1vf8
The Crystal Structure of Ym1 at 1.31 A Resolution
Structural highlights
FunctionCHIL3_MOUSE Lectin that binds saccharides with a free amino group, such as glucosamine or galactosamine. Binding to oligomeric saccharides is much stronger than binding to mono- or disaccharides. Also binds chitin and heparin. Has weak hexosaminidase activity but no chitinase activity. Has chemotactic activity for T-lymphocytes, bone marrow cells and eosinophils. May play a role in inflammation and allergy.[1] [2] [3] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedUpon nematode infection, murine peritoneal macrophages synthesize and secrete large amounts of the Ym1 protein, which is a unique functional marker for alternatively activated macrophages in T(H)2-mediated inflammatory responses. Ym1 shares significant structural similarity to the family 18 chitinases. Previously, Ym1 has been studied with respect to its carbohydrate-binding ability and glycosyl hydrolysis activity and this has led to various inconclusive interpretations. Our present co-crystallization and soaking experiments with various glucosamine or N-acetylglucosamine oligomers yield only the uncomplexed Ym1. The refined Ym1 structure at 1.31A resolution clearly displays a water cluster forming an extensive hydrogen bond network with the "active-site" residues. This water cluster contributes notable electron density to lower resolution maps and this might have misled and given rise to a previous proposal for a monoglucosamine-binding site for Ym1. A structural comparison of family 18 glycosidase (-like) proteins reveals a lack of several conserved residues in Ym1, and illustrates the versatility of the divergent active sites. Therefore, Ym1 may lack N-acetylglucosamine-binding affinity, and this suggests that a new direction should be taken to unravel the function of Ym1. The crystal structure of Ym1 at 1.31 A resolution.,Tsai ML, Liaw SH, Chang NC J Struct Biol. 2004 Dec;148(3):290-6. PMID:15522777[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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