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首页> 外文期刊>Acta crystallographica. Section D, Structural biology >Structure-function study of AKR4C14, an aldo-keto reductase from Thai jasmine rice (Oryza sativa L. ssp. indica cv. KDML105)
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Structure-function study of AKR4C14, an aldo-keto reductase from Thai jasmine rice (Oryza sativa L. ssp. indica cv. KDML105)

机译：aldo-keto AKR4C14结构的研究从泰国香米还原酶(L栽培稻。ssp。

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摘要

Aldo-keto reductases (AKRs) are NADPH/NADP+-dependent oxidoreductase enzymes that metabolize an aldehyde/ketone to the corresponding alcohol. AKR4C14 from rice exhibits a much higher efficiency in metabolizing malondialdehyde (MDA) than do the Arabidopsis enzymes AKR4C8 and AKR4C9, despite sharing greater than 60% amino-acid sequence identity. This study confirms the role of rice AKR4C14 in the detoxification of methylglyoxal and MDA, and demonstrates that the endogenous contents of both aldehydes in transgenic Arabidopsis ectopically expressing AKR4C14 are significantly lower than their levels in the wild type. The apo structure of indica rice AKR4C14 was also determined in the absence of the cofactor, revealing the stabilized open conformation. This is the first crystal structure in AKR subfamily 4C from rice to be observed in the apo form (without bound NADP+). The refined AKR4C14 structure reveals a stabilized open conformation of loop B, suggesting the initial phase prior to cofactor binding. Based on the X-ray crystal structure, the substrate- and cofactor-binding pockets of AKR4C14 are formed by loops A, B, C and β1α1. Moreover, the residues Ser211 and Asn220 on loop B are proposed as the hinge residues that are responsible for conformational alteration while the cofactor binds. The open conformation of loop B is proposed to involve Phe216 pointing out from the cofactor-binding site and the opening of the safety belt. Structural comparison with other AKRs in subfamily 4C emphasizes the role of the substrate-channel wall, consisting of Trp24, Trpll5, Tyr206, Phe216, Leu291 and Phe295, in substrate discrimination. In particular, Leu291 could contribute greatly to substrate selectivity, explaining the preference of AKR4C14 for its straight-chain aldehyde substrate.
机译：Aldo-keto还原酶(AKRs)NADPH /辅酶ii +端依赖氧化还原酶的酶一个醛/酮代谢相应的醇。代谢的效率要高得多丙二醛(MDA)相比拟南芥酶AKR4C8 AKR4C9,尽管分享超过60%的氨基酸序列的身份。本研究证实了水稻AKR4C14的角色甲基乙二醛的解毒和MDA表明,内生的内容转基因拟南芥ectopically中的醛类物质表达AKR4C14明显低于野生型的水平。籼稻AKR4C14也是确定的缺席的辅因子,揭示了稳定开放的构象。从水稻结构AKR亚科4 c在人群的形式(没有绑定辅酶ii +)。揭示了一个精制AKR4C14结构B稳定开放构型的循环,代数余子式之前建议的初始阶段绑定。衬底和cofactor-binding口袋AKR4C14是由循环形成的A, B, C和β1α1。此外,残留Ser211和Asn220循环提出了B的铰链残留负责构象的改变代数余子式绑定。B提出涉及Phe216指出cofactor-binding站点的开放安全带。在亚科4 c AKRs强调的作用Trp24 substrate-channel墙,组成,Trpll5、Tyr206 Phe216 Leu291 Phe295,衬底的歧视。底物作出巨大贡献选择性,解释AKR4C14的偏好直链醛衬底。

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