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首页> 外文期刊>FEBS Open Bio >Biochemical and spectroscopic properties of Brucella microti glutamate decarboxylase, a key component of the glutamate-dependent acid resistance system
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Biochemical and spectroscopic properties of Brucella microti glutamate decarboxylase, a key component of the glutamate-dependent acid resistance system

机译：布鲁氏菌微量谷氨酸脱羧酶的生化和光谱性质，谷氨酸依赖性酸抗性系统的关键组成部分

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In orally acquired bacteria, the ability to counteract extreme acid stress (pH=<2.5) ensures survival during transit through the animal host stomach. In several neutralophilic bacteria, the glutamate-dependent acid resistance system (GDAR) is the most efficient molecular system in conferring protection from acid stress. In Escherichia coli its structural components are either of the two glutamate decarboxylase isoforms (GadA, GadB) and the antiporter, GadC, which imports glutamate and exports @c-aminobutyrate, the decarboxylation product. The system works by consuming protons intracellularly, as part of the decarboxylation reaction, and exporting positive charges via the antiporter. Herein, biochemical and spectroscopic properties of GadB from Brucella microti (BmGadB), a Brucella species which possesses GDAR, are described. B. microti belongs to a group of lately described and atypical brucellae that possess functional gadB and gadC genes, unlike the most well-known ''classical'' Brucella species, which include important human pathogens. BmGadB is hexameric at acidic pH. The pH-dependent spectroscopic properties and activity profile, combined with in silico sequence comparison with E. coli GadB (EcGadB), suggest that BmGadB has the necessary structural requirements for the binding of activating chloride ions at acidic pH and for the closure of its active site at neutral pH. On the contrary, cellular localization analysis, corroborated by sequence inspection, suggests that BmGadB does not undergo membrane recruitment at acidic pH, which was observed in EcGadB. The comparison of GadB from evolutionary distant microorganisms suggests that for this enzyme to be functional in GDAR some structural features must be preserved.
机译：在口服获得的细菌中，抵抗极端酸胁迫（pH = <2.5）的能力可确保在通过动物宿主胃的运输过程中存活。在几种嗜中性细菌中，谷氨酸依赖性酸抗性系统（GDAR）是最有效的分子系统，可提供对酸胁迫的保护。在大肠杆菌中，其结构成分是两种谷氨酸脱羧酶同工型（GadA，GadB）和反转运蛋白GadC之一，后者输入谷氨酸并输出脱羧化产物c-氨基丁酸酯。该系统通过在细胞内消耗质子（作为脱羧反应的一部分）并通过反转运蛋白输出正电荷而起作用。本文中，描述了来自具有GDAR的布鲁氏菌种布鲁氏菌的GadB的生化和光谱性质。微小芽孢杆菌属于一组最近描述的非典型布鲁氏菌，它们具有功能性gadB和gadC基因，这与最著名的“经典”布鲁氏菌种不同，后者包括重要的人类病原体。 BmGadB在酸性pH下为六聚体。 pH依赖的光谱特性和活性谱，再结合与大肠杆菌GadB（EcGadB）的计算机序列比较，表明BmGadB具有在酸性pH下结合活化氯离子并封闭其活性物质的必要结构要求。 pH中性位点。相反，通过序列检查证实了细胞定位分析，表明BmGadB在酸性pH下不发生膜募集，而在EcGadB中观察到。对来自进化远距离微生物的GadB的比较表明，要使该酶在GDAR中起作用，必须保留一些结构特征。

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