Cloning and characterization of a third human lysyl hydroxylase isoform.
Lysyl hydroxylase (EC 1.14.11.4), a homodimer, catalyzes the formation of hydroxylysine in collagens. Recently, an isoenzyme termed lysyl hydroxylase 2 has been cloned from human sources [M. Valtavaara, H. Papponen, A.-M. Pirttilä, K. Hiltunen, H. Helander and R. Myllylä (1997) J. Biol. Chem. 272, 6831-6834]. We report here on the cloning of a third human lysyl hydroxylase isoenzyme, termed lysyl hydroxylase 3. The cDNA clones encode a 738 amino acid polypeptide, including a signal peptide of 24 residues. The overall amino acid sequence identity between the processed human lysyl hydroxylase 3 and 1 polypeptides is 59%, and that between the processed lysyl hydroxylase 3 and 2 polypeptides is 57%, whereas the identity to the processed Caenorhabditis elegans polypeptide is only 45%. All four recently identified critical residues at the catalytic site, two histidines, one aspartate, and one arginine, are conserved in all these polypeptides. The mRNA for lysyl hydroxylase 3 was found to be expressed in a variety of tissues, but distinct differences appear to exist in the expression patterns of the three isoenzyme mRNAs. Recombinant lysyl hydroxylase 3 expressed in insect cells by means of a baculovirus vector was found to be more soluble than lysyl hydroxylase 1 expressed in the same cell type. No differences in catalytic properties were found between the recombinant lysyl hydroxylase 3 and 1 isoenzymes. Deficiency in lysyl hydroxylase 1 activity is known to cause the type VI variant of the Ehlers-Danlos syndrome, and it is therefore possible that deficiency in lysyl hydroxylase 3 activity may lead to some other variant of this syndrome or to some other heritable connective tissue disorder.
Passoja
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Collagen Research Unit, Biocenter and Department of Medical Biochemistry, University of Oulu, FIN-90220 Oulu, Finland.
Rautavuoma
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Ala-Kokko
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Kosonen
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Kivirikko
K I
KI
D000595:Amino Acid Sequence; D000818:Animals; D017173:Caenorhabditis elegans / Q000201:enzymology; D002384:Catalysis; D003001:Cloning, Molecular; D018076:DNA, Complementary; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D017924:Nucleopolyhedroviruses / Q000235:genetics; D008240:Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D018411:Spodoptera
D018076:DNA, Complementary; D007527:Isoenzymes; D012333:RNA, Messenger; D011994:Recombinant Proteins; D008240:Procollagen-Lysine, 2-Oxoglutarate 5-Dioxygenase