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.

中文翻译：

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来自嗜热栖热菌的黄素依赖性胸苷酸合酶Thy1的晶体结构，具有额外的C末端结构域。

胸苷酸合酶ThyA和Thy1是催化2'-脱氧尿苷单磷酸形成胸苷单磷酸的酶。Thy1（或ThyX）需要黄素来进行催化反应，而ThyA则不需要。在本研究中，测定了嗜热栖热菌HB8的黄素依赖性胸苷酸合酶Thy1（Tt Thy1，TTHA1096）的晶体结构，其与FAD和磷酸盐的络合度为2.5Å。Tt Thy1是一个与其他Thy1蛋白类似的四聚体分子，与四个FAD分子结合。在Tt Thy1的晶体中，两个磷酸根离子与每个dUMP结合位点结合。Tt的特征Thy1是一个额外的C末端结构域（CTD），它由三个α螺旋和一个β链组成。CTD的功能尚不清楚，数据库分析表明该CTD仅由Deinococcus–Thermus phylum的一部分共享。