F430

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Structural formula
Structure of F430
General
Surname F430
other names
  • Coenzyme F430
  • Cofactor F430
Molecular formula C 42 H 51 N 6 NiO 13 -
External identifiers / databases
CAS number 73145-13-8
PubChem 5460020
Wikidata Q416650
properties
Molar mass 906.6 g mol −1
safety instructions
GHS hazard labeling
no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

The cofactor F430 , also F 430 , is the prosthetic group of the enzyme methyl coenzyme M reductase . It  owes its name to its absorption maximum at λ max = 430 nm. The cofactor occurs exclusively in methanogenic archaea .

discovery

F 430 was discovered in 1977 by Jean LeGall as a yellow component in cell extracts of Methanobacterium thermoautotrophicum . Because of its strong absorption at λ max  = 430 nm, it was called factor F 430 . The tetrapyrrole- like structure proposed by Thauer and co-workers in 1980 was finally verified by NMR studies.

Occurrence

Although the structure of the cofactor F430 is similar to other tetrapyrroles, it has only been detected in methanogenic archaea. In those it serves exclusively as a prosthetic group of the enzyme methyl-coenzyme-M-reductase (MCR).

Chemical properties

F 430 is reminiscent of a tetrapyrrole ring in its structure and is similar to porphyrins or corrines . The chromophore is a tetrahydro-derivative of the so-called corphins. The ring system in F 430 has a total of only five double bonds , making it the most heavily reduced tetrapyrrole ring in nature. Due to the lack of conjugated double bonds, it is yellow in contrast to the more unsaturated tetrapyrroles (for example the red heme ). In addition, the ring system is enlarged by two attached rings.

So far it is the only derivative of a tetrapyrrole system that contains a nickel ion . This is present as Ni (I) and is paramagnetic . The cofactor can be isolated by denaturing the MCR with acids. Insulated F 430 is thermally unstable and oxygen- sensitive.

Variant of cofactor F430: (17 2 S ) -17 2 -methylthio-coenzyme F430.

A variant of the cofactor F 430 was discovered, which is modified at the C17 2 atom by a methylthio group (see picture). However, this variant apparently has no effect on the nickel atom in the center, which is essential for the function of the cofactor. Why this variant is so modified is still up for discussion. Further variants and modifications have been found in other methanogenic and anaerobic methanotrophic arks.

meaning

The cofactor is the prosthetic group of the enzyme methyl coenzyme M reductase (MCR). Each enzyme contains two non- covalently bound F430s. MCR catalyzes the last step of methanogenesis , during which methane is released and a disulfide complex of coenzyme M (CoM) and coenzyme B (CoB) is formed:

The exact mechanism is not yet clear. It is also unclear whether Ni (III) can be formed as a result of the catalysis.

biosynthesis

Like all other natural tetrapyrroles, the biosynthesis of the cofactor begins with the common precursor molecule uroporphyrinogen III . This is first converted to sirohydrochlorin . The nickel atom is then incorporated into sirohydrochlorin by means of a type 2 chelatase (CfbA) so that Ni (II) sirohydrochlorin is formed. An amidase (CfbE) converts two of the acetate side chains to acetamide with consumption of ATP and N, which consequently leads to the formation of Ni (II) -sirohydrochlorin- a , c -diamide. This is reduced to an intermediate by an enzyme complex CfbC / CfbD: Ni (I) -hexahydrosirohydrochlorin- a , c -diamide. In this process, a total of six electrons and seven protons are transferred. Whether the subsequent ring closure to seco -F 430 occurs spontaneously or enzymatically is still being investigated. From seco -F 430 finally arises under ATP consumption F 430 by the carbocyclic ring F forms (with the keto group) elimination of water. This catalyzes a ligase (CfbB).

The N source necessary for biosynthesis is either glutamine or free ammonium.

Individual evidence

  1. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  2. ^ RP Gunsalus, RS Wolfe: Chromophoric factors F 342 and F 430 of Methanobacterium thermoautotrophicum. In: FEMS Microbiol. Lett. 1978, 3 (4), pp. 191-193, doi : 10.1111 / j.1574-6968.1978.tb01916.x
  3. ↑ DA Livingston et al .: To the knowledge of the factor F430 from methanogenic bacteria: Structure of the protein-free factor. In: Helv. Chim. Acta . 1984, 67 (1), pp. 334-351, doi : 10.1002 / hlca.19840670141
  4. ↑ G. Diekert et al .: Nickel requirement and factor F430 content of methanogenic bacteria. In: J Bacteriol. 1981, 148 (2), pp. 459–464, PMID 7298577 , PDF (free full-text access , English)
  5. ^ A. Ghosh et al .: Deconstructing F 430 : quantum chemical perspectives of biological methanogenesis. In: Curr Opin Chem Biol. 2001, 5 (6), pp. 744-750, PMID 11738187 .
  6. ↑ S. Mayr et al .: Structure of an F430 variant from archaea associated with anaerobic oxidation of methane. In: J. Am. Chem. Soc. 2008, 130 (32), pp. 10758-10767, PMID 18642902 , doi : 10.1021 / ja802929z .
  7. ↑ Allen, KD. et al. (2014): Discovery of multiple modified F (430) coenzymes in methanogens and anaerobic methanotrophic archaea suggests possible new roles for F (430) in nature. In: Appl Environ Microbiol. 80 (20); 6403-12. doi : 10.1128 / AEM.02202-14 ; PMID 25107965
  8. ↑ U. Ermler: On the mechanism of methyl-coenzyme M reductase. In: J. Chem. Soc., Dalton Trans. 2005, 21, pp. 345-348, PMID 16234924 , PDF (free full-text access , English)
  9. ^ SW Ragsdale: Nickel and the carbon cycle. In: J. Inorg. Biochem. 2007, 101 (11-12), pp. 1657-1666, PMID 17716738 , PMC 2100024 (free full text, PDF).
  10. ↑ Simon J. Moore, Sven T. Sowa, Christopher Schuchardt, Evelyne Deery, Andrew D. Lawrence, José Vazquez Ramos, Susan Billig, Claudia Birkemeyer, Peter T. Chivers: Elucidation of the biosynthesis of the methane catalyst coenzyme F430 . In: Nature . 543, No. 7643, March 2, 2017, ISSN  0028-0836 , pp. 78-82. doi : 10.1038 / nature21427 .
  11. ↑ Helmut Mucha, Eberhard Keller, Hans Weber, Franz Lingens, Walter Trösch: Sirohydrochlorin, a precursor of factor F430 biosynthesis in Methanobacterium thermoautotrophicum . In: FEBS Letters . 190, No. 1, October 7, 1985, pp. 169-171. doi : 10.1016 / 0014-5793 (85) 80451-8 .
  12. ↑ Zheng K, Ngo PD, Owens VL, Yang XP, Mansoorabadi SO: The biosynthetic pathway of coenzyme F430 in methanogenic and methanotrophic archaea . In: Science . 354, No. 6310, October 2016, pp. 339–342. doi : 10.1126 / science.aag2947 . PMID 27846569 .

literature

  • AA DiMarco et al .: Unusual coenzymes of methanogenesis. In: Annu Rev Biochem . 59 (1990), pp. 355-394, PMID 2115763 .
  • RP Hausinger: Nickel utilization by microorganisms. In: Microbiol Rev. 51, (1) 1987, pp. 22-42, PMID 3104749 , PDF (free full-text access , English)

See also