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Structural and Biochemical Insights into the Function and Evolution of Sulfoquinovosidases
ACS Central Science ( IF 18.2 ) Pub Date : 2018-09-05 00:00:00 , DOI: 10.1021/acscentsci.8b00453
Palika Abayakoon 1 , Yi Jin 2 , James P Lingford 3, 4 , Marija Petricevic 1 , Alan John 3, 4 , Eileen Ryan 1 , Janice Wai-Ying Mui 1 , Douglas E V Pires 5 , David B Ascher 5 , Gideon J Davies 2 , Ethan D Goddard-Borger 3, 4 , Spencer J Williams 1
Affiliation  

An estimated 10 billion tonnes of sulfoquinovose (SQ) are produced and degraded each year. Prokaryotic sulfoglycolytic pathways catabolize sulfoquinovose (SQ) liberated from plant sulfolipid, or its delipidated form α-d-sulfoquinovosyl glycerol (SQGro), through the action of a sulfoquinovosidase (SQase), but little is known about the capacity of SQ glycosides to support growth. Structural studies of the first reported SQase (Escherichia coli YihQ) have identified three conserved residues that are essential for substrate recognition, but crossover mutations exploring active-site residues of predicted SQases from other organisms have yielded inactive mutants casting doubt on bioinformatic functional assignment. Here, we show that SQGro can support the growth of E. coli on par with d-glucose, and that the E. coli SQase prefers the naturally occurring diastereomer of SQGro. A predicted, but divergent, SQase from Agrobacterium tumefaciens proved to have highly specific activity toward SQ glycosides, and structural, mutagenic, and bioinformatic analyses revealed the molecular coevolution of catalytically important amino acid pairs directly involved in substrate recognition, as well as structurally important pairs distal to the active site. Understanding the defining features of SQases empowers bioinformatic approaches for mapping sulfur metabolism in diverse microbial communities and sheds light on this poorly understood arm of the biosulfur cycle.

中文翻译:

Sulfoquinovosidases 的功能和进化的结构和生化见解

估计每年生产和降解 100 亿吨磺基喹诺糖 (SQ)。原核磺基糖酵解途径通过磺基喹诺糖苷酶 (SQase) 的作用分解代谢从植物硫脂或其脱脂形式 α - d-磺基喹诺糖基甘油 (SQGro) 中释放的磺基喹诺糖 (SQ),但对 SQ 糖苷支持生长的能力知之甚少. 对第一个报道的 SQase(大肠杆菌YihQ)的结构研究已经确定了三个对底物识别至关重要的保守残基,但是探索来自其他生物体的预测 SQase 的活性位点残基的交叉突变产生了对生物信息学功能分配产生怀疑的非活性突变体。在这里,我们证明 SQGro 可以支持大肠杆菌的生长d-葡萄糖相当,并且大肠杆菌SQase 更喜欢天然存在的 SQGro 非对映异构体。来自根癌农杆菌的预测但不同的 SQase被证明对 SQ 糖苷具有高度特异性活性,并且结构、诱变和生物信息学分析揭示了直接参与底物识别的重要催化氨基酸对以及结构上重要的氨基酸对的分子共同进化远离活动部位。了解 SQases 的定义特征为绘制不同微生物群落中硫代谢的生物信息学方法提供了支持,并阐明了对生物硫循环这一知之甚少的分支。
更新日期:2018-09-05
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