Finerty P J, Bass B L
Department of Biochemistry and Howard Hughes Medical Institute, 6110a EIHG, Salt Lake City, UT, 84112, USA.
J Mol Biol. 1997 Aug 15;271(2):195-208. doi: 10.1006/jmbi.1997.1177.
Proteins containing C2H2 type zinc finger motifs represent one of the largest classes of nucleic acid-binding proteins found in nature. We describe a novel zinc finger protein, dsRBP-ZFa, isolated by screening an expression library with dsRNA. The dsRBP-ZFa cDNA encodes a protein containing seven zinc finger motifs and an acidic C-terminal domain. Mobility shift experiments demonstrate that dsRBP-ZFa binds dsRNA and RNA-DNA hybrids with nanomolar dissociation constants and in a sequence independent manner. We also show that DNA and single stranded RNA fail to compete with dsRNA for binding suggesting dsRBP-ZFa prefers to bind an A-form helix. Using western analyses we have localized dsRBP-ZFa primarily to the nucleus of Xenopus laevis oocytes. The identification of dsRBP-ZFa provides the first example of a zinc finger protein that is specific for dsRNA. In addition, dsRBP-ZFa does not contain the previously described dsRNA binding motif, suggesting certain zinc fingers may provide an alternative way to recognize the A-form helix.
含有C2H2型锌指基序的蛋白质是自然界中发现的最大一类核酸结合蛋白之一。我们描述了一种新型锌指蛋白dsRBP-ZFa，它是通过用双链RNA筛选表达文库分离得到的。dsRBP-ZFa cDNA编码一种含有七个锌指基序和一个酸性C末端结构域的蛋白质。迁移率变动实验表明，dsRBP-ZFa以纳摩尔解离常数并以序列无关的方式结合双链RNA和RNA-DNA杂交体。我们还表明，DNA和单链RNA不能与双链RNA竞争结合，这表明dsRBP-ZFa更喜欢结合A-型螺旋。通过蛋白质免疫印迹分析，我们已将dsRBP-ZFa主要定位在非洲爪蟾卵母细胞的细胞核中。dsRBP-ZFa的鉴定提供了第一个对双链RNA具有特异性的锌指蛋白实例。此外，dsRBP-ZFa不包含先前描述的双链RNA结合基序，这表明某些锌指可能提供了识别A-型螺旋的另一种方式。
