Sousa R, Rose J, Wang B C
Department of Biochemistry, University of Texas Health Science Center, San Antonio 78284-7862.
J Mol Biol. 1994 Nov 18;244(1):6-12. doi: 10.1006/jmbi.1994.1699.
We have solved the structure of a chimeric T7/T3 RNA polymerase (RNAP) in an orthorhombic crystal by molecular replacement with the T7 RNAP structure determined from a monoclinic crystal. The structure of the protruding "thumb" subdomain of the polymerase appears very different in these two crystals apparently because of differences in packing contacts made by the thumb subdomain. These observations support the proposal that the thumb subdomain is flexible and can wrap around bound template to obstruct polymerase: template dissociation during processive synthesis.
我们通过分子置换法，利用从单斜晶体中确定的T7 RNA聚合酶（RNAP）结构，解析了正交晶体中嵌合T7/T3 RNA聚合酶（RNAP）的结构。在这两种晶体中，聚合酶突出的“拇指”亚结构域的结构看起来非常不同，这显然是由于拇指亚结构域形成的堆积接触存在差异。这些观察结果支持了这样一种观点，即拇指亚结构域是灵活的，能够围绕结合的模板缠绕，从而在连续合成过程中阻碍聚合酶与模板的解离。
