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首页> 外文期刊>Biochemistry >Structural Basis of Sequential Allosteric Transitions in Tetrameric D-Lactate Dehydrogenases from Three Gram-Negative Bacteria
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Structural Basis of Sequential Allosteric Transitions in Tetrameric D-Lactate Dehydrogenases from Three Gram-Negative Bacteria

机译：三克阴性细菌四聚乳酸脱氢酶中序贯变构转变的结构基础

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摘要

D-Lactate dehydrogenases (D-LDHs) from Fusobacterium nucleatum (FnLDH) and Escherichia coli (EcLDH) exhibit positive cooperativity in substrate binding, and the Pseudomonas aeruginosa enzyme (PaLDH) shows negatively cooperative substrate binding. The apo and ternary complex structures of FnLDH and PaLDH have been determined together with the apo-EcLDH structure. The three enzymes consistently form homotetrameric structures with three symmetric axes, the P-, Q-, and R-axes, unlike Lactobacillus D-LDHs, P-axis-related dimeric enzymes, although apo-FnLDH and EcLDH form asymmetric and distorted quaternary structures. The tetrameric structure allows apo-FnLDH and EcLDH to form wide intersubunit contact surfaces between the opened catalytic domains of the two Q-axis-related subunits in coordination with their asymmetric and distorted quaternary structures. These contact surfaces comprise intersubunit hydrogen bonds and hydrophobic interactions and likely prevent the domain closure motion during initial substrate binding. In contrast, apo-PaLDH possesses a highly symmetrical quaternary structure and partially closed catalytic domains that are favorable for initial substrate binding and forms virtually no intersubunit contact surface between the catalytic domains, which present their negatively charged surfaces to each other at the subunit interface. Complex FnLDH and PaLDH possess highly symmetrical quaternary structures with closed forms of the catalytic domains, which are separate from each other at the subunit interface. Structure-based mutations successfully converted the three enzymes to their dimeric forms, which exhibited no significant cooperativity in substrate binding. These observations indicate that the three enzymes undergo typical sequential allosteric transitions to exhibit their distinctive allosteric functions through the tetrameric structures.
机译：来自Fusobacterum（FNLDH）和大肠杆菌（ECLICH）的D-乳酸脱氢酶（D-LDHS）表现出底物结合的阳性合作，并且假单胞菌铜绿素（PALDH）显示出负合作基底结合。 FNLDH和PALDH的APO和三元复杂结构与APO-ECLDH结构一起确定。三种酶始终形成具有三个对称轴，P轴，Q-和R轴的同型异构体结构，与乳酸杆菌D-LDH，P轴相关的二聚体酶不同，尽管APO-FNLDH和ECLDH形成不对称和扭曲的第四纪结构。四聚结构允许Apo-FnldH和EcldH在两个Q轴相关亚基的打开的催化结构域之间形成宽的IntersubUnit接触表面，其与其不对称和扭曲的季结构配位。这些接触表面包括intersubunit氢键和疏水性相互作用，并且可能在初始衬底结合期间防止畴闭合运动。相反，APO-PALDH具有高度对称的四元结构和部分闭合的催化结构域，其有利于初始衬底结合，并且在催化结构域之间形成几乎没有缺口的接触表面，其在亚基界面处彼此呈现它们带负电的表面。复杂的FNLDH和PALDH具有高度对称的四元结构，具有闭合形式的催化结构域，其在亚基界面处彼此分开。基于结构的突变成功地将三种酶转化为其二聚体形式，其在底物结合中表现出显着的合作性。这些观察结果表明，三种酶经历典型的序贯颠跃转变，以通过四聚体结构表现出其独特的颠振功能。

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  • 来源
    《Biochemistry》 |2018年第37期|共19页
  • 作者

    Furukawa Nayuta; Miyanaga Akimasa; Nakajima Masahiro; Taguchi Hayao;

  • 作者单位

    Tokyo Univ Sci Fac Sci &

    Technol Dept Appl Biol Sci 2641 Yamazaki Noda Chiba 2788510 Japan;

    Tokyo Inst Technol Dept Chem Meguro Ku 2-12-1 O Okayama Tokyo 1528551 Japan;

    Tokyo Univ Sci Fac Sci &

    Technol Dept Appl Biol Sci 2641 Yamazaki Noda Chiba 2788510 Japan;

    Tokyo Univ Sci Fac Sci &

    Technol Dept Appl Biol Sci 2641 Yamazaki Noda Chiba 2788510 Japan;

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  • 正文语种 eng
  • 中图分类 生物化学;
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