Sulfolobus shibatae CCA-adding enzyme forms a tetramer upon binding two tRNA molecules: A scrunching-shuttling model of CCA specificity.
Sulfolobus shibatae CCA-adding enzyme forms a tetramer upon binding two tRNA molecules: A scrunching-shuttling model of CCA specificity.
复制标题
Sulfolobus shibatae CCA 添加酶在结合两个 tRNA 分子后形成四聚体：CCA 特异性的挤压-穿梭模型。
DOI：
10.1006/jmbi.2000.4189
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
Steitz,TA
中科院分区：
文献类型：
--
作者：
Li,F;Wang,J;Steitz,TA
tRNA CCA添加酶将CCA逐步添加到未模板化的未成熟转移RNA分子，但具有高特异性。我们研究了低聚状态的酶从Sulfolobus柴田和它的结合转移RNA分子，使用各种生物物理和生物化学方法，包括尺寸排阻色谱，多角度激光光散射，小角度X射线散射，凝胶电泳带迁移率变动分析。48kDa单体在溶液中形成稳定的耐盐二聚体。通过两个tRNA分子的结合诱导二聚体酶进一步二聚化以形成四聚体。只有两个结合的tRNA分子的四聚体的形成使我们认为，一对活性位点可能是专门添加两个C碱基，这导致在引物链的scrunching。相邻的第二对活性位点可以特异于在添加两个C碱基之后添加A，这使得3′末端足够长以到达第二对活性位点。
The tRNA CCA-adding enzyme adds CCA stepwise to immature transfer RNA molecules untemplated, but with high specificity. We examined the oligomerization state of the enzyme from Sulfolobus shibatae and its binding to transfer RNA molecules, using various biophysical and biochemical methods including size exclusion chromatography, multi-angle laser light scattering, small-angle X-ray scattering, and gel electrophoresis band mobility shift assay. The 48 kDa monomer forms a stable salt- resistant dimer in solution. Further dimerization of the dimeric enzyme to form a tetramer is induced by the binding of two tRNA molecules. The formation of a tetramer with only two bound tRNA molecules leads us to suggest that one pair of active sites may be specific for adding two C bases, which results in scrunching of the primer strand. An adjacent second pair of active sites may be specific for adding A after addition of two C bases which makes the 3′ terminus long enough to reach the second pair of active sites.