Ogawa Aoba, Sampei Gen Ichi, Kawai Gota
Department of Life and Environmental Sciences, Faculty of Engineering, Chiba Institute of Technology, Narashino, Chiba 275-0016, Japan.
Department of Engineering Science, Graduate School of Informatics and Engineering, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan.
Acta Crystallogr F Struct Biol Commun. 2019 Jun 1;75(Pt 6):450-454. doi: 10.1107/S2053230X19007192. Epub 2019 Jun 6.
The thymidylate synthases ThyA and Thy1 are enzymes that catalyse the formation of thymidine monophosphate from 2'-deoxyuridine monophosphate. Thy1 (or ThyX) requires flavin for catalytic reactions, while ThyA does not. In the present study, the crystal structure of the flavin-dependent thymidylate synthase Thy1 from Thermus thermophilus HB8 (TtThy1, TTHA1096) was determined in complex with FAD and phosphate at 2.5 Å resolution. TtThy1 is a tetrameric molecule like other Thy1 proteins, to which four FAD molecules are bound. In the crystal of TtThy1, two phosphate ions were bound to each dUMP-binding site. The characteristic feature of TtThy1 is the existence of an extra C-terminal domain (CTD) consisting of three α-helices and a β-strand. The function of the CTD is unknown and database analysis showed that this CTD is only shared by part of the Deinococcus-Thermus phylum.
胸苷酸合成酶ThyA和Thy1是催化由2'-脱氧尿苷单磷酸形成胸苷单磷酸的酶。Thy1（或ThyX）催化反应需要黄素，而ThyA则不需要。在本研究中，测定了嗜热栖热菌HB8（TtThy1，TTHA1096）中黄素依赖性胸苷酸合成酶Thy1与FAD和磷酸盐复合物的晶体结构，分辨率为2.5Å。TtThy1与其他Thy1蛋白一样是四聚体分子，结合有四个FAD分子。在TtThy1晶体中，每个dUMP结合位点结合有两个磷酸根离子。TtThy1的特征是存在一个由三个α螺旋和一条β链组成的额外的C末端结构域（CTD）。CTD的功能尚不清楚，数据库分析表明，只有部分嗜热栖热菌门细菌具有这种CTD。
