9E6H

Cryo-EM structure of Maackia amurensis seed Leukoagglutinin (lectin), MASL

Summary for 9E6H

• Entry DOI: 10.2210/pdb9e6h/pdb
• EMDB information: 47565
• Descriptor: Seed leukoagglutinin, alpha-D-mannopyranose-(1-3)-beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, alpha-D-mannopyranose-(1-3)-[alpha-D-mannopyranose-(1-6)]beta-D-mannopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (6 entities in total)
• Functional Keywords: seed lectin, maackia amurensis, n-linked glycosylation, intersubunit disulphide bridge, leukoagglutinin, sugar binding protein
• Biological source: Maackia amurensis
• Total number of polymer chains: 4
• Total formula weight: 134073.67

Authors

Nayak, A.R.,Goldberg, G.S.,Temiakov, D. (deposition date: 2024-10-30, release date: 2025-04-09, Last modification date: 2025-05-07)

Primary citation

Nayak, A.R.,Holdcraft, C.J.,Yin, A.C.,Nicoletto, R.E.,Zhao, C.,Zheng, H.,Temiakov, D.,Goldberg, G.S.
Maackia amurensis seed lectin structure and sequence comparison with other M. amurensis lectins.
J.Biol.Chem., 301:108466-108466, 2025

PubMed Abstract: 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 non-cognate 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 Maackia amurensis lectins, offering a foundation for further exploration of its biological and therapeutic potential.

PubMed: 40158854
DOI: 10.1016/j.jbc.2025.108466

Experimental method

ELECTRON MICROSCOPY (2.84 Å)