Cofactor F430 Explained

Cofactor F430 should not be confused with Coenzyme F420.

F430 is the cofactor (sometimes called the coenzyme) of the enzyme methyl coenzyme M reductase (MCR).[1] [2] MCR catalyzes the reaction that releases methane in the final step of methanogenesis:

+ HS–CoB → + CoB–S–S–CoM

It is found only in methanogenic Archaea[3] and anaerobic methanotrophic Archaea. It occurs in relatively high concentrations in archaea that are involved in reverse methanogenesis: these can contain up to 7% by weight of the nickel protein.[4]

Structure

The trivial name cofactor F430 was assigned in 1978 based on the properties of a yellow sample extracted from Methanobacterium thermoautotrophicum, which had a spectroscopic maximum at 430 nm.[5] It was identified as the MCR cofactor in 1982[6] and the complete structure was deduced by X-ray crystallography and NMR spectroscopy.[7] Coenzyme F430 features a reduced porphyrin in a macrocyclic ring system called a corphin.[8] In addition, it possesses two additional rings in comparison to the standard tetrapyrrole (rings A-D), having a γ-lactam ring E and a keto-containing carbocyclic ring F. It is the only natural tetrapyrrole containing nickel, an element rarely found in biological systems.[9]

Biosynthesis

The biosynthesis builds from uroporphyrinogen III, the progenitor of all natural tetrapyrroles, including chlorophyll, vitamin B12, phycobilins, siroheme, heme, and heme d1. It is converted to sirohydrochlorin via dihydrosirohydrochlorin.[10] Insertion of nickel into this tetrapyrrole is catalysed in reaction by the same chelatase, CbiX, which inserts cobalt in the biosynthesis of cobalamin, here giving nickel(II)-sirohydrochlorin.[11] The ATP-dependent Ni-sirohydrochlorin a,c-diamide synthase (CfbE) then converts the a and c acetate side chains to acetamide in reactions, generating nickel(II)-sirohydrochlorin a,c-diamide. The sequence of the two amidations is random.[11] A two-component complex Ni-sirohydrochlorin a,c-diamide reductive cyclase (CfbCD) carries out a 6-electron and 7-proton reduction of the ring system in a reaction generating the 15,173-seco-F430-173-acid (seco-F430) intermediate. Reduction involves ATP hydrolysis and electrons are relayed through two 4Fe-4S centres. In the final step, the keto-containing carbocyclic ring F is formed by an ATP-dependent enzyme Coenzyme F(430) synthetase (CfbB) in reaction, generating coenzyme F430.[11] [12] [13] This enzyme is a MurF-like ligase, as found in peptidoglycan biosynthesis.

Notes and References

  1. Book: Ragdale . Stephen W. . Biochemistry of Methyl-Coenzyme M Reductase: The Nickel Metalloenzyme that Catalyzes the Final Step in Synthesis and the First Step in Anaerobic Oxidation of the Greenhouse Gas Methane . Peter M.H. Kroneck and Martha E. Sosa Torres . The Metal-Driven Biogeochemistry of Gaseous Compounds in the Environment . Metal Ions in Life Sciences . 14 . 2014 . Springer . 125–145 . 10.1007/978-94-017-9269-1_6 . 25416393 . 978-94-017-9268-4 .
  2. 10.1038/nrmicro.2016.170 . Masters of methane . 2016 . Hofer . Ursula . Nature Reviews Microbiology . 14 . 12 . 727 . 27818502 . 35175663 . free .
  3. 10.1099/00221287-144-9-2377 . Thauer RK . Biochemistry of Methanogenesis: a Tribute to Marjory Stephenson . Microbiology . 1998 . 144 . 9 . 2377–2406 . 9782487 . free .
  4. Krüger M, Meyerdierks A, Glöckner FO . A conspicuous nickel protein in microbial mats that oxidize methane anaerobically . Nature . 426 . 6968 . 878–81 . December 2003 . 14685246 . 10.1038/nature02207 . etal. 2003Natur.426..878K . 4383740 .
  5. 10.1111/j.1574-6968.1978.tb01916.x . Chromophoric factors F342 and F430 of Methanobacterium thermoautotrophicum . 1978 . Gunsalus . R.P. . Wolfe . R.S. . FEMS Microbiology Letters . 3 . 4 . 191–193 . free .
  6. 10.1073/pnas.79.12.3707 . Nickel-containing factor F430: Chromophore of the methylreductase of Methanobacterium . 1982 . Ellefson . W. L. . Whitman . W. B. . Wolfe . R. S. . Proceedings of the National Academy of Sciences . 79 . 12 . 3707–3710 . 6954513 . 346495 . 1982PNAS...79.3707E . free .
  7. Färber G, Keller W, Kratky C, Jaun B, Pfaltz A, Spinner C, Kobelt A, Eschenmoser A . Coenzyme F430 from Methanogenic Bacteria : Complete Assignment of Configuration Based on an X-ray Analysis of 12,13-diepi-F430 Pentamethyl Ester and on NMR Spectroscopy . Helvetica Chimica Acta . 74 . 4 . 697–716 . 1991 . 10.1002/hlca.19910740404.
  8. 10.1111/j.1749-6632.1986.tb48030.x . 1986 . 471 . 1 International . Eschenmoser . A. . Chemistry of Corphinoids . Annals of the New York Academy of Sciences . 108–129 . 1986NYASA.471..108E . 83719424 .
  9. Book: 9781119159834 . Metalloprotein Active Site Assembly . Johnson . Michael K. . Scott . Robert A. . 2 October 2017 . Wiley .
  10. Mucha. Helmut. Keller. Eberhard. Weber. Hans. Lingens. Franz. Trösch. Walter. 1985-10-07. Sirohydrochlorin, a precursor of factor F430 biosynthesis in Methanobacterium thermoautotrophicum. FEBS Letters. 190. 1. 169–171. 10.1016/0014-5793(85)80451-8. free.
  11. 10.1038/nature21427 . 2017 . 543 . 7643 . Moore . Simon J. . Sowa . Sven T. . Schuchardt . Christopher . Deery . Evelyne . Lawrence . Andrew D. . Ramos . José Vazquez . Billig . Susan . Birkemeyer . Claudia . Chivers . Peter T. . Howard . Mark J. . Rigby . Stephen E. J. . Layer . Gunhild . Warren . Martin J. . Elucidation of the biosynthesis of the methane catalyst coenzyme F430 . Nature . 78–82 . 28225763 . 5337119 . 2017Natur.543...78M .
  12. 10.1126/science.aag2947 . free . The biosynthetic pathway of coenzyme F430 in methanogenic and methanotrophic archaea . 2016 . Zheng . Kaiyuan . Ngo . Phong D. . Owens . Victoria L. . Yang . Xue-Peng . Mansoorabadi . Steven O. . Science . 354 . 6310 . 339–342 . 27846569 . 2016Sci...354..339Z .
  13. Web site: Pathway: factor 430 biosynthesis . R. Caspi . MetaCyc Metabolic Pathway Database . 2017-01-09 . 2020-04-27 .

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