This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
|Superclasses:||Biosynthesis → Cofactors, Prosthetic Groups, Electron Carriers Biosynthesis → Porphyrin Compounds Biosynthesis → Chlorophyll Biosynthesis → Chlorophyllide a Biosynthesis|
Some taxa known to possess this pathway include : Allochromatium vinosum , Chlorobaculum tepidum , Rhodobacter capsulatus , Rhodobacter sphaeroides , Rhodopseudomonas palustris , Rhodospirillum rubrum , Rubrivivax gelatinosus
Expected Taxonomic Range: Bacteria
Chlorophyll is a green photosynthetic pigment found in photosynthetic plants, algae, and bacteria. Its name is derived from ancient Greek: chloros = green and phyllon = leaf. Chlorophyll absorbs mostly in the blue and, to a lesser extent, red portions of the electromagnetic spectrum, hence its intense green color. There are several variants of chlorophyll (chlorophyll a, chlorophyll a', chlorophyll b, chlorophyll c1, chlorophyll c2, and chlorophyll d). Non-oxygenic bacteria possess a related pigment called bacteriochlorophyll, which also exists in several variants (bacteriochlorophyll a, bacteriochlorophyll b, bacteriochlorophyll c, bacteriochlorophyll d, bacteriochlorophyll e and bacteriochlorophyll g). This pathway describes the formation of chlorophyllide a, an important intermediate in the biosynthesis of all chlorophylls.
About This Pathway
The biosynthetic pathway of bacteriochlorophylls begins with the condensation of eight molecules of 5-aminolevulinate to form uroporphyrinogen-III, the first cyclic tetrapyrrole compound in the pathway (see tetrapyrrole biosynthesis I (from glutamate)). This compound is then sequentially converted to protoporphyrin IX, which is the branch-point intermediate to hemes and chlorophylls.
The incorporation of Mg2+ into protoporphyrin IX occurs at the next step, resulting in the formation of Mg-protoporphyrin (MgP). A methyl transferase converts MgP into magnesium-protoporphyrin IX 13-monomethyl ester (MgPMME), which is the substrate for a cyclase reaction, which creates a fifth ring (ring E), a common feature of all chlorophylls. In anaerobic phototrophs the cyclase is a hydratase, incorporating an oxygen atom from a water molecule, by a complex process catalyzed by the cobalamin-dpendent enzyme anaerobic magnesium-protoporphyrin IX monomethyl ester cyclase. After reduction of a divinyl group to a monovinyl (or ethyl) group (a reaction that may happen at different stages along the pathway), protochlorophyllide a is finally reduced to chlorophyllide a. In this pathway, which is found in the anoxygenic phototrophs, this final reduction is carried by the enzyme light-independent protochlorophyllide reductase, permitting the organisms to synthesize bacteriochlorophyll in the dark.
This biosynthetic pathway, which occurs in all anaerobic photosynthetic organisms, has been described through genetic analysis of bacterial mutants and in vitro reconstitution of individual reactions [Suzuki97, Beale99, Ouchane04, Bollivar06].
Aerobic phototrophs possess a very similar pathway, with one exception being that the cyclase found in these organisms uses molecular oxygen as the oxygen source. A variant of the pathway found in aerobic phototrophs is described in chlorophyllide a biosynthesis III (aerobic, light independent).
Superpathways: superpathway of bacteriochlorophyll a biosynthesis
Fujita93: Fujita Y, Matsumoto H, Takahashi Y, Matsubara H (1993). "Identification of a nifDK-like gene (ORF467) involved in the biosynthesis of chlorophyll in the cyanobacterium Plectonema boryanum." Plant Cell Physiol 34(2);305-14. PMID: 8199775
Muraki10: Muraki N, Nomata J, Ebata K, Mizoguchi T, Shiba T, Tamiaki H, Kurisu G, Fujita Y (2010). "X-ray crystal structure of the light-independent protochlorophyllide reductase." Nature 465(7294);110-4. PMID: 20400946
Ouchane04: Ouchane S, Steunou AS, Picaud M, Astier C (2004). "Aerobic and anaerobic Mg-protoporphyrin monomethyl ester cyclases in purple bacteria: a strategy adopted to bypass the repressive oxygen control system." J Biol Chem 279(8);6385-94. PMID: 14617630
Armstrong89a: Armstrong GA, Alberti M, Leach F, Hearst JE (1989). "Nucleotide sequence, organization, and nature of the protein products of the carotenoid biosynthesis gene cluster of Rhodobacter capsulatus." Mol Gen Genet 216(2-3);254-68. PMID: 2747617
Bauer88a: Bauer CE, Young DA, Marrs BL (1988). "Analysis of the Rhodobacter capsulatus puf operon. Location of the oxygen-regulated promoter region and the identification of an additional puf-encoded gene." J Biol Chem 263(10);4820-7. PMID: 3127391
Block02: Block MA, Tewari AK, Albrieux C, Marechal E, Joyard J (2002). "The plant S-adenosyl-L-methionine:Mg-protoporphyrin IX methyltransferase is located in both envelope and thylakoid chloroplast membranes." Eur J Biochem 269(1);240-8. PMID: 11784318
Bollivar94: Bollivar DW, Suzuki JY, Beatty JT, Dobrowolski JM, Bauer CE (1994). "Directed mutational analysis of bacteriochlorophyll a biosynthesis in Rhodobacter capsulatus." J Mol Biol 237(5);622-40. PMID: 8158642
Bollivar94a: Bollivar DW, Jiang ZY, Bauer CE, Beale SI (1994). "Heterologous expression of the bchM gene product from Rhodobacter capsulatus and demonstration that it encodes S-adenosyl-L-methionine:Mg-protoporphyrin IX methyltransferase." J Bacteriol 176(17);5290-6. PMID: 8071204
Breckau03: Breckau D, Mahlitz E, Sauerwald A, Layer G, Jahn D (2003). "Oxygen-dependent coproporphyrinogen III oxidase (HemF) from Escherichia coli is stimulated by manganese." J Biol Chem 278(47);46625-31. PMID: 12975365
Burke93a: Burke DH, Alberti M, Hearst JE (1993). "bchFNBH bacteriochlorophyll synthesis genes of Rhodobacter capsulatus and identification of the third subunit of light-independent protochlorophyllide reductase in bacteria and plants." J Bacteriol 175(8);2414-22. PMID: 8385667
Cantoni84: Cantoni L, Dal Fiume D, Ruggieri R (1984). "Decarboxylation of uroporphyrinogen I and III in 2,3,7,8-tetrachlorodibenzo-p-dioxin induced porphyria in mice." Int J Biochem 16(5);561-5. PMID: 6724109
Choquet92: Choquet Y, Rahire M, Girard-Bascou J, Erickson J, Rochaix JD (1992). "A chloroplast gene is required for the light-independent accumulation of chlorophyll in Chlamydomonas reinhardtii." EMBO J 11(5);1697-704. PMID: 1374710
Corrigall98: Corrigall AV, Siziba KB, Maneli MH, Shephard EG, Ziman M, Dailey TA, Dailey HA, Kirsch RE, Meissner PN (1998). "Purification of and kinetic studies on a cloned protoporphyrinogen oxidase from the aerobic bacterium Bacillus subtilis." Arch Biochem Biophys 358(2);251-6. PMID: 9784236
Eisen02: Eisen JA, Nelson KE, Paulsen IT, Heidelberg JF, Wu M, Dodson RJ, Deboy R, Gwinn ML, Nelson WC, Haft DH, Hickey EK, Peterson JD, Durkin AS, Kolonay JL, Yang F, Holt I, Umayam LA, Mason T, Brenner M, Shea TP, Parksey D, Nierman WC, Feldblyum TV, Hansen CL, Craven MB, Radune D, Vamathevan J, Khouri H, White O, Gruber TM, Ketchum KA, Venter JC, Tettelin H, Bryant DA, Fraser CM (2002). "The complete genome sequence of Chlorobium tepidum TLS, a photosynthetic, anaerobic, green-sulfur bacterium." Proc Natl Acad Sci U S A 99(14);9509-14. PMID: 12093901
Gibson94: Gibson LC, Hunter CN (1994). "The bacteriochlorophyll biosynthesis gene, bchM, of Rhodobacter sphaeroides encodes S-adenosyl-L-methionine: Mg protoporphyrin IX methyltransferase." FEBS Lett 352(2);127-30. PMID: 7925960
Gibson95: Gibson LC, Willows RD, Kannangara CG, von Wettstein D, Hunter CN (1995). "Magnesium-protoporphyrin chelatase of Rhodobacter sphaeroides: reconstitution of activity by combining the products of the bchH, -I, and -D genes expressed in Escherichia coli." Proc Natl Acad Sci U S A 92(6);1941-4. PMID: 7892204
Gibson99a: Gibson LC, Jensen PE, Hunter CN (1999). "Magnesium chelatase from Rhodobacter sphaeroides: initial characterization of the enzyme using purified subunits and evidence for a BchI-BchD complex." Biochem J 337 ( Pt 2);243-51. PMID: 9882621
Gough00: Gough SP, Petersen BO, Duus JO (2000). "Anaerobic chlorophyll isocyclic ring formation in Rhodobacter capsulatus requires a cobalamin cofactor." Proc Natl Acad Sci U S A 97(12);6908-13. PMID: 10841582
Hansson92: Hansson M, Hederstedt L (1992). "Cloning and characterization of the Bacillus subtilis hemEHY gene cluster, which encodes protoheme IX biosynthetic enzymes." J Bacteriol 174(24);8081-93. PMID: 1459957
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