Degradation pathway of the phosphonate ciliatine: Crystal structure of 2-aminoethylphosphonate transaminase
Degradation pathway of the phosphonate ciliatine: Crystal structure of 2-aminoethylphosphonate transaminase
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DOI：
10.1021/bi026231v
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发表时间：
2002-11-05
期刊：
影响因子：
2.9
通讯作者：
Herzberg, O
中科院分区：
文献类型：
--
作者：
Chen, CCH;Zhang, H;Herzberg, O
膦酸盐允许某些生物体在其他恶劣的环境中茁壮成长，2-氨基乙基膦酸盐（AEP）是许多细胞膦酸盐的前体。AEP转氨酶（AEPT）是膦酸盐合成和降解途径中必需的酶。用66个硒原子的多波长异常衍射测定了AEP转氨酶的晶体结构。在2.2埃分辨率下，精细化的结构显示出与I型氨基转移酶的二聚体双结构域结构相似的整体褶皱和活性位点位置。活性位点包含一个辅助因子，吡哆醛5'-磷酸（PLP）和产物磷酸乙醛。与其他I型转氨酶结构的比较表明，plp -蛋白相互作用是保守的。结合底物和产物的模型揭示了AEP识别的结构基础和cc-碳上质子消除的立体特异性，并表明了反应路径上的构象变化。
Phosphonates allow certain organisms to thrive in otherwise hostile environments, and 2-aminoethylphosphonate (AEP) is a precursor of many cellular phosphonates. AEP transaminase (AEPT) is an enzyme essential to phosphonate synthesis and degradation pathways. The crystal structure of AEP transaminase was determined by multiwavelength anomalous diffraction of 66 selenium atoms. The refined structure at 2.2 Angstrom resolution revealed an overall fold and active site location similar to those of the dimeric, two-domain structure of type I aminotransferases. The active site contains a cofactor, pyridoxal 5'-phosphate (PLP), and the product phosphonoacetaldehyde. Comparison with other type I aminotransferase structures shows that the PLP-protein interactions are conserved. Modeling of bound substrates and products reveals the structural basis for AEP recognition and the stereospecificity of proton elimination at the cc-carbon and indicates conformational changes along the reaction pathway.