Homology modeling of the three membrane proteins of the dhurrin metabolon: Catalytic sites, membrane surface association and protein-protein interactions
Homology modeling of the three membrane proteins of the dhurrin metabolon: Catalytic sites, membrane surface association and protein-protein interactions
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DOI：
10.1016/j.phytochem.2011.05.001
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发表时间：
2011-12-01
期刊：
影响因子：
3.8
通讯作者：
Moller, Birger Lindberg
中科院分区：
文献类型：
--
作者：
Jensen, Kenneth;Osmani, Sarah Anne;Moller, Birger Lindberg
代谢子（大分子酶复合物）的形成促进了生物合成途径中底物的通道。代谢物形成是一个动态过程，其中形成由弱蛋白质-蛋白质相互作用介导的瞬时结构。在山梨醇中，生氰葡糖苷dhurrin在涉及两种细胞色素P450（CYP）CYP 79 A1和CYP 71 E1、葡糖基转移酶（UGT 85 B1）和氧化还原配偶体NADPH依赖性细胞色素P450还原酶（CPR）的途径中衍生自L-酪氨酸。实验证据表明，该途径的酶形成代谢子。使用Syphony软件和可用的相关晶体结构进行三种膜结合蛋白的同源性建模。确定了参与底物和中间体在CYP 79 A1和CYP 71 E1活性位点紧密定位的残基。在两种CYP中，靠近N-末端跨膜锚和F'和G螺旋之间的疏水表面结构域被鉴定为参与膜锚定。两个CYP的近端表面显示带正电荷的补丁互补于携带FMN结构域的CPR上带负电荷的凸起。在CYP 71 E1中鉴定了位于膜锚相对面上的一片表面暴露的带正电荷的氨基酸残基，可能通过该蛋白质中的高变带负电荷环参与结合UGT 85 B1。(C)2011爱思唯尔有限公司版权所有。
Formation of metabolons (macromolecular enzyme complexes) facilitates the channelling of substrates in biosynthetic pathways. Metabolon formation is a dynamic process in which transient structures mediated by weak protein-protein interactions are formed. In Sorghum, the cyanogenic glucoside dhurrin is derived from L-tyrosine in a pathway involving the two cytochromes P450 (CYPs) CYP79A1 and CYP71E1, a glucosyltransferase (UGT85B1), and the redox partner NADPH-dependent cytochrome P450 reductase (CPR). Experimental evidence suggests that the enzymes of this pathway form a metabolon. Homology modeling of the three membrane bound proteins was carried out using the Sybyl software and available relevant crystal structures. Residues involved in tight positioning of the substrates and intermediates in the active sites of CYP79A1 and CYP71E1 were identified. In both CYPs, hydrophobic surface domains close to the N-terminal trans-membrane anchor and between the F' and G helices were identified as involved in membrane anchoring. The proximal surface of both CYPs showed positively charged patches complementary to a negatively charged bulge on CPR carrying the FMN domain. A patch of surface exposed, positively charged amino acid residues positioned on the opposite face of the membrane anchor was identified in CYP71E1 and might be involved in binding UGT85B1 via a hypervariable negatively charged loop in this protein. (C) 2011 Elsevier Ltd. All rights reserved.