7,8-Dihydro-d-neopterin 2′,3′-cyclic phosphate (H₂N-cP) is the first intermediate in biosynthesis of the pterin portion of tetrahydromethanopterin (H₄MPT), a C₁ carrier coenzyme first identified in the methanogenic archaea. This intermediate is produced from GTP by MptA (MJ0775 gene product), a new class of GTP cyclohydrolase I [Grochowski, L. L., Xu, H., Leung, K., and White, R. H. (2007) Biochemistry 46, 6658−6667]. Here we report the identification of a cyclic phosphodiesterase that hydrolyzes the cyclic phosphate of H₂N-cP and converts it to a mixture of 7,8-dihydro-d-neopterin 2′-monophosphate and 7,8-dihydro-d-neopterin 3′-monophosphate. The enzyme from Methanocaldococcus jannachii is designated MptB (MJ0837 gene product) to indicate that it catalyzes the second step of the biosynthesis of methanopterin. MptB is a member of the HD domain superfamily of enzymes, which require divalent metals for activity. Direct metal analysis of the recombinant enzyme demonstrated that MptB contained 1.0 mol of zinc and 0.8 mol of iron per protomer. MptB requires Fe²⁺ for activity, the same as observed for MptA. Thus the first two enzymes involved in H₄MPT biosynthesis in the archaea are Fe²⁺ dependent.

中文翻译：

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Fe ²⁺依赖的环状磷酸二酯酶催化7,8-二氢-d-新蝶呤2'，3'-环状磷酸盐在甲烷蝶呤生物合成中的水解

7,8-二氢- d -neopterin 2'，3'-环磷酸（H ₂ N-二厘泊）是在tetrahydromethanopterin的蝶呤部分（H的生物合成中的第一中间₄ MPT），一个C ₁载体辅酶第一中鉴定产甲烷的古细菌。该中间体是由MTPA（MJ0775基因产物）从GTP产生的，MptA是新型的GTP环水解酶I [Grochowski，LL，Xu，H.，Leung，K.，and White，RH（2007）Biochemistry 46，6658−6667] 。这里，我们报告水解H的环状磷酸酯的环状磷酸二酯酶的识别₂的N-厘泊，将其转化为7,8-二氢-的混合物d -neopterin 2'-单磷酸和7,8-二氢- d-新蝶呤3'-单磷酸酯。来自詹氏甲烷球菌的酶被命名为MptB（MJ0837基因产物），表明它催化甲烷蝶呤生物合成的第二步。MptB是酶的HD结构域超家族的成员，该酶需要二价金属才能发挥活性。对重组酶的直接金属分析表明，每个原核生物中MptB含有1.0摩尔的锌和0.8摩尔的铁。MptB的活性需要Fe ²⁺，与MptA相同。因此，古细菌中参与H ₄ MPT生物合成的前两种酶是Fe ²⁺依赖性的。