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.
Synonyms: methylthiopropionate biosynthesis
|Superclasses:||Biosynthesis → Secondary Metabolites Biosynthesis → Sulfur-Containing Secondary Compounds Biosynthesis|
3-Methylthiopropanoate is produced by several routes: (i) catabolism of methionine [Steele79], (ii) demethylation of dimethylsulfoniopropionate in bacteria [vanderMaarel96] or (iii) a shunt route of the 3-methylthiopropanoate biosynthesis.
In the latter route, represented here, 1,2-dihydroxy-3-keto-5-methylthiopentene is oxidized to formate and 3-methylthioproprionate. The purpose of this shunt route, also known as the off-pathway reaction of methionine salvage, is yet unknown; it has been postulated that it might provide a mechanism for regulating methionine levels in vivo [Dai01].
The enzyme responsible for the formation of 3-(methylthio)propanoate is acireductone dioxygenase. This enzyme has been found in a number of species and has been shown to be involved in the catalysis of two reactions: the Fe2+-dependent conversion of 1,2-dihydroxy-5-(methylthio)pent-1-en-3-one into 2-oxo-4-methylthiobutanoate (EC 188.8.131.52) and the Ni2+-dependent conversion of the same substrate into 3-(methylthio)propanoate (EC 184.108.40.206) [Ju06]. This enzyme has been characterized for Klebsiella pneumoniae (see acireductone dioxygenase) and in rice. The latter was shown to catalyze mostly the Fe2+-acireductone dioxygenase step. Indeed, this enzyme appears to have a preference for Fe2+ rather than Ni2+ suggesting it might be involved mostly in the S-methyl-5-thio-α-D-ribose 1-phosphate degradation rather than the shunt pathway producing the cytotoxic compound 3-S-methylthiopropionate [Sauter05].
This Pathway in Plants:
In plants, the production of 3-methylthiopropionate remains uncertain. The compound is cytotoxic to plant cells and has been reported in leaves of cassava infected by Xanthomonas campestris as a blight-inducing toxin [Perreaux86]. It is known to be produced by phytopathogens and by soil microorganisms, and to affect the growth of plant seedlings [Kim03d].
Ju06: Ju T, Goldsmith RB, Chai SC, Maroney MJ, Pochapsky SS, Pochapsky TC (2006). "One protein, two enzymes revisited: a structural entropy switch interconverts the two isoforms of acireductone dioxygenase." J Mol Biol 363(4);823-34. PMID: 16989860
Kim03d: Kim YC, Kim HJ, Park KH, Cho JY, Kim KY, Cho BH (2003). "3-methylthiopropanoic acid produced by Enterobacter intermedium 60-2G inhibits fungal growth and weed seedling development." J Antibiot (Tokyo) 56(2);177-80. PMID: 12715879
Perreaux86: Perreaux D., Maraite H., Meyer J.A. (1986). "Detection of 3-methylthio propionic acid in cassava leaves infected by Xanthomonas campestris pv. manihotis." Physiological and molecular plant pathology.
Pochapsky02: Pochapsky TC, Pochapsky SS, Ju T, Mo H, Al-Mjeni F, Maroney MJ (2002). "Modeling and experiment yields the structure of acireductone dioxygenase from Klebsiella pneumoniae." Nat Struct Biol 9(12);966-72. PMID: 12402029
Sauter05: Sauter M, Lorbiecke R, Ouyang B, Pochapsky TC, Rzewuski G (2005). "The immediate-early ethylene response gene OsARD1 encodes an acireductone dioxygenase involved in recycling of the ethylene precursor S-adenosylmethionine." Plant J 44(5);718-29. PMID: 16297065
vanderMaarel96: van der Maarel MJ, Jansen M, Haanstra R, Meijer WG, Hansen TA (1996). "Demethylation of dimethylsulfoniopropionate to 3-S-methylmercaptopropionate by marine sulfate-reducing bacteria." Appl Environ Microbiol 62(11);3978-84. PMID: 8899985
Ashida03: Ashida H, Saito Y, Kojima C, Kobayashi K, Ogasawara N, Yokota A (2003). "A functional link between RuBisCO-like protein of Bacillus and photosynthetic RuBisCO." Science 302(5643);286-90. PMID: 14551435
Howard06: Howard EC, Henriksen JR, Buchan A, Reisch CR, Burgmann H, Welsh R, Ye W, Gonzalez JM, Mace K, Joye SB, Kiene RP, Whitman WB, Moran MA (2006). "Bacterial taxa that limit sulfur flux from the ocean." Science 314(5799);649-52. PMID: 17068264
Wray95: Wray JW, Abeles RH (1995). "The methionine salvage pathway in Klebsiella pneumoniae and rat liver. Identification and characterization of two novel dioxygenases." J Biol Chem 1995;270(7);3147-53. PMID: 7852397
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