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首页> 外文期刊>Biochemistry >Crystal Structures of Cystathionine β-Synthase from Saccharomyces cerevisiae: One Enzymatic Step at a Time
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Crystal Structures of Cystathionine β-Synthase from Saccharomyces cerevisiae: One Enzymatic Step at a Time

机译：来自酿酒酵母的胱硫胺β-合酶的晶体结构：一次一个酶促步骤

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Cystathionine β-synthase (CBS) is a key regulator of sulfur amino acid metabolism, taking homocysteine from the methionine cycle to the biosynthesis of cysteine via the trans-sulfuration pathway. CBS is also a predominant source of H_(2)S biogenesis. Roles for CBS have been reported for neuronal death pursuant to cerebral ischemia, promoting ovarian tumor growth, and maintaining drug-resistant phenotype by controlling redox behavior and regulating mitochondrial bioenergetics. The trans-sulfuration pathway is well-conserved in eukaryotes, but the analogous enzymes have different enzymatic behavior in different organisms. CBSs from the higher organisms contain a heme in an N-terminal domain. Though the presence of the heme, whose functions in CBSs have yet to be elucidated, is biochemically interesting, it hampers UV–vis absorption spectroscopy investigations of pyridoxal 5′-phosphate (PLP) species. CBS from Saccharomyces cerevisiae (yCBS) naturally lacks the heme-containing N-terminal domain, which makes it an ideal model for spectroscopic studies of the enzymological reaction catalyzed and allows structural studies of the basic yCBS catalytic core (yCBS-cc). Here we present the crystal structure of yCBS-cc, solved to 1.5 ?. Crystal structures of yCBS-cc in complex with enzymatic reaction intermediates have been captured, providing a structural basis for residues involved in catalysis. Finally, the structure of the yCBS-cc cofactor complex generated by incubation with an inhibitor shows apparent off-pathway chemistry not normally seen with CBS.
机译：胱天冬胺β-合酶（CBS）是硫氨基酸代谢的关键调节剂，通过反式硫化途径从甲硫氨酸循环从甲硫氨酸循环中的半胱氨酸循环到半胱氨酸的生物合成。 CBS也是H_（2）S生物发生的主要来源。据报道，CBS的作用是根据脑缺血，促进卵巢肿瘤生长，并通过控制氧化还原行为和调节线粒体生物植物学，维持耐药表型。反式硫化途径在真核生物中很好地保守，但是类似的酶在不同的生物中具有不同的酶促行为。来自较高生物的CBSS含有n末端域中的血红素。虽然血红素的存在尚未阐明其在CBS中的功能，但生物化学上有趣，它妨碍了吡哆醛5'-磷酸（PLP）物种的UV-Vis吸收光谱研究。来自酿酒酵母（YCBS）的CBS自然缺乏含血红的N-末端结构域，这使其成为催化酶法反应的光谱研究的理想模型，并允许基本YCBS催化核的结构研究（YCBS-CC） 。在这里，我们介绍了YCBS-CC的晶体结构，解决为1.5？。已经捕获了与酶反应中间体复合物中YCBS-CC的晶体结构，为催化参与的残留物提供了结构依据。最后，通过与抑制剂孵育产生的YCBS-CC Cofactor复合物的结构显示出明显的途径化学，通常用CBS看出。

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