Characterization of a novel Caenorhabditis elegans prolyl 4-hydroxylase with a unique substrate specificity and restricted expression in the pharynx and excretory duct

Keskiaho, K., Kukkola, L., Page, A. P. , Winter, A. D., Vuoristo, J., Sormunen, R., Nissi, R., Riihimaa, P. and Myllyharju, J. (2008) Characterization of a novel Caenorhabditis elegans prolyl 4-hydroxylase with a unique substrate specificity and restricted expression in the pharynx and excretory duct. Journal of Biological Chemistry, 283(16), pp. 10679-10689. (doi: 10.1074/jbc.M800972200)

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Publisher's URL: http://dx.doi.org/10.1074/jbc.M800972200

Abstract

Collagen prolyl 4-hydroxylases (C-P4Hs) have a critical role in collagen synthesis, since 4-hydroxyproline residues are necessary for folding of the triple-helical molecules. Vertebrate C-P4Hs are α<sub>2</sub>β<sub>2</sub> tetramers in which the β subunit is identical to protein-disulfide isomerase (PDI). Three isoforms of the catalytic α subunit, PHY-1, PHY-2, and PHY-3, have been characterized from Caenorhabditis elegans, PHY-1 and PHY-2 being responsible for the hydroxylation of cuticle collagens, whereas PHY-3 is predicted to be involved in collagen synthesis in early embryos. We have characterized transcripts of two additional C. elegans α subunit-like genes, Y43F8B.4 and C14E2.4. Three transcripts were generated from Y43F8B.4, and a polypeptide encoded by one of them, named PHY-4.1, assembled into active (PHY-4.1)<sub>2</sub>/(PDI-2)<sub>2</sub> tetramers and PHY-4.1/PDI-2 dimers when coexpressed with C. elegans PDI-2 in insect cells. The C14E2.4 transcript was found to have a frameshift leading to the absence of codons for two residues critical for P4H catalytic activity. Thus, C. elegans has altogether four functional C-P4H α subunits, PHY-1, PHY-2, PHY-3, and PHY-4.1. The tetramers and dimers containing recombinant PHY-4.1 had a distinct substrate specificity from the other C-P4Hs in that they hydroxylated poly(L-proline) and certain other proline-rich peptides, including ones that are expressed in the pharynx, in addition to collagen-like peptides. These data and the observed restricted expression of the phy-4.1 transcript and PHY-4.1 polypeptide in the pharyngeal gland cells and the excretory duct suggest that in addition to collagens, PHY-4.1 may hydroxylate additional proline-rich proteins in vivo.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Page, Professor Tony and Winter, Dr Alan
Authors: Keskiaho, K., Kukkola, L., Page, A. P., Winter, A. D., Vuoristo, J., Sormunen, R., Nissi, R., Riihimaa, P., and Myllyharju, J.
Subjects:Q Science > QH Natural history > QH345 Biochemistry
College/School:College of Medical Veterinary and Life Sciences
College of Medical Veterinary and Life Sciences > Institute of Infection Immunity and Inflammation
Journal Name:Journal of Biological Chemistry
Journal Abbr.:J Biol Chem.
Publisher:American Society for Biochemistry and Molecular Biology, Inc.
ISSN:0021-9258
ISSN (Online):1083-351X
Published Online:13 February 2008
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
229991The Molecular Enzymology of Collagen Assembly and Post-Translational Modification: a Nematode Model SystemAntony PageMedical Research Council (MRC)G117/290Infection Immunity and Inflammation Life Sciences
229993The Molecular Enzymology of Collagen Assembly and Post-Translational Modification: a Nematode Model SystemAntony PageMedical Research Council (MRC)G117/476III - PARASITOLOGY