Metabolism of L-glyceraldehyde 3-phosphate in Escherichia coli

Abstract

When either 3H-labeled L-glyceraldehyde or 3H-labeled L-glyceraldehyde 3-phosphate (GAP) was added to cultures of Escherichia coli, the phosphoglycerides were labeled. More than 81% of the label appeared in the backbone of the phosphoglycerides. Chromatographic analyses of the labeled phosphoglycerides revealed that the label was normally distributed into phosphatidylethanolamine, phosphatidylglycerol, and cardiolipin. These results suggest that L-glyceraldehyde is phosphorylated and the resultant L-GAP is converted into sn-glycerol 3-phosphate (G3P) before being incorporated into the bacterial phosphoglycerides. Cell-free bacterial extracts catalyzed an NADPH-dependent reduction of L-GAP to sn-G3P. The partially purified enzyme was specific for L-GAP and recognized neither D-GAP nor (5,12). Intracellular L-GAP can also be formed by a glycerokinase-catalyzed phosphorylation of L-glyceraldehyde that is taken up from the growth medium (12). The mechanism by which L-GAP causes E. coli to lose viability is not known.One possibility is that L-GAP exerts its bactericidal effect by interfering with a critical biochemical reaction. In aqueous solution, L-GAP exists as an equilibrium mixture of the hydrated and free aldehyde in a molar ratio of 29:1 (14). Since the hydrated form may be considered an analog of sn-G3P, L-GAP has the potential to interfere with enzymes involved in sn-G3P metabolism. L-GAP is a competitive inhibitor of both sn-G3P acyltransferase and phosphatidylglycerol phosphate synthetase (12, 13). However, these inhibitory activities do not necessarily explain the bactericidal activity of L-GAP. The sn-G3P analogs 3-hydroxy-4-oxobutyl-1-phosphonate and 1,3,4-trihydroxybutyl-1-phosphonate are bacteriostatic rather than bactericidal, even though they also inhibit the two lipid enzymes (13; unpublished

Mirroring Perfection: The Structure of Methylglyoxal Synthase Complexed with the Competitive Inhibitor 2-Phosphoglycolate

“…This is an absolute requirement for the function of MGS, since the reverse reaction would allow MGS to form l -GAP from DHAP. l -GAP has known bactericidal activity and is known to inhibit sn -glycerol 3-phosphate acyltransferase and phosphatidylglycerol phosphate synthetase as well as fructose 1,6-bisphosphate aldolase ( − ). While the inability of MGS to abstract a proton from d -GAP is easily rationalized from the disposition of the catalytic base on the opposite side of the molecule from the C2 proton, the inability to abstract the C2 proton from l -GAP requires more explanation.…”

The diversity of microbial aldo/keto reductases from Escherichia coli K12

“…More recently, over expression of yghZ has been shown to complement ( sluggish growth) for tpiA -(triosephosphate isomerase deficient) strain of E. coli which is unable to produce dihydroxyacetone phosphate (DHAP) during growth on M9 minimal medium containing L-lactate [36]. The authors show that YghZ is able to selectively reduce L-glyceraldehyde 3-phosphate (L-GAP) to glycerol 3-phosphate (L-G3P), an activity identified previously by Tropp and coworkers [37]. The product L-G3P can be oxidised by glycerol 3-phosphate dehydrogenase to DHAP which is the route glycerol is metabolised.…”

Metabolomic Profiling Analysis of Physiological Responses to Acute Hypoxia and Reoxygenation in Juvenile Qingtian Paddy Field Carp Cyprinus Carpio Var Qingtianensis

“…In a further detection of carbohydrates, it was found that the glyceraldehyde 3-phosphate content was only significantly up-regulated under hypoxic stress in hepatopancrea; however, the other sugar detected did not markedly change during glycolysis and no activation glycolysis pathways were found. This result indicates that the glycolysis pathways is repressed as a whole, and it was detected to be significantly elevated, which may be related to the acetoacetyl-CoA produced by the metabolism of lipids ( Kalyananda et al, 1987 ). In conclusion, PF-carp will weaken the metabolism of saccharides during acute hypoxia stress and reoxygenation recovery through the gluconeogenesis pathway to obtain more energy metabolism substrates, and this process, besides providing energy during early stages of hypoxic stress, may be mainly used to maintain physiological homeostasis later in the experiment.…”