Jedrzejczak Robert, Wang Jiawei, Dauter Miroslawa, Szczesny Roman J, Stepien Piotr P, Dauter Zbigniew
Synchrotron Radiation Research Section, National Cancer Institute, Argonne National Laboratory, Argonne, IL 60439, USA.
Acta Crystallogr D Biol Crystallogr. 2011 Nov;67(Pt 11):988-96. doi: 10.1107/S0907444911040248. Epub 2011 Oct 19.
Suv3 is a helicase that is involved in efficient turnover and surveillance of RNA in eukaryotes. In vitro studies show that human Suv3 (hSuv3) in complex with human polynucleotide phosphorylase has RNA degradosome activity. The enzyme is mainly localized in mitochondria, but small fractions are found in cell nuclei. Here, two X-ray crystallographic structures of human Suv3 in complex with AMPPNP, a nonhydrolysable analog of ATP, and with a short five-nucleotide strand of RNA are presented at resolutions of 2.08 and 2.9 Å, respectively. The structure of the enzyme is very similar in the two complexes and consists of four domains. Two RecA-like domains form the tandem typical of all helicases from the SF2 superfamily which together with the C-terminal all-helical domain makes a ring structure through which the nucleotide strand threads. The mostly helical N-terminal domain is positioned externally with respect to the core of the enzyme. Most of the typical helicase motifs are present in hSuv3, but the protein shows certain unique characteristics, suggesting that Suv3 enzymes may constitute a separate subfamily of helicases.
Suv3是一种解旋酶，参与真核生物中RNA的高效周转和监测。体外研究表明，与人类多核苷酸磷酸化酶形成复合物的人类Suv3（hSuv3）具有RNA降解体活性。该酶主要定位于线粒体，但在细胞核中也发现有少量存在。在此，分别以2.08 Å和2.9 Å的分辨率展示了与ATP的非水解类似物AMPPNP以及与一条短的五核苷酸RNA链形成复合物的人类Suv3的两种X射线晶体结构。两种复合物中该酶的结构非常相似，由四个结构域组成。两个类RecA结构域形成了SF2超家族所有解旋酶典型的串联结构，其与C端全螺旋结构域共同构成一个环状结构，核苷酸链从中穿过。大部分为螺旋结构的N端结构域相对于酶的核心位于外部。hSuv3中存在大多数典型的解旋酶基序，但该蛋白显示出某些独特特征，表明Suv3酶可能构成解旋酶的一个独立亚家族。
