Ent-copalyl diphosphate synthase
Encyclopedia
In enzymology, an ent-copalyl diphosphate synthase is an enzyme
that catalyzes
the chemical reaction
:
Hence, this enzyme has one substrate
, geranylgeranyl pyrophosphate
, and one product
, ent-copalyl pyrophosphate. This enzyme participates in gibberellin
biosynthesis
.
This enzyme belongs to the family of isomerase
s, specifically the class of intramolecular lyase
s. The systematic name of this enzyme class is ent-copalyl-diphosphate lyase (decyclizing). Other names in common use include ent-kaurene synthase A, and ent-kaurene synthetase A.
and moss
es also have a distinct ent-kaurene synthase
activity associated with the same protein molecule. The reaction catalyzed by ent-kaurene synthase is the next step in the biosynthetic pathway to gibberellins. The two types of enzymic activity are distinct, and site-directed mutagenesis
to suppress the ent-kaurene synthase activity of the protein leads to build up of ent-copalyl pyrophosphate. Inhibition of ent-kaurene synthase activity, by replacing Mg2+ in the growth medium with Ni2+, has the same effect.
Higher plants typically have separate proteins for ent-copalyl diphosphate synthase and ent-kaurene synthase, although these may be associated as weakly bound dimers or enzyme complexes. Rice (Oryza sativa
) has two distinct ent-copalyl diphosphate synthases, which participate in distinct metabolic pathways. Only one ent-copalyl diphosphate synthase has been isolated from a bacterial species (Streptomyces
sp. strain KO-3988): it is also monofunctional.
As might be expected, the bifunctional enzymes from lower plants are larger (946–960 residues, 106–107 kDa) than the monofunctional enzymes from higher plants (800–867 residues, 90–98 kDa), although not by twice as much.The independent ent-kaurene synthases in higher plants, of which there may be several per species, are much more heterogenous in size, ranging 161–816 residues, 19–94 kDa. Source: BRENDA.
, hypocotyl
and root
s of sunflowers (Helianthus annuus) and Cucamonga manroot (Marah macrocarpus
); endosperm
of squash (Cucurbita maxima
) and manroot (M. macrocarpus); and leaves
of rice (Oryza sativa
). It has been localized to the chloroplast stroma
in peas (Pisum sativum) and wheat (Triticum aestivum).
The reaction catalyzed by ent-copalyl diphosphate synthase can be seen as the first committed step in gibberellin
biosynthesis. Gibberellins form an important group of plant hormones, with various functions in different species and at different stages of the plant's lifetime. Disorders in gibberellin biosynthesis commonly show themselves as growth disorders, particularly as dwarfism, and some of those can be traced to reduced ent-copalyl diphosphate synthase activity. The importance of ent-copalyl diphosphate synthase in plant hormone production – primary metabolism
– explains its widespread distribution both among species and among different plant tissues.
However, gibberellins are not the only phytochemicals produced from ent-copalyl pyrophosphate. A wide range of secondary metabolite
s, both terpene
s and alkaloid
s, are also derived either from ent-copalyl pyrophosphate itself or from ent-kaurene or ent-kaurenoic acid, the next two intermediates on the metabolic pathway to gibberellins. Knowledge of these secondary metabolic pathways is much less extensive that that of gibberellin biosynthesis, and is often little more than conjecture.Such conjecture is not, of course, without evidence. It can be clear from the structure of a secondary metabolite that it is almost certainly derived from ent-copalyl pyrophosphate without knowing the details of how the transformation is carried out in living plants.
It is known that ent-copalyl diphosphate synthase is produced by maize plants (Zea mays) in response to attack by Fusarium
fungi, which suggests that it might play a role in plant defences as a precursor to phytoalexin
s (defensive compounds produced by the plant). Rice plants produce (at least) two different types of ent-copalyl diphosphate synthase, and only one of those participates in the production of gibberellins, suggesting again that the other is involved in the production of phytoalexins.
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
that catalyzes
Catalysis
Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....
the chemical reaction
Chemical reaction
A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...
:
Hence, this enzyme has one substrate
Substrate (biochemistry)
In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate. In the case of a single substrate, the substrate binds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or...
, geranylgeranyl pyrophosphate
Geranylgeranyl pyrophosphate
Geranylgeranyl pyrophosphate is an intermediate in the HMG-CoA reductase pathway used by organisms in the biosynthesis of terpenes and terpenoids. In plants it is also the precursor to carotenoids, gibberellins, tocopherols, and chlorophylls....
, and one product
Product (chemistry)
Product are formed during chemical reactions as reagents are consumed. Products have lower energy than the reagents and are produced during the reaction according to the second law of thermodynamics. The released energy comes from changes in chemical bonds between atoms in reagent molecules and...
, ent-copalyl pyrophosphate. This enzyme participates in gibberellin
Gibberellin
Gibberellins are plant hormones that regulate growth and influence various developmental processes, including stem elongation, germination, dormancy, flowering, sex expression, enzyme induction, and leaf and fruit senescence....
biosynthesis
Biosynthesis
Biosynthesis is an enzyme-catalyzed process in cells of living organisms by which substrates are converted to more complex products. The biosynthesis process often consists of several enzymatic steps in which the product of one step is used as substrate in the following step...
.
This enzyme belongs to the family of isomerase
Isomerase
In biochemistry, an isomerase is an enzyme that catalyzes the structural rearrangement of isomers. Isomerases thus catalyze reactions of the formwhere B is an isomer of A.-Nomenclature:...
s, specifically the class of intramolecular lyase
Lyase
In biochemistry, a lyase is an enzyme that catalyzes the breaking of various chemical bonds by means other than hydrolysis and oxidation, often forming a new double bond or a new ring structure...
s. The systematic name of this enzyme class is ent-copalyl-diphosphate lyase (decyclizing). Other names in common use include ent-kaurene synthase A, and ent-kaurene synthetase A.
Bifunctionality
ent-Copalyl diphosphate synthases from fungiFungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
and moss
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
es also have a distinct ent-kaurene synthase
Ent-kaurene synthase
In enzymology, an ent-kaurene synthase is an enzyme that catalyzes the chemical reactionHence, this enzyme has one substrate, ent-copalyl diphosphate, and two products, ent-kaurene and diphosphate....
activity associated with the same protein molecule. The reaction catalyzed by ent-kaurene synthase is the next step in the biosynthetic pathway to gibberellins. The two types of enzymic activity are distinct, and site-directed mutagenesis
Site-directed mutagenesis
Site-directed mutagenesis, also called site-specific mutagenesis or oligonucleotide-directed mutagenesis, is a molecular biology technique in which a mutation is created at a defined site in a DNA molecule. In general, this form of mutagenesis requires that the wild type gene sequence be known...
to suppress the ent-kaurene synthase activity of the protein leads to build up of ent-copalyl pyrophosphate. Inhibition of ent-kaurene synthase activity, by replacing Mg2+ in the growth medium with Ni2+, has the same effect.
Higher plants typically have separate proteins for ent-copalyl diphosphate synthase and ent-kaurene synthase, although these may be associated as weakly bound dimers or enzyme complexes. Rice (Oryza sativa
Oryza sativa
Oryza sativa, commonly known as Asian rice, is the plant species most commonly referred to in English as rice. Oryza sativa is the cereal with the smallest genome, consisting of just 430Mb across 12 chromosomes...
) has two distinct ent-copalyl diphosphate synthases, which participate in distinct metabolic pathways. Only one ent-copalyl diphosphate synthase has been isolated from a bacterial species (Streptomyces
Streptomyces
Streptomyces is the largest genus of Actinobacteria and the type genus of the family Streptomycetaceae. Over 500 species of Streptomyces bacteria have been described. As with the other Actinobacteria, streptomycetes are gram-positive, and have genomes with high guanine and cytosine content...
sp. strain KO-3988): it is also monofunctional.
As might be expected, the bifunctional enzymes from lower plants are larger (946–960 residues, 106–107 kDa) than the monofunctional enzymes from higher plants (800–867 residues, 90–98 kDa), although not by twice as much.The independent ent-kaurene synthases in higher plants, of which there may be several per species, are much more heterogenous in size, ranging 161–816 residues, 19–94 kDa. Source: BRENDA.
Localization and function
ent-Copalyl diphosphate synthase has been isolated from a number of tissues in higher plants: cotyledonCotyledon
A cotyledon , is a significant part of the embryo within the seed of a plant. Upon germination, the cotyledon may become the embryonic first leaves of a seedling. The number of cotyledons present is one characteristic used by botanists to classify the flowering plants...
, hypocotyl
Hypocotyl
The hypocotyl is the stem of a germinating seedling, found below the cotyledons and above the radicle .-Dicots:...
and root
Root
In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial or aerating . Furthermore, a stem normally occurring below ground is not exceptional either...
s of sunflowers (Helianthus annuus) and Cucamonga manroot (Marah macrocarpus
Marah macrocarpus
Marah macrocarpus, the Cucamonga Manroot or Bigroot, is the common manroot of most of Southern California and Baja California.-Foliage:...
); endosperm
Endosperm
Endosperm is the tissue produced inside the seeds of most flowering plants around the time of fertilization. It surrounds the embryo and provides nutrition in the form of starch, though it can also contain oils and protein. This makes endosperm an important source of nutrition in human diet...
of squash (Cucurbita maxima
Cucurbita maxima
Cucurbita maxima, one of at least five species of cultivated squash, is one of the most diverse domesticated species, perhaps with more cultivated forms than any other crop. This species originated in South America from the wild C. maxima ssp. andreana over 4000 years ago...
) and manroot (M. macrocarpus); and leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
of rice (Oryza sativa
Oryza sativa
Oryza sativa, commonly known as Asian rice, is the plant species most commonly referred to in English as rice. Oryza sativa is the cereal with the smallest genome, consisting of just 430Mb across 12 chromosomes...
). It has been localized to the chloroplast stroma
Chloroplast
Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis.Chloroplasts are green...
in peas (Pisum sativum) and wheat (Triticum aestivum).
The reaction catalyzed by ent-copalyl diphosphate synthase can be seen as the first committed step in gibberellin
Gibberellin
Gibberellins are plant hormones that regulate growth and influence various developmental processes, including stem elongation, germination, dormancy, flowering, sex expression, enzyme induction, and leaf and fruit senescence....
biosynthesis. Gibberellins form an important group of plant hormones, with various functions in different species and at different stages of the plant's lifetime. Disorders in gibberellin biosynthesis commonly show themselves as growth disorders, particularly as dwarfism, and some of those can be traced to reduced ent-copalyl diphosphate synthase activity. The importance of ent-copalyl diphosphate synthase in plant hormone production – primary metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
– explains its widespread distribution both among species and among different plant tissues.
However, gibberellins are not the only phytochemicals produced from ent-copalyl pyrophosphate. A wide range of secondary metabolite
Secondary metabolite
Secondary metabolites are organic compounds that are not directly involved in the normal growth, development, or reproduction of an organism. Unlike primary metabolites, absence of secondary metabolities does not result in immediate death, but rather in long-term impairment of the organism's...
s, both terpene
Terpene
Terpenes are a large and diverse class of organic compounds, produced by a variety of plants, particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit terpenes from their osmeterium. They are often strong smelling and thus may have had a protective...
s and alkaloid
Alkaloid
Alkaloids are a group of naturally occurring chemical compounds that contain mostly basic nitrogen atoms. This group also includes some related compounds with neutral and even weakly acidic properties. Also some synthetic compounds of similar structure are attributed to alkaloids...
s, are also derived either from ent-copalyl pyrophosphate itself or from ent-kaurene or ent-kaurenoic acid, the next two intermediates on the metabolic pathway to gibberellins. Knowledge of these secondary metabolic pathways is much less extensive that that of gibberellin biosynthesis, and is often little more than conjecture.Such conjecture is not, of course, without evidence. It can be clear from the structure of a secondary metabolite that it is almost certainly derived from ent-copalyl pyrophosphate without knowing the details of how the transformation is carried out in living plants.
It is known that ent-copalyl diphosphate synthase is produced by maize plants (Zea mays) in response to attack by Fusarium
Fusarium
Fusarium is a large genus of filamentous fungi widely distributed in soil and in association with plants. Most species are harmless saprobes, and are relatively abundant members of the soil microbial community. Some species produce mycotoxins in cereal crops that can affect human and animal health...
fungi, which suggests that it might play a role in plant defences as a precursor to phytoalexin
Phytoalexin
Phytoalexins are antimicrobial substances synthesized de novo by plants that accumulate rapidly at areas of incompatible pathogen infection. They are broad spectrum inhibitors and are chemically diverse with different types characteristic of particular plant species...
s (defensive compounds produced by the plant). Rice plants produce (at least) two different types of ent-copalyl diphosphate synthase, and only one of those participates in the production of gibberellins, suggesting again that the other is involved in the production of phytoalexins.