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首页> 外文期刊>Acta crystallographica.Section D. Biological crystallography >The narrow active-site cleft of O-acetylserine sulfhydrylase from Leishmania donovani allows complex formation with serine acetyltransferases with a range of C-terminal sequences
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The narrow active-site cleft of O-acetylserine sulfhydrylase from Leishmania donovani allows complex formation with serine acetyltransferases with a range of C-terminal sequences

机译：狭窄的活性部位间隙O-acetylserinesulfhydrylase杜氏利什曼虫允许复杂地层与丝氨酸乙酰转移酶与一系列c端序列

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摘要

Cysteine is a crucial substrate for the synthesis of glutathione and trypanothione, which in turn maintain intracellular redox homeostasis and defend against oxidative stress in the pathogen Leishmania donovani. Here, the identification, sequencing, characterization and crystal structure at 1.79 ? resolution of O-acetylserine sulfhydrylase (OASS), a cysteine-biosynthetic pathway enzyme from L. donovani (LdOASS), are reported. It shows binding to the serine acetyltransferase (SAT) C-terminal peptide, indicating that OASS and SAT interact with each other to form a cysteine synthase complex, further confirmed by the structure of LdOASS in complex with SAT C-terminal octapeptide at 1.68 ? resolution. Docking and fluorescence binding studies show that almost all SAT C - terminus mimicking tetrapeptides can bind to LdOASS. Some peptides had a higher binding affinity than the native peptide, indicating that SAT-OASS interactions are not sequence-specific. The structure of LdOASS with a designed peptide (DWSI) revealed that LdOASS makes more inter-actions with the designed peptide than with the native peptide. In almost all known SAT-OASS interactions the SAT C - terminal sequence was shown to contain amino acids with large side chains. Structural comparison with other OASSs revealed that LdOASS has a relatively less open active-site cleft, which may be responsible for its interaction with the smaller-amino-acid-containing C-terminal LdSAT peptide. Biochemical studies confirmed that LdOASS interacts with SATs from Entamoeba histolytica and Brucella abortus, further displaying its sequence-independent and versatile mode of interaction with SATs. This implicates a critical role of the size of the active-site cleft opening in OASS for SAT-OASS inter-action and thus cysteine synthase complex formation.
机译：半胱氨酸是一种至关重要的底物合成谷胱甘肽和trypanothione,反过来维持细胞内氧化还原内稳态抵御病原体的氧化应激杜氏利什曼虫。测序、表征、晶体结构在1.79吗?cysteine-biosynthetic sulfhydrylase (oas)从l . donovani途径酶(LdOASS)报道。乙酰转移酶(坐)c端肽,表明,美洲国家组织,坐在相互其他形成半胱氨酸合成酶复杂,进一步证实了LdOASS的结构复杂的c端八肽坐在1.68吗?决议。研究表明,几乎所有的C -末端坐下LdOASS模仿四肽可以绑定。肽有较高的亲和力比原生肽,表明SAT-OASS不是sequence-specific的交互。LdOASS结构设计的肽(DWSI)透露,LdOASS更inter-actions肽与设计本机肽。坐在C -末端序列的交互显示包含氨基酸与大的一面链。透露,LdOASS相对不那么开放活性部位裂缝,这可能是负责其相互作用smaller-amino-acid-containing c端LdSAT肽。从痢疾LdOASS与sat考试阿米巴和流产布鲁,进一步显示其sequence-independent和多才多艺与sat模式交互。关键作用的活性部位的大小裂在美洲国家组织开放SAT-OASS相互作用因此半胱氨酸合成酶复杂的形成。

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