Subsystem: Methylglyoxal Metabolism
This subsystem's description is:
Methylglyoxal is an electrophile, which at high concentrations can cause cell death. Methylglyoxal reacts rapidly with both proteins and nucleic acids and thus is both toxic and mutagenic. It is a natural metabolite that is related to intermediates in the glycolytic sequence, e.g. dihydroxyacetone phosphate, and its detoxification leads to the production of D-lactate.
The main source of methylglyoxal is the nonenzymatic fragmentation of triose phosphates, but it also is formed during threonine catabolism and acetone oxidation. In some prokaryotes, dihydroxyacetone phosphate is enzymatically converted to methylglyoxal and inorganic phosphate by methylglyoxal synthase (EC 18.104.22.168) in response to phosphate starvation.
The production of methylglyoxal by cells is a paradox that can be resolved by assigning an important role in adaptation to conditions of nutrient imbalance. Analysis of a methylglyoxal synthase-deficient mutant provides evidence that methylglyoxal production is required to allow growth under certain environmental conditions. The production of methylglyoxal may represent a high-risk strategy that facilitates adaptation, but which on failure leads to cell death.
Prevention of methylglyoxal accumulation can be controlled at the level of detoxification. Several methylglyoxal detoxification pathways have been identified.
In enteric bacteria, three detoxification routes have been identified:
(1) the glutathione-dependent glyoxalase I-II system,
(2) glutathione-independent glyoxalase III, and
(3) methylglyoxal reductases and dehydrogenases.
The major detoxification system in Escherichia coli, the glutathione-dependent glyoxalase I-II system, is conserved from bacteria to man, and this implies universal exposure to this compound at some stage of all life cycles.
1.0 - Methylglyoxal formation(mgs) + Main (Glyoxalase I-II) detoxification pathway are present;
2.0 – Methylglyoxal formation(mgs) + Alternate detoxification routes;
3.0 - Methylglyoxal formation(mgs) + Main and alternate detoxification routes;
4.0 - Just Main (Glyoxalase I-II) detoxification pathway (No mgs gene -non-enzymatic formation of methylglyoxal);
5.0 - Just Alternate detoxification routes ( No mgs gene);
6.0 - No formation, but both - Main and alternate- detoxification routes are present;
9.0 - Just Methylglyoxal formation(mgs gene), no detoxification routes found.
For more information, please check out the description and the additional notes tabs, below
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