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Structural Basis for the Catalytic Mechanism of Ethylenediamine- N, N'-disuccinic Acid Lyase, a Carbon-Nitrogen Bond-Forming Enzyme with a Broad Substrate Scope.
Biochemistry ( IF 2.9 ) Pub Date : 2018-05-18 , DOI: 10.1021/acs.biochem.8b00406
Harshwardhan Poddar 1 , Jandré de Villiers 1 , Jielin Zhang 1 , Vinod Puthan Veetil 1 , Hans Raj 1 , Andy-Mark W H Thunnissen 2 , Gerrit J Poelarends 1
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The natural aminocarboxylic acid product ethylenediamine- N, N'-disuccinic acid [( S, S)-EDDS] is able to form a stable complex with metal ions, making it an attractive biodegradable alternative for the synthetic metal chelator ethylenediaminetetraacetic acid (EDTA), which is currently used on a large scale in numerous applications. Previous studies have demonstrated that biodegradation of ( S, S)-EDDS may be initiated by an EDDS lyase, converting ( S, S)-EDDS via the intermediate N-(2-aminoethyl)aspartic acid (AEAA) into ethylenediamine and two molecules of fumarate. However, current knowledge of this enzyme is limited because of the absence of structural data. Here, we describe the identification and characterization of an EDDS lyase from Chelativorans sp. BNC1, which has a broad substrate scope, accepting various mono- and diamines for addition to fumarate. We report crystal structures of the enzyme in an unliganded state and in complex with formate, succinate, fumarate, AEAA, and ( S, S)-EDDS. The structures reveal a tertiary and quaternary fold that is characteristic of the aspartase/fumarase superfamily and support a mechanism that involves general base-catalyzed, sequential two-step deamination of ( S, S)-EDDS. This work broadens our understanding of mechanistic diversity within the aspartase/fumarase superfamily and will aid in the optimization of EDDS lyase for asymmetric synthesis of valuable (metal-chelating) aminocarboxylic acids.

中文翻译:

乙二胺-N,N'-二琥珀酸裂合酶,具有广泛底物范围的碳氮键形成酶的催化机理的结构基础。

天然氨基羧酸产物乙二胺-N,N'-二琥珀酸[(S,S)-EDDS]能够与金属离子形成稳定的络合物,使其成为合成金属螯合剂乙二胺四乙酸(EDTA)的有吸引力的可生物降解的替代品,目前已在许多应用程序中大规模使用。先前的研究表明(S,S)-EDDS的生物降解可能是由EDDS裂解酶引发的,通过中间体N-(2-氨基乙基)天冬氨酸(AEAA)将(S,S)-EDDS转化为乙二胺和两个分子富马酸盐。但是,由于缺乏结构数据,目前对该酶的了解有限。在这里,我们描述了螯虾属EDDS裂解酶的鉴定和表征。BNC1具有广泛的基板范围,除富马酸酯外,还接受各种单胺和二胺。我们报告了酶的晶体结构处于未结合状态,并与甲酸盐,琥珀酸盐,富马酸盐,AEEA和(S,S)-EDDS形成复合物。该结构揭示了天冬氨酸酶/富马酸酶超家族的特征性的三级和四级折叠,并支持了涉及一般的碱催化的,顺序的两步脱氨(EDS)-EDDS的机制。这项工作拓宽了我们对天冬氨酸酶/富马酸酶超家族内机制多样性的理解,并将有助于优化EDDS裂解酶以优化不对称合成有价值的(金属螯合)氨基羧酸。该结构揭示了天冬氨酸酶/富马酸酶超家族的特征性的三级和四级折叠,并支持了涉及一般的碱催化的,顺序的两步脱氨(EDS)-EDDS的机制。这项工作拓宽了我们对天冬氨酸酶/富马酸酶超家族内机制多样性的理解,并将有助于优化EDDS裂解酶以优化不对称合成有价值的(金属螯合)氨基羧酸。该结构揭示了天冬氨酸酶/富马酸酶超家族的特征性的三级和四级折叠,并支持了涉及一般的碱催化的,顺序的两步脱氨(EDS)-EDDS的机制。这项工作拓宽了我们对天冬氨酸酶/富马酸酶超家族内机制多样性的理解,并将有助于优化EDDS裂解酶以优化不对称合成有价值的(金属螯合)氨基羧酸。
更新日期:2018-05-09
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