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首页> 外文期刊>Journal of Molecular Biology >The 2.5 angstrom resolution structure of the JeI42 fab fragment HPr complex
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The 2.5 angstrom resolution structure of the JeI42 fab fragment HPr complex

机译：JeI42晶圆厂HPr复合物的2.5埃分辨率结构

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The tertiary structure of Jel42 Fab fragment complexed with HPr, a phos phocarrier protein of the phosphoenolpyruvate:sugar phosphotransferase system of Escherichia coli, has been determined at 2.5 Angstrom resolution. X-ray diffraction from a larger crystal provided 22,067 unique reflections as compared to 14,763 unique reflections (2.8 Angstrom resolution), which were obtained previously from a smaller crystal. The higher resolution allowed for more precise location of amino acid side-chains and for the location of well-ordered water molecules. Five more residues in the Fab fragment are found to be involved in binding HPr and two additional residues are identified as part of the epitope, bringing the totals to 24 and 16, respectively. At least nine water molecules are found at the interface between the two proteins, and these mediate hydrogen bonding interactions between the Fab fragment and HPr. Three additional hydrogen bonds have been identified (bringing the total to ten) and one salt-bridge occurs between LysL50 of the L2 complementarity-determining region (CDR) and GluP66 of HPr. This salt-bridge is the only interaction between HPr and CDRL2; thus all six CDRs are involved in binding. Inspection and empirical energy minimization of mutant HPrs in the complex indicate that, in some cases in the binding interaction, water molecules may compensate for residue alterations. Binding to the mutant SerP64Tyr HPr may require a movement of the HPr main chain. The active centre region of HPr, which is not involved in binding the antibody, and which was not resolved in the 2.8 Angstrom resolution structure of the complex, was determined. This active centre determined at pH 5.8, which is completely free of intermolecular contacts due to crystal packing, shows a potential hydrogen bond between the AsnP12 OD1 atom and the HisP15 NE2 atom, and no involvement of the C terminus with HisP15. The HisP15 ND1 atom is the site of phosphorylation in HPr. Although a specific amino acid at residue 12 is not conserved in HPr molecules from all species, a hydrogen bond between the side-chains of residue 12 and HisP15 may be a conserved feature of the active centres. (C) 1998 Academic Press. [References: 91]
机译：已经在2.5埃的分辨率下确定了与HPr复合的Jel42 Fab片段的三级结构，HPr是大肠杆菌的磷酸烯醇丙酮酸：糖磷酸转移酶系统的磷酸载体蛋白。与先前从较小晶体获得的14,763个独特反射（2.8埃分辨率）相比，来自较大晶体的X射线衍射提供了22,067个独特反射。较高的分辨率可实现氨基酸侧链的更精确定位以及水分子的有序排列。发现Fab片段中的另外五个残基参与结合HPr，并且鉴定出两个另外的残基作为表位的一部分，使总数分别达到24和16。在两种蛋白质之间的界面上至少发现了九个水分子，它们介导了Fab片段和HPr之间的氢键相互作用。已经确定了三个附加的氢键（将总数增加到十个），并且在L2互补决定区（CDR）的LysL50和HPr的GluP66之间存在一个盐桥。这种盐桥是HPr和CDRL2之间的唯一相互作用;因此所有六个CDR都参与结合。对复合物中突变型HPrs的检查和经验能量最小化表明，在某些情况下，在结合相互作用中，水分子可能补偿残基的变化。结合突变体SerP64Tyr HPr可能需要移动HPr主链。确定了HPr的活性中心区域，该区域不参与抗体结合，并且未在复合物的2.8埃分辨率结构中解析。在pH 5.8处确定的该活性中心由于晶体堆积而完全没有分子间接触，显示出AsnP12 OD1原子和HisP15 NE2原子之间的潜在氢键，而C末端不参与HisP15。 HisP15 ND1原子是HPr中的磷酸化位点。尽管并非所有物种的HPr分子中残基12处的特定氨基酸都是保守的，但残基12和HisP15的侧链之间的氢键可能是活性中心的保守特征。 （C）1998年学术出版社。 [参考：91]

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