Cuetos Anibal, Steffen-Munsberg Fabian, Mangas Sanchez Juan, Frese Amina, Bornscheuer Uwe T, Höhne Matthias, Grogan Gideon
York Structural Biology Laboratory, University of York, Heslington, York, YO10 5DD, UK.
Department of Cell and Molecular Biology, Uppsala University, BMC Box 596, 751 24, Uppsala, Sweden.
Chembiochem. 2016 Dec 14;17(24):2308-2311. doi: 10.1002/cbic.201600482. Epub 2016 Oct 31.
Pyridoxal-phosphate (PLP)-dependent enzymes catalyse a remarkable diversity of chemical reactions in nature. A1RDF1 from Arthrobacter aurescens TC1 is a fold type I, PLP-dependent enzyme in the class III transaminase (TA) subgroup. Despite sharing 28 % sequence identity with its closest structural homologues, including β-alanine:pyruvate and γ-aminobutyrate:α-ketoglutarate TAs, A1RDF1 displayed no TA activity. Activity screening revealed that the enzyme possesses phospholyase (E.C. 4.2.3.2) activity towards O-phosphoethanolamine (PEtN), an activity described previously for vertebrate enzymes such as human AGXT2L1, enzymes for which no structure has yet been reported. In order to shed light on the distinctive features of PLP-dependent phospholyases, structures of A1RDF1 in complex with PLP (internal aldimine) and PLP⋅PEtN (external aldimine) were determined, revealing the basis of substrate binding and the structural factors that distinguish the enzyme from class III homologues that display TA activity.
磷酸吡哆醛（PLP）依赖性酶在自然界中催化种类繁多的化学反应。来自金色节杆菌TC1的A1RDF1是III类转氨酶（TA）亚组中的I型折叠PLP依赖性酶。尽管与其最接近的结构同源物（包括β-丙氨酸：丙酮酸和γ-氨基丁酸：α-酮戊二酸TA）具有28%的序列同一性，但A1RDF1没有显示出TA活性。活性筛选表明，该酶对O-磷酸乙醇胺（PEtN）具有磷酸裂解酶（E.C. 4.2.3.2）活性，此前已报道脊椎动物酶如人类AGXT2L1具有这种活性，而这些酶的结构尚未报道。为了阐明PLP依赖性磷酸裂解酶的独特特征，确定了与PLP（内部醛亚胺）和PLP·PEtN（外部醛亚胺）复合的A1RDF1的结构，揭示了底物结合的基础以及将该酶与显示TA活性的III类同源物区分开来的结构因素。
