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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Remote control of regioselectivity in acyl-acyl carrier protein-desaturases
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Remote control of regioselectivity in acyl-acyl carrier protein-desaturases

机译：远程控制酰基酰基载体蛋白去饱和酶中的区域选择性

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摘要

Regiospecific desaturation of long-chain saturated fatty acids has been described as approaching the limits of the discriminatory power of enzymes because the substrate entirely lacks distinguish ing features close to the site of dehydrogenation. To identify the elusive mechanism underlying regioselectivity, we have deter mined two crystal structures of the archetypal Δ9 desaturase from castor in complex with acyl carrier protein (ACP), which show the bound ACP ideally situated to position C9 and C10 of the acyl chain adjacent to the diiron active site for Δ9 desaturation. Analysis of the structures and modeling of the complex between the highly homologous ivy Δ4 desaturase and ACP, identified a residue lo cated at the entrance to the binding cavity, Asp280 in the castor desaturase (Lys275 in the ivy desaturase), which is strictly con served within A9 and A4 enzymes but differs between them. We hypothesized that interaction between Lys275 and the phos phate of the pantetheine, seen in the ivy model, is key to position ing C4 and C5 adjacent to the diiron center for Δ4 desaturation. Mutating castor Asp280 to Lys resulted in a major shift from Δ9 to Δ4 desaturation. Thus, interaction between desaturase side chain 280 and phospho-serine 38 of ACP, approximately 27 A from the site of double-bond formation, predisposes ACP binding that favors either A9 or A4 desaturation via repulsion (acidic side chain) or attraction (positively charged side chain), respectively. Under standing the mechanism underlying remote control of regioselec tivity provides the foundation for reengineering desaturase enzymes to create designer chemical feedstocks that would pro vide alternatives to those currently obtained from petrochemicals.
机译：长链饱和脂肪酸的区域特异性去饱和已被描述为接近酶的鉴别能力的极限，因为底物完全缺乏接近脱氢位点的区分特征。为了确定区域选择性的难以捉摸的机制，我们从蓖麻中确定了原型Δ9去饱和酶的两个晶体结构，并结合了酰基载体蛋白（ACP），表明结合的ACP理想地位于与相邻的酰基链的C9和C10位置Δ9去饱和的二价铁活性位点。分析高度同源的常春藤Δ4去饱和酶和ACP之间的复合物的结构和模型，确定了残基位于结合腔入口处，即蓖麻去饱和酶中的Asp280（常春藤去饱和酶中的Lys275），这是严格保留的在A9和A4酶中，但两者之间有所不同。我们假设在常春藤模型中可见，Lys275与泛胺磷酸盐之间的相互作用是将C4和C5置于与二价铁的中心相邻进行Δ4去饱和的关键。将蓖麻Asp280突变为Lys导致从Δ9去饱和到Δ4去饱和的主要转变。因此，去饱和酶侧链280和ACP的磷酸丝氨酸38之间的相互作用（距双键形成位点约27 A）预先形成了ACP结合，该结合有利于通过排斥（酸性侧链）或吸引（带正电荷）使A9或A4脱饱和侧链）。长期以来，对区域选择性进行远程控制的机制为重新设计去饱和酶提供了基础，从而创造出了设计者可作为石油化工产品原料的替代品的化学原料。

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  • 作者

    Jodie E. Guy; Edward Whittle; Martin Moche; Johan Lengqvist; Ylva Lindqvist; John Shanklin;

  • 作者单位

    Department of Medical Biochemistry and Biophysics, Molecular Structural Biology, Karolinska Institutet, Tomtebodavagen 6, S-171 77 Stockholm,Sweden;

    Department of Biology, Brookhaven National Laboratory, Upton, NY 11973;

    Department of Medical Biochemistry and Biophysics StructuralGenomics Consortium, Karolinska Institutet, S-171 77 Stockholm, Sweden;

    Department of Medical Biochemistry and Biophysics, Chemistry I,Karolinska Institutet, S-171 77 Stockholm, Sweden;

    Department of Medical Biochemistry and Biophysics, Molecular Structural Biology, Karolinska Institutet, Tomtebodavagen 6, S-171 77 Stockholm,Sweden;

    Department of Biology, Brookhaven National Laboratory, Upton, NY 11973;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    diiron enzyme; enzyme redesign; lipid metabolism; enzyme mechanism;

    机译：二铁酶酶重新设计;脂质代谢酶机制;

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