National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
NIH GM131832
米国
引用
ジャーナル: J Biol Chem / 年: 2025 タイトル: Maackia amurensis seed lectin structure and sequence comparison with other M. amurensis lectins. 著者: Ashok R Nayak / Cayla J Holdcraft / Ariel C Yin / Rachel E Nicoletto / Caifeng Zhao / Haiyan Zheng / Dmitry Temiakov / Gary S Goldberg / 要旨: Maackia amurensis lectins, including MASL, MAA, and MAL2, are widely utilized in biochemical and medicinal research. However, the structural and functional differences between these lectins have not ...Maackia amurensis lectins, including MASL, MAA, and MAL2, are widely utilized in biochemical and medicinal research. However, the structural and functional differences between these lectins have not been defined. Here, we present a high-resolution cryo-EM structure of MASL revealing that its tetrameric assembly is directed by two intersubunit disulfide bridges. These bridges, formed by C272 residues, are central to the dimer-of-dimers assembly of a MASL tetramer. This cryo-EM structure also identifies residues involved in stabilizing the dimer interface, multiple glycosylation sites, and calcium and manganese atoms in the sugar-binding pockets of MASL. Notably, our analysis reveals that Y250 in the carbohydrate-binding site of MASL adopts a flipped conformation, likely acting as a gatekeeper that obstructs access to noncognate substrates, a feature that may contribute to MASL's substrate specificity. Sequence analysis suggests that MAA is a truncated version of MASL, while MAL2 represents a homologous isoform. Unlike MASL, neither MAL2 nor MAA contains a cysteine residue required for disulfide bridge formation. Accordingly, analysis of these proteins using reducing and nonreducing SDS-PAGE confirms that the C272 residue in MASL drives intermolecular disulfide bridge formation. These findings provide critical insights into the unique structural features of MASL that distinguish it from other M. amurensis lectins, offering a foundation for further exploration of its biological and therapeutic potential.
凍結剤: ETHANE / チャンバー内湿度: 95 % / チャンバー内温度: 277 K / 装置: FEI VITROBOT MARK IV
詳細
3 uM MASL monodisperse solution
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電子顕微鏡法
顕微鏡
TFS GLACIOS
特殊光学系
詳細: No Energy filter was used
ソフトウェア
名称: EPU (ver. 3.6)
詳細
Calibrated pixel size -0.93
撮影
フィルム・検出器のモデル: FEI FALCON IV (4k x 4k) 撮影したグリッド数: 1 / 実像数: 8543 / 平均電子線量: 60.0 e/Å2 詳細: Total number of frames - 40, Defocus range - -0.3 to -1.2 um in 0.1 increments, Output mode - TIFF, Autofocus recurrence - after centering, Drift measurement - once per grid square (Threshold - 0.4 nm/sec)