title: Evidence for 4-hydroxyproline in viral proteins. Characterization of a viral prolyl 4-hydroxylase and its peptide substrates.
abstract: 4-Hydroxyproline, the characteristic amino acid of collagens and collagen-like proteins in animals, is also found in certain proline-rich proteins in plants but has been believed to be absent from viral and bacterial proteins. We report here on the cloning and characterization from a eukaryotic algal virus, Paramecium bursaria Chlorella virus-1, of a 242-residue polypeptide, which shows distinct sequence similarity to the C-terminal half of the catalytic alpha subunits of animal prolyl 4-hydroxylases. The recombinant polypeptide, expressed in Escherichia coli, was found to be a soluble monomer and to hydroxylate both (Pro-Pro-Gly)(10) and poly(L-proline), the standard substrates of animal and plant prolyl 4-hydroxylases, respectively. Synthetic peptides such as (Pro-Ala-Pro-Lys)(n), (Ser-Pro-Lys-Pro-Pro)(5), and (Pro-Glu-Pro-Pro-Ala)(5) corresponding to proline-rich repeats coded by the viral genome also served as substrates. (Pro-Ala-Pro-Lys)(10) was a particularly good substrate, with a K(m) of 20 microM. The prolines in both positions in this repeat were hydroxylated, those preceding the alanines being hydroxylated more efficiently. The data strongly suggest that P. bursaria Chlorella virus-1 expresses proteins in which many prolines become hydroxylated to 4-hydroxyproline by a novel viral prolyl 4-hydroxylase.
authors.affiliation: Collagen Research Unit, Biocenter and Department of Medical Biochemistry, University of Oulu, FIN-90401 Oulu, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Eriksson
authors.forename: J
authors.initials: J
authors.lastname: Myllyharju
authors.forename: H
authors.initials: H
authors.lastname: Tu
authors.forename: M
authors.initials: M
authors.lastname: Hellman
authors.forename: K I
authors.initials: KI
authors.lastname: Kivirikko
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D006900:Hydroxylation; D006909:Hydroxyproline / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010455:Peptides / Q000378:metabolism; D017862:Phycodnaviridae / Q000201:enzymology*; D011393:Procollagen-Proline Dioxygenase / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D011392:Proline / Q000378:metabolism*; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D020449:Repetitive Sequences, Amino Acid; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D010455:Peptides; D011994:Recombinant Proteins; D014764:Viral Proteins; D011392:Proline; D011393:Procollagen-Proline Dioxygenase; D006909:Hydroxyproline