Structural and functional insights into metal coordination and substrate recognition of Akkermansia muciniphila sialidase Amuc_1547.

IF 6.3 Q1 BIOCHEMISTRY & MOLECULAR BIOLOGY
Tao Li, XinYue Tang, YiBo Zhu, NingLin Zhao, YingJie Song, Lihui He, XingYu Mou, Chunlei Ge, Zhenpu Chen, Hai Zhang, Xiaoxuan Yao, Xiaoyuan Hu, Jiaxing Cheng, Hong Yao, Rui Bao
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引用次数: 0

Abstract

Sialidases in Akkermansia muciniphila are pivotal for mucin degradation, enabling energy acquisition, modulating gut microbiota balance, and influencing host health. However, their structural and functional mechanisms remain poorly characterized. This study resolved the magnesium-bound crystal structure of Amuc_1547, revealing a six-bladed β-propeller fold linked to a carbohydrate-binding module (CBM)-like β-sandwich domain. Structural characterization ​identified a conserved S-x-D-x-G-x-x-W motif, a unique metal-binding pocket coordinated by residues Glu289, Glu299, and Asp300, and a putative carbohydrate substrate-binding pocket within the CBM-like domain. Enzymatic assays confirmed the functional relevance of these structural elements and demonstrated that both metal ions and glycans significantly enhance enzymatic activity. Molecular docking, dynamics simulations, and enzyme kinetics analysis identified critical residue substitutions involved in sialic acid substrate binding and catalysis: Gln367 replaces an arginine in the classical Arg-triplet, while Gln350 and His349 ​replace the nucleophilic tyrosine. These substitutions collectively mediate substrate binding, nucleophilic attack, and transition state stabilization, distinguishing the catalytic mechanism of Amuc_1547 from other six-bladed β-propeller sialidases. Additionally, comparative analysis of the four A. muciniphila sialidases highlights sequence divergence and domain architecture variations, suggesting niche-specific roles in gut microenvironments. Our work not only deciphers the structural basis of metal-dependent substrate recognition in Amuc_1547 but also advances our understanding of the adaptation of A. muciniphila to gut niches, offering a blueprint for leveraging sialidase-driven mucin metabolism in microbiota-targeted therapies.

嗜muciniphila唾液酸酶Amuc_1547的结构和功能研究
嗜粘杆菌唾液酸酶是粘蛋白降解、能量获取、调节肠道菌群平衡和影响宿主健康的关键。然而,它们的结构和功能机制仍不清楚。这项研究解析了Amuc_1547的镁结合晶体结构,揭示了一个与碳水化合物结合模块(CBM)类似的β-三明治结构域相连的六叶片β-螺旋桨褶皱。结构表征鉴定出一个保守的S-x-D-x-G-x-x-W基序,一个由Glu289, Glu299和Asp300残基协调的独特金属结合袋,以及一个假定的碳水化合物底物结合袋在cbm样结构域中。酶分析证实了这些结构元素的功能相关性,并证明金属离子和聚糖都能显著增强酶活性。分子对接、动力学模拟和酶动力学分析确定了参与唾液酸底物结合和催化的关键残基取代:Gln367取代了经典精氨酸三元组中的精氨酸,而Gln350和His349取代了亲核酪氨酸。这些取代共同介导底物结合、亲核攻击和过渡态稳定,将Amuc_1547的催化机制与其他六叶型β-螺旋桨唾液酸酶区分出来。此外,四种嗜粘杆菌唾液酸酶的比较分析突出了序列差异和结构域结构差异,表明它们在肠道微环境中具有特定的生态位作用。我们的工作不仅破解了Amuc_1547中金属依赖性底物识别的结构基础,而且还推进了我们对嗜粘杆菌对肠道生态位适应性的理解,为利用唾液酸酶驱动的粘蛋白代谢在微生物群靶向治疗中提供了蓝图。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
6.30
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