Brown D, Gold L
Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder 80309, USA.
Proc Natl Acad Sci U S A. 1996 Oct 15;93(21):11558-62. doi: 10.1073/pnas.93.21.11558.
Two classes of RNA ligands that bound to separate, high affinity nucleic acid binding sites on Q beta replicase were previously identified. RNA ligands to the two sites, referred to as site I and site II, were used to investigate the molecular mechanism of RNA replication employed by the four-subunit replicase. Replication inhibition by site I- and site II-specific ligands defined two subsets of replicatable RNAs. When provided with appropriate 3' ends, ligands to either site served as replication templates. UV crosslinking experiments revealed that site I is associated with the S1 subunit, site II with elongation factor Tu, and polymerization with the viral subunit of the holoenzyme. These results provide the framework for a three site model describing template recognition and product strand initiation by Q beta replicase.
先前已鉴定出两类与Qβ复制酶上不同的高亲和力核酸结合位点结合的RNA配体。用于这两个位点（分别称为位点I和位点II）的RNA配体被用于研究四亚基复制酶所采用的RNA复制分子机制。位点I和位点II特异性配体对复制的抑制作用定义了可复制RNA的两个亚组。当提供合适的3'末端时，任一位点的配体均可作为复制模板。紫外线交联实验表明，位点I与S1亚基相关联，位点II与延伸因子Tu相关联，而聚合作用则与全酶的病毒亚基相关联。这些结果为描述Qβ复制酶模板识别和产物链起始的三位点模型提供了框架。
