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Structural and biochemical characterization of a glutathione transferase from the citrus canker pathogen Xanthomonas.
Acta Crystallographica Section D ( IF 2.2 ) Pub Date : 2020-08-03 , DOI: 10.1107/s2059798320009274
Eduardo Hilario 1 , Sawyer De Keyser 1 , Li Fan 1
Affiliation  

The genus Xanthomonas comprises several cosmopolitan plant‐pathogenic bacteria that affect more than 400 plant species, most of which are of economic interest. Citrus canker is a bacterial disease that affects citrus species, reducing fruit yield and quality, and is caused by the bacterium Xanthomonas citri subsp. citri (Xac). The Xac3819 gene, which has previously been reported to be important for citrus canker infection, encodes an uncharacterized glutathione S‐transferase (GST) of 207 amino‐acid residues in length (XacGST). Bacterial GSTs are implicated in a variety of metabolic processes such as protection against chemical and oxidative stresses. XacGST shares high sequence identity (45%) with the GstB dehalogenase from Escherichia coli O6:H1 strain CFT073 (EcGstB). Here, XacGST is reported to be able to conjugate glutathione (GSH) with bromoacetate with a Km of 6.67 ± 0.77 mM, a kcat of 42.69 ± 0.32 s−1 and a kcat/Km of 6.40 ± 0.72 mM−1 s−1 under a saturated GSH concentration (3.6 mM). These values are comparable to those previously reported for EcGstB. In addition, crystal structures of XacGST were determined in the apo form (PDB entry 6nxv) and in a GSH‐bound complex (PDB entry 6nv6). XacGST has a canonical GST‐like fold with a conserved serine residue (Ser12) at the GSH‐binding site near the N‐terminus, indicating XacGST to be a serine‐type GST that probably belongs to the theta‐class GSTs. GSH binding stabilizes a loop of about 20 residues containing a helix that is disordered in the apo XacGST structure.

中文翻译:

柑橘溃疡病病原体黄单胞菌谷胱甘肽转移酶的结构和生化特征。

黄单胞菌属由几种世界性植物病原菌组成,影响 400 多种植物物种,其中大多数具有经济利益。柑橘溃疡病是一种细菌性疾病,影响柑橘品种,降低果实产量和质量,由柑橘黄单胞菌亚种细菌引起。柑橘(Xac)。Xac3819 基因此前曾被报道对柑橘溃疡病感染很重要,它编码一种长度为 207 个氨基酸残基的未表征的谷胱甘肽S转移酶 (GST) (XacGST)。细菌 GST 参与多种代谢过程,例如抵御化学和氧化应激。XacGST 与大肠杆菌O6:H1 菌株 CFT073 (EcGstB)的 GstB 脱卤素酶具有高度序列同一性 (45%) 。据报道,XacGST 能够将谷胱甘肽 (GSH) 与溴乙酸结合,K m为 6.67 ± 0.77 m Mk cat为 42.69 ± 0.32 s -1,  k cat / K m为 6.40 ± 0.72 m M -1  s -1在饱和 GSH 浓度 (3.6 m M ) 下。这些值与之前报道的 EcGstB 值相当。此外,还确定了 XacGST 的 apo 形式(PDB 条目 6nxv)和 GSH 结合复合物(PDB 条目 6nv6)的晶体结构。XacGST 具有典型的 GST 样折叠,在 N 末端附近的 GSH 结合位点具有保守的丝氨酸残基 (Ser12),表明 XacGST 是丝氨酸型 GST,可能属于 theta 类 GST。GSH 结合可稳定包含约 20 个残基的环,其中包含载脂蛋白 XacGST 结构中无序的螺旋。
更新日期:2020-08-03
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