A novel form of cytochrome P-450 family 4 in human polymorphonuclear leukocytes: cDNA cloning and expression of leukotriene B4 ω-hydroxylase

Yasushi Kikuta, Emi Kusunose, Katsuya Endo, Satoru Yamamoto, Kazuhiro Sogawa, Yoshiaki Fujii-Kuriyama, Masamichi Kusunose

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    123 Citations (Scopus)

    Abstract

    Isolation of cDNA clones for human leukotriene B4 (LTB4) ω-hydroxylase clearly demonstrates that the hydroxylase is a member of the cytochrome P-450 (CYP) superfamily. cDNA clones isolated from a human leukocyte cDNA library with CYP4A4 cDNA as a probe encode a protein of 520 amino acids with a molecular weight of 59,805. The deduced amino acid sequence contains an invariant cysteine in the conserved heme-binding domain near the C terminus, characteristic of the P-450 superfamily. The microsomes from yeast cells transfected with an expression vector pAAH5 carrying isolated cDNA catalyzed the ω-hydroxylation of LTB4 with a Km value of 0.71 μM, and its activity was significantly inhibited by carbon monoxide and by antisera against CYP4A4, consistent with the properties previously reported with LTB4 ω-hydroxylase in human polymorphonuclear leukocytes. The amino acid sequence of LTB4 ω-hydroxylase (P-450LTBω) shows 31-44% similarity to those of CYP4A, CYP4B, and CYP4C, whereas less than 25% similarity was observed with any of the other P-450 families. According to the systematic classification of the P-450 superfamily, P-450LTBω is classified into the CYP4 family but does not belong to any of the known CYP4 subfamilies. This P-450 composes a new subfamily of CYP4. RNA blot analysis indicated that mRNA hybridized to the cDNA was expressed in the polymorphonuclear leukocytes as well as leukocytes from four individuals. Isolation of the cDNA opens the way to investigate the physiological role and to regulation of the ω-hydroxylase in the inflammation process.

    Original languageEnglish
    Pages (from-to)9376-9380
    Number of pages5
    JournalJournal of Biological Chemistry
    Volume268
    Issue number13
    Publication statusPublished - 1993 May 5

    ASJC Scopus subject areas

    • Biochemistry

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