Heme Binding to Porphobilinogen Deaminase from Vibrio cholerae Decelerates the Formation of 1-Hydroxymethylbilane

Takeshi Uchida, Takumi Funamizu, Minghao Chen, Yoshikazu Tanaka, Koichiro Ishimori

    Research output: Contribution to journalArticle

    8 Citations (Scopus)

    Abstract

    Porphobilinogen deaminase (PBGD) is an enzyme that catalyzes the formation of hydroxymethylbilane, a tetrapyrrole intermediate, during heme biosynthesis through the stepwise polymerization of four molecules of porphobilinogen. PBGD from Vibrio cholerae was expressed in Escherichia coli and characterized in this study. Unexpectedly, spectroscopic measurements revealed that PBGD bound one equivalent of heme with a dissociation constant of 0.33 ± 0.01 μM. The absorption and resonance Raman spectra suggested that heme is a mixture of the 5-coordinate and 6-coordinate hemes. Mutational studies indicated that the 5-coordinate heme possessed Cys105 as a heme axial ligand, and His227 was coordinated to form the 6-coordinate heme. Upon heme binding, the deamination activity decreased by approximately 15%. The crystal structure of PBGD revealed that His227 was located near Cys105, but the side chain of His227 did not point toward Cys105. The addition of the cyanide ion to heme-PBGD abolished the effect of heme binding on the enzymatic activity. Therefore, coordination of His227 to heme appeared to induce reorientation of the domains containing Cys105, leading to a decrease in the enzymatic activity. This is the first report indicating that the PBGD activity is controlled by heme, the final product of heme biosynthesis. This finding improves our understanding of the mechanism by which heme biosynthesis is regulated.

    Original languageEnglish
    Pages (from-to)750-760
    Number of pages11
    JournalACS Chemical Biology
    Volume13
    Issue number3
    DOIs
    Publication statusPublished - 2018 Mar 16

    ASJC Scopus subject areas

    • Biochemistry
    • Molecular Medicine

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