Modified mevalonate pathway of the archaeon Aeropyrum pernix proceeds via trans-anhydromevalonate 5-phosphate
Modified mevalonate pathway of the archaeon Aeropyrum pernix proceeds via trans-anhydromevalonate 5-phosphate
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DOI：
10.1073/pnas.1809154115
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发表时间：
2018-10-02
影响因子：
11.1
通讯作者：
Hemmi, Hisashi
中科院分区：
文献类型：
--
作者：
Hayakawa, Hajime;Motoyama, Kento;Hemmi, Hisashi
改良的甲羟戊酸途径被认为是一般古细菌中类异戊二烯的上游生物合成途径。通过发现保守酶异戊烯基磷酸激酶，部分鉴定的途径被提出来解释围绕磷酸甲羟戊酸激酶和二磷酸甲羟戊酸脱羧酶缺乏的谜团。磷酸甲羟戊酸脱羧酶被认为是填补5-磷酸甲羟戊酸和磷酸异戊烯酯之间途径中缺失的环节。这种酶是最近从盐古菌和某些 Chroloflexi 细菌中发现的，但它们的酶与二磷酸甲羟戊酸脱羧酶密切同源，而大多数古菌中不存在二磷酸甲羟戊酸脱羧酶。在这项研究中，我们使用比较基因组分析从超嗜热古菌Aeropyrum pernix中找到了两种可以替代磷酸甲羟戊酸脱羧酶的酶。一种被注释为推定乌头酸酶的酶催化甲羟戊酸 5-磷酸脱水，形成以前未知的中间体，反式脱水甲羟戊酸 5-磷酸。然后，属于 UbiD 脱羧酶家族的另一种酶（可能需要类似 UbiX 的伴侣）将中间体转化为磷酸异戊烯基酯。它们的活性通过体外重组酶测定得到证实，并且还在 A. pernix 的无细胞提取物中进行了检测。这些数据将 A. pernix 和可能的大多数古细菌的修饰甲羟戊酸途径与所有已知的甲羟戊酸途径区分开来，例如真核生物型经典途径、盐古菌型修饰途径和最近从嗜酸热原体发现的另一种修饰途径。
The modified mevalonate pathway is believed to be the upstream biosynthetic route for isoprenoids in general archaea. The partially identified pathway has been proposed to explain a mystery surrounding the lack of phosphomevalonate kinase and diphosphomevalonate decarboxylase by the discovery of a conserved enzyme, isopentenyl phosphate kinase. Phosphomevalonate decarboxylase was considered to be the missing link that would fill the vacancy in the pathway between mevalonate 5-phosphate and isopentenyl phosphate. This enzyme was recently discovered from haloarchaea and certain Chroloflexi bacteria, but their enzymes are close homologs of diphosphomevalonate decarboxylase, which are absent in most archaea. In this study, we used comparative genomic analysis to find two enzymes from a hyperthermophilic archaeon, Aeropyrum pernix, that can replace phosphomevalonate decarboxylase. One enzyme, which has been annotated as putative aconitase, catalyzes the dehydration of mevalonate 5-phosphate to form a previously unknown intermediate, trans-anhydromevalonate 5-phosphate. Then, another enzyme belonging to the UbiD-decarboxylase family, which likely requires a UbiX-like partner, converts the intermediate into isopentenyl phosphate. Their activities were confirmed by in vitro assay with recombinant enzymes and were also detected in cell-free extract from A. pernix These data distinguish the modified mevalonate pathway of A. pernix and likely, of the majority of archaea from all known mevalonate pathways, such as the eukaryote-type classical pathway, the haloarchaea-type modified pathway, and another modified pathway recently discovered from Thermoplasma acidophilum.