Sep-tRNASec）底物，Sep-tRNA：Sec-tRNA合酶（SepSecS）将其转化为Sec-tRNASec。本研究提供了詹氏甲烷球菌PSTK的生物化学表征，包括Sep-tRNASec形成的动力学（Ser-tRNASec的Km为40 nM，ATP为2.6 mM）。PSTK以高亲和力结合Ser-tRNASec和tRNASec（Kd值分别为53 nM和39 nM）。PSTK的ATP酶活性可以通过诱导的适合机制激活，其中tRNASec的结合特异性刺激水解。虽然PSTK的活性低于ATP，但它利用GTP、CTP、UTP和dATP作为磷酸供体。与相关激酶的同源性允许预测ATP酶活性位点，包括磷酸结合环（P-环），步行者B和RxxxR基序。Gly 14，Lys 17，Ser 18，Asp 41，Arg 116和Arg 120突变导致酶活性降低，突出了这些保守基序在体内和体外PSTK催化中的重要性。PSTK在其“DxTN”激酶家族背景下的系统发育分析表明，PSTK与SepSecS精确地共同进化，并表明在疟原虫物种中存在先前未鉴定的PSTK。
Selenocysteine (Sec)-decoding archaea and eukaryotes employ a unique route of Sec-tRNASec synthesis in which O-phosphoseryl-tRNASec kinase (PSTK) phosphorylates Ser-tRNASec to produce the O-phosphoseryl-tRNASec (Sep-tRNASec) substrate that Sep-tRNA:Sec-tRNA synthase (SepSecS) converts to Sec-tRNASec. This study presents a biochemical characterization of Methanocaldococcus jannaschii PSTK, including kinetics of Sep-tRNASec formation (Km for Ser-tRNASec of 40 nM and ATP of 2.6 mM). PSTK binds both Ser-tRNASec and tRNASec with high affinity (Kd 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 tRNASec specifically stimulates hydrolysis. Albeit with lower activity than ATP, PSTK utilizes GTP, CTP, UTP and dATP as phosphate-donors. Homology with related kinases allowed prediction of the ATPase active site, comprised of phosphate-binding loop (P-loop), Walker B and RxxxR motifs. Gly14, Lys17, Ser18, Asp41, Arg116 and Arg120 mutations resulted in enzymes with decreased activity highlighting the importance of these conserved motifs in PSTK catalysis both in vivo and in vitro. Phylogenetic analysis of PSTK in the context of its ‘DxTN’ kinase family shows that PSTK co-evolved precisely with SepSecS and indicates the presence of a previously unidentified PSTK in Plasmodium species.
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影响因子：
3.4
作者：
De la Cruz, EM;Sweeney, HL;Ostap, EM
通讯作者：
Ostap, EM
DOI：
10.1073/pnas.67.2.688
发表时间：
1970-01-01
影响因子：
11.1
作者：
MAENPAA, PH;BERNFIELD, MR
通讯作者：
BERNFIELD, MR
影响因子：
2.6
作者：
BUTLER, AR;PORTER, M;STARK, MJR
通讯作者：
STARK, MJR
影响因子：
14.9
作者：
Bahl, A;Brunk, B;Whetzel, P
通讯作者：
Whetzel, P
DOI：
10.1073/pnas.050564797
发表时间：
2000-03-28
影响因子：
11.1
作者：
Graham, DE;Overbeek, R;Woese, CR
通讯作者：
Woese, CR