Chlorophyll synthesis

    Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

    Abstract

    Chlorophyll is the dominant pigment in a mature plant cell, whether in the leaf of a plant or in the abundant algal species. Chlorophyll is synthesized within the chloroplast from a plentiful precursor, the amino acid glutamate. From glutamate to the tetrapyrrole protoporphyrin IX, at which the pathway branches between chlorophyll and heme, the reactions occur in the plastid stroma and are catalyzed by soluble enzymes. The latter steps to chlorophyll, the first being the insertion of the central magnesium atom, occur with enzyme complexes that are at least partially if not entirely localized on membranes. Magnesium chelatase, the key enzyme in this pathway, is a complex of proteins that includes soluble and membrane-bound subunits. Subsequent reactions occur primarily on membranes and involve modification of structural groups on the periphery of the molecule. The pentultimate precursor of chlorophyll, protochlorophyllide, is reduced by NADPH to chlorophyllide in the only reaction in the pathway that requires light. This reaction, which in angiosperms is catalyzed by light-dependent NADPH:protochlorophyllide oxidoreductase, dramatically changes the property of the molecule and allows the product chlorophyllide, and its esterified product, chlorophyll, to interact with proteins. These chlorophyll-protein complexes become the building blocks of the photosynthetic apparatus. The biosynthetic pathway is tightly regulated, particularly at the key reactions that generate 5-aminolevulinic acid, magnesium-protoporphyrin IX and chlorophyllide. Expression of genes encoding critical enzymes is usually regulated markedly by light, and the activities of the enzymes are also regulated by end-products in typical feedback inhibition.
    Original languageEnglish
    Title of host publicationThe Structure and function of plastids
    EditorsRobert R. Wise, J. Kenneth Hoober
    Place of PublicationDordrecht, The Netherlands
    PublisherSpringer, Springer Nature
    Pages295-313
    Number of pages19
    ISBN (Print)9781402040610
    DOIs
    Publication statusPublished - 2006

    Publication series

    NameAdvances in photosynthesis and respiration
    PublisherSpringer
    Volume23
    ISSN (Print)1572-0233

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