7zvj
From Proteopedia
Homodimeric structure of LARGE1
Structural highlights
DiseaseLARG1_HUMAN Congenital muscular dystrophy with intellectual disability;Walker-Warburg syndrome;Muscle-eye-brain disease. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. FunctionLARG1_HUMAN Bifunctional glycosyltransferase with both alpha-1,3-xylosyltransferase and beta-1,3-glucuronyltransferase activities involved in the maturation of alpha-dystroglycan (DAG1) by glycosylation leading to DAG1 binding to laminin G-like domain-containing extracellular proteins with high affinity (PubMed:15661757, PubMed:15752776, PubMed:21987822, PubMed:22223806, PubMed:23125099, PubMed:25279697, PubMed:25279699). Elongates the glucuronyl-beta-1,4-xylose-beta disaccharide primer structure initiated by B4GAT1 by adding repeating units [-3-Xylose-alpha-1,3-GlcA-beta-1-] to produce a heteropolysaccharide (PubMed:22223806, PubMed:23125099, PubMed:25138275, PubMed:25279697, PubMed:25279699, PubMed:32975514). Requires the phosphorylation of core M3 (O-mannosyl trisaccharide) by POMK to elongate the glucuronyl-beta-1,4-xylose-beta disaccharide primer (PubMed:21987822). Plays a key role in skeletal muscle function and regeneration (By similarity).[UniProtKB:Q9Z1M7][1] [2] [3] [4] [5] [6] [7] [8] [9] Publication Abstract from PubMedLARGE1 is a bifunctional glycosyltransferase responsible for generating a long linear polysaccharide termed matriglycan that links the cytoskeleton and the extracellular matrix and is required for proper muscle function. This matriglycan polymer is made with an alternating pattern of xylose and glucuronic acid monomers. Mutations in the LARGE1 gene have been shown to cause life-threatening dystroglycanopathies through the inhibition of matriglycan synthesis. Despite its major role in muscle maintenance, the structure of the LARGE1 enzyme and how it assembles in the Golgi are unknown. Here we present the structure of LARGE1, obtained by a combination of X-ray crystallography and single-particle cryo-EM. We found that LARGE1 homo-dimerizes in a configuration that is dictated by its coiled-coil stem domain. The structure shows that this enzyme has two canonical GT-A folds within each of its catalytic domains. In the context of its dimeric structure, the two types of catalytic domains are brought into close proximity from opposing monomers to allow efficient shuttling of the substrates between the two domains. Together, with putative retention of matriglycan by electrostatic interactions, this dimeric organization offers a possible mechanism for the ability of LARGE1 to synthesize long matriglycan chains. The structural information further reveals the mechanisms in which disease-causing mutations disrupt the activity of LARGE1. Collectively, these data shed light on how matriglycan is synthesized alongside the functional significance of glycosyltransferase oligomerization. Structural basis for matriglycan synthesis by the LARGE1 dual glycosyltransferase.,Katz M, Diskin R PLoS One. 2022 Dec 13;17(12):e0278713. doi: 10.1371/journal.pone.0278713. , eCollection 2022. PMID:36512577[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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