title: O-fucosylation of thrombospondin type 1 repeats in ADAMTS-like-1/punctin-1 regulates secretion: implications for the ADAMTS superfamily.
abstract: The ADAMTS superfamily contains several metalloproteases (ADAMTS proteases) as well as ADAMTS-like molecules that lack proteolytic activity. Their common feature is the presence of one or more thrombospondin type-1 repeats (TSRs) within a characteristic modular organization. ADAMTS like-1/punctin-1 has four TSRs. Previously, O-fucosylation on Ser or Thr mediated by the endoplasmic reticulum-localized enzyme protein-O-fucosyltransferase 2 (POFUT2) was described for TSRs of thrombospondin-1, properdin, and F-spondin within the sequence Cys-Xaa(1)-Xaa(2)-(Ser/Thr)-Cys-Xaa-Xaa-Gly (where the fucosylated residue is underlined). On mass spectrometric analysis of tryptic peptides from recombinant secreted human punctin-1, the appropriate peptides from TSR2, TSR3, and TSR4 were found to bear either a fucose monosaccharide (TSR3, TSR4) or a fucose-glucose disaccharide (TSR2, TSR3, TSR4). Although mass spectral analysis did not unambiguously identify the relevant peptide from TSR1, metabolic labeling of cells expressing TSR1 and the cysteine-rich module led to incorporation of [(3)H]fucose into this construct. Mutation of the putative modified Ser/Thr residues in TSR2, TSR3, and TSR4 led to significantly decreased levels of secreted punctin-1. Similarly, expression of punctin-1 in Lec-13 cells that are deficient in conversion of GDP-mannose to GDP-fucose substantially decreased the levels of secreted protein, which were restored upon culture in the presence of exogenous l-fucose. In addition, mutation of the single N-linked oligosaccharide in punctin-1 led to decreased levels of secreted punctin-1. Taken together, the data define a critical role for N-glycosylation and O-fucosylation in the biosynthesis of punctin-1. From a broad perspective, these data suggest that O-fucosylation may be a widespread post-translational modification in members of the ADAMTS superfamily with possible regulatory consequences.
authors: Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
authors: Lauren W
authors: LW
authors: Wang
authors: Malgosia
authors: M
authors: Dlugosz
authors: Robert P T
authors: RP
authors: Somerville
authors: Mona
authors: M
authors: Raed
authors: Robert S
authors: RS
authors: Haltiwanger
authors: Suneel S
authors: SS
authors: Apte
mesh_terms: D000071096:ADAMTS Proteins; D000595:Amino Acid Sequence; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005643:Fucose / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019700:Thrombospondin 1 / Q000378:metabolism*
chemical_list: C454120:ADAMTSL1 protein, human; D016326:Extracellular Matrix Proteins; D011994:Recombinant Proteins; D019700:Thrombospondin 1; D005643:Fucose; D000071096:ADAMTS Proteins