Like-acetylglucosaminyltransferase (LARGE)-dependent modification of dystroglycan at Thr-317/319 is required for laminin binding and arenavirus infection.

ABSTRACT: ?-dystroglycan is a highly O-glycosylated extracellular matrix receptor that is required for anchoring of the basement membrane to the cell surface and for the entry of Old World arenaviruses into cells. Like-acetylglucosaminyltransferase (LARGE) is a key molecule that binds to the N-terminal domain of ?-dystroglycan and attaches ligand-binding moieties to phosphorylated O-mannose on ?-dystroglycan. Here we show that the LARGE modification required for laminin- and virus-binding occurs on specific Thr residues located at the extreme N terminus of the mucin-like domain of ?-dystroglycan. Deletion and mutation analyses demonstrate that the ligand-binding activity of ?-dystroglycan is conferred primarily by LARGE modification at Thr-317 and -319, within the highly conserved first 18 amino acids of the mucin-like domain. The importance of these paired residues in laminin-binding and clustering activity on myoblasts and in arenavirus cell entry is confirmed by mutational analysis with full-length dystroglycan. We further demonstrate that a sequence of five amino acids, Thr(317)ProThr(319)ProVal, contains phosphorylated O-glycosylation and, when modified by LARGE is sufficient for laminin-binding. Because the N-terminal region adjacent to the paired Thr residues is removed during posttranslational maturation of dystroglycan, our results demonstrate that the ligand-binding activity resides at the extreme N terminus of mature ?-dystroglycan and is crucial for ?-dystroglycan to coordinate the assembly of extracellular matrix proteins and to bind arenaviruses on the cell surface.

SUBMITTER: Hara Y 

PROVIDER: S-EPMC3198351 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature