Rajagopal Vaishnavi, Patel Smita S
Department of Biochemistry, UMDNJ, Robert Wood Johnson Medical School, 675 Hoes Lane, Piscataway, NJ 08854, USA.
J Mol Biol. 2008 Feb 8;376(1):69-79. doi: 10.1016/j.jmb.2007.10.070. Epub 2007 Nov 1.
The nonstructural NS3 protein of the hepatitis C virus is a multifunctional enzyme with an N-terminal serine protease activity and a C-terminal helicase activity. The helicase is capable of unwinding both DNA and RNA duplexes; however, the overall processivity of the helicase is fairly low. We show here that single-strand binding (SSB) proteins enhance the unwinding processivity of both the NS3 helicase domain (NS3h) and the full-length protease-helicase NS3-4A. The detailed study of the effect of SSB on the DNA unwinding activity of NS3h indicates that the SSB stabilizes the helicase at the unwinding junction and prevents its dissociation. These results suggest a potential role for either cellular or virus-encoded SSB protein in improving the processivity of the NS3 in vivo.
丙型肝炎病毒的非结构NS3蛋白是一种多功能酶，具有N端丝氨酸蛋白酶活性和C端解旋酶活性。该解旋酶能够解开DNA和RNA双链；然而，解旋酶的整体持续合成能力相当低。我们在此表明，单链结合（SSB）蛋白可增强NS3解旋酶结构域（NS3h）和全长蛋白酶-解旋酶NS3-4A的解旋持续合成能力。对SSB对NS3h的DNA解旋活性影响的详细研究表明，SSB在解旋连接处稳定解旋酶并防止其解离。这些结果提示细胞或病毒编码的SSB蛋白在体内提高NS3的持续合成能力方面可能发挥作用。
