title: Structural insights into the glycosyltransferase activity of the Actinobacillus pleuropneumoniae HMW1C-like protein.
abstract: Glycosylation of proteins is a fundamental process that influences protein function. The Haemophilus influenzae HMW1 adhesin is an N-linked glycoprotein that mediates adherence to respiratory epithelium, an essential early step in the pathogenesis of H. influenzae disease. HMW1 is glycosylated by HMW1C, a novel glycosyltransferase in the GT41 family that creates N-glycosidic linkages with glucose and galactose at asparagine residues and di-glucose linkages at sites of glucose modification. Here we report the crystal structure of Actinobacillus pleuropneumoniae HMW1C (ApHMW1C), a functional homolog of HMW1C. The structure of ApHMW1C contains an N-terminal all α-domain (AAD) fold and a C-terminal GT-B fold with two Rossmann-like domains and lacks the tetratricopeptide repeat fold characteristic of the GT41 family. The GT-B fold harbors the binding site for UDP-hexose, and the interface of the AAD fold and the GT-B fold forms a unique groove with potential to accommodate the acceptor protein. Structure-based functional analyses demonstrated that the HMW1C protein shares the same structure as ApHMW1C and provided insights into the unique bi-functional activity of HMW1C and ApHMW1C, suggesting an explanation for the similarities and differences of the HMW1C-like proteins compared with other GT41 family members.
authors: Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204.
authors: Fumihiro
authors: F
authors: Kawai
authors: Departments of Pediatrics and Molecular Genetics & Microbiology, Duke University Medical Center, Durham, North Carolina 27710.
authors: Susan
authors: S
authors: Grass
authors: Structural Biology Center, Argonne National Laboratory, Argonne, Illinois 60439.
authors: Youngchang
authors: Y
authors: Kim
authors: Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204.
authors: Kyoung-Jae
authors: KJ
authors: Choi
authors: Departments of Pediatrics and Molecular Genetics & Microbiology, Duke University Medical Center, Durham, North Carolina 27710.
authors: Joseph W
authors: JW
authors: St Geme
authors: Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204. Electronic address: hyeo@uh.edu.
authors: Hye-Jeong
authors: HJ
authors: Yeo
mesh_terms: D016977:Actinobacillus pleuropneumoniae / Q000378:metabolism*; D018829:Adhesins, Bacterial / Q000737:chemistry*; D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray / Q000379:methods; D006023:Glycoproteins / Q000737:chemistry; D006031:Glycosylation; D016695:Glycosyltransferases / Q000737:chemistry*; D006193:Haemophilus influenzae / Q000378:metabolism; D006601:Hexoses / Q000737:chemistry; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014530:Uridine Diphosphate / Q000737:chemistry
chemical_list: D018829:Adhesins, Bacterial; D006023:Glycoproteins; C117431:HMW1 protein, bacteria; D006601:Hexoses; D014530:Uridine Diphosphate; D016695:Glycosyltransferases