Hartmann Rune, Justesen Just, Sarkar Saumendra N, Sen Ganes C, Yee Vivien C
Department of Molecular Cardiology and Center for Structural Biology, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
Mol Cell. 2003 Nov;12(5):1173-85. doi: 10.1016/s1097-2765(03)00433-7.
2'-5'-oligoadenylate synthetases are interferon-induced, double-stranded RNA-activated antiviral enzymes which are the only proteins known to catalyze 2'-specific nucleotidyl transfer. This crystal structure of a 2'-5'-oligoadenylate synthetase reveals a structural conservation with the 3'-specific poly(A) polymerase that, coupled with structure-guided mutagenesis, supports a conserved catalytic mechanism for the 2'- and 3'-specific nucleotidyl transferases. Comparison with structures of other superfamily members indicates that the donor substrates are bound by conserved active site features while the acceptor substrates are oriented by nonconserved regions. The 2'-5'-oligoadenylate synthetases are activated by viral double-stranded RNA in infected cells and initiate a cellular response by synthesizing 2'-5'-oligoadenylates, which in turn activate RNase L. This crystal structure suggests that activation involves a domain-domain shift and identifies a putative dsRNA activation site that is probed by mutagenesis, thus providing structural insight into cellular recognition of viral double-stranded RNA.
2'-5'-寡腺苷酸合成酶是干扰素诱导的、双链RNA激活的抗病毒酶，是已知唯一能催化2'-特异性核苷酸转移的蛋白质。这种2'-5'-寡腺苷酸合成酶的晶体结构揭示了与3'-特异性聚腺苷酸聚合酶的结构保守性，结合结构导向诱变，支持2'-和3'-特异性核苷酸转移酶的保守催化机制。与其他超家族成员结构的比较表明，供体底物由保守的活性位点特征结合，而受体底物由非保守区域定向。2'-5'-寡腺苷酸合成酶在受感染细胞中被病毒双链RNA激活，并通过合成2'-5'-寡腺苷酸引发细胞反应，进而激活RNase L。这种晶体结构表明激活涉及结构域-结构域移位，并确定了一个通过诱变探测的假定双链RNA激活位点，从而为细胞对病毒双链RNA的识别提供了结构上的见解。
