Metabolic flux analysis for succinic acid production by recombinantEscherichia coli with amplified malic enzyme activity

2001 ◽  
Vol 74 (2) ◽  
pp. 89-95 ◽  
Author(s):  
Soon Ho Hong ◽  
Sang Yup Lee
Keyword(s):  
Enzyme Activity ◽  
Succinic Acid ◽  
Metabolic Flux Analysis ◽  
Malic Enzyme ◽  
Acid Production ◽  
Metabolic Flux ◽  
Flux Analysis ◽  
Succinic Acid Production ◽  
Malic Enzyme Activity

Metabolic flux analysis on succinic acid production from crude glycerol by Actinobacillus succinogenes

2021 ◽  
Author(s):  
Omjit Sillaparassamee ◽  
Sopa Chinwetkitvanich ◽  
Suwimon Kanchanasuta ◽  
Nipon Pisutpaisal ◽  
Verawat Champreda
Keyword(s):  
Succinic Acid ◽  
Metabolic Flux Analysis ◽  
Acid Production ◽  
Crude Glycerol ◽  
Metabolic Flux ◽  
Flux Analysis ◽  
Actinobacillus Succinogenes ◽  
Succinic Acid Production

scholarly journals YtsJ Has the Major Physiological Role of the Four Paralogous Malic Enzyme Isoforms in Bacillus subtilis

2006 ◽  
Vol 188 (13) ◽  
pp. 4727-4736 ◽  
Author(s):  
Guillaume Lerondel ◽  
Thierry Doan ◽  
Nicola Zamboni ◽  
Uwe Sauer ◽  
Stéphane Aymerich
Keyword(s):  
Enzyme Activity ◽  
Bacillus Subtilis ◽  
Malic Enzyme ◽  
Metabolic Flux ◽  
Physiological Role ◽  
Extreme Case ◽  
Growth Defect ◽  
Flux Analysis ◽  
Malic Enzyme Activity

ABSTRACT The Bacillus subtilis genome contains several sets of paralogs. An extreme case is the four putative malic enzyme genes maeA, malS, ytsJ, and mleA. maeA was demonstrated to encode malic enzyme activity, to be inducible by malate, but also to be dispensable for growth on malate. We report systematic experiments to test whether these four genes ensure backup or cover different functions. Analysis of single- and multiple-mutant strains demonstrated that ytsJ has a major physiological role in malate utilization for which none of the other three genes could compensate. In contrast, maeA, malS, and mleA had distinct roles in malate utilization for which they could compensate one another. The four proteins exhibited malic enzyme activity; MalS, MleA, and MaeA exhibited 4- to 90-fold higher activities with NAD+ than with NADP+. YtsJ activity, in contrast, was 70-fold higher with NADP+ than with NAD+, with Km values of 0.055 and 2.8 mM, respectively. lacZ fusions revealed strong transcription of ytsJ, twofold higher in malate than in glucose medium, but weak transcription of malS and mleA. In contrast, mleA was strongly transcribed in complex medium. Metabolic flux analysis confirmed the major role of YtsJ in malate-to-pyruvate interconversion. While overexpression of the NADP-dependent Escherichia coli malic enzyme MaeB did not suppress the growth defect of a ytsJ mutant on malate, overexpression of the transhydrogenase UdhA from E. coli partially suppressed it. These results suggest an additional physiological role of YtsJ beyond that of malate-to-pyruvate conversion.

scholarly journals 13C metabolic flux analysis on roles of malate transporter in lipid accumulation of Mucor circinelloides

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
Lu Wang ◽  
Huaiyuan Zhang ◽  
Yao Zhang ◽  
Yuanda Song
Keyword(s):  
Fatty Acid ◽  
Metabolic Flux Analysis ◽  
Lipid Accumulation ◽  
Malic Enzyme ◽  
Metabolic Flux ◽  
Flux Ratio ◽  
Tca Cycle ◽  
Flux Analysis ◽  
Control Strain ◽  
Malate Transporter

Abstract Background Mitochondrial and cytoplasmic malate transporter proteins are responsible for transmembrane transport of malate, thereby linking malate metabolism in various subcellular regions of the cell. These transporters play an important role in fatty acid biosynthesis of oleaginous microorganisms. Our previous studies have found that lipid content of the recombinant Mucor circinelloides (M. circinelloides) strain with mitochondrial malate transporter (mt) gene overexpression was increased by 70%, while that of strain with mt gene knockout was decreased by 27%. However, the mechanism of malate transporter promoting the transport of mitochondrial malate and citrate related to lipid accumulation is not clear. Therefore, 13C-labeled glucose metabolic flux analysis was carried out to identify the metabolic network topology and estimate intracellular fluxes of genetically engineered M. circinelloides strains for the purpose of better understanding the roles of malate transporters in citrate transport systems and lipid accumulation. Results The metabolic flux distribution analysis suggested that tricarboxylic acid (TCA) cycle flux ratio of mt-overexpression strains was decreased compared to that of the control strain, but in contrast, glyoxylic acid (GOX) cycle flux ratio was increased. Accordingly, the mt-knockout strain showed an opposite phenomenon with a higher TCA cycle flux ratio and a lower GOX cycle flux ratio than the control strain. GOX cycle might be more effective than TCA cycle in producing malate and oxaloacetate replenishment. Moreover, a relatively higher flux ratio of the pentose phosphate (PP) pathway was obtained in mt-overexpression strains, but no significant difference in the malic enzyme flux between recombinant strains and the control strain. Our results confirmed that PP pathway might play an important role for supplying NADPH and malic enzyme is not a limiting factor for fatty acid synthesis in oleaginous fungus M. circinelloides strains. Conclusion Intracellular metabolic flux information suggested that mt-overexpression strains had higher flux in PP pathway and GOX cycle, lower flux in TCA cycle, and no difference in malic enzyme cycle. Together, the role of malate transporter was assumed to further participate in transporting cycle of acetyl-CoA and drive PP pathway to supply NADPH required for lipid accumulation in recombinant M. circinelloides strains.

Morphological and biochemical analyses of changes in rat hepatocytes related to wine and ethanol consumption

1984 ◽  
Vol 42 ◽  
pp. 232-233
Author(s):  
S.M. Geyer ◽  
C.L. Mendenhall ◽  
J.T. Hung ◽  
E.L. Cardell ◽  
R.L. Drake ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Enzyme Activity ◽  
Malic Enzyme ◽  
Smooth Endoplasmic Reticulum ◽  
Rat Hepatocytes ◽  
Mature Male ◽  
Treatment Groups ◽  
Malic Enzyme Activity ◽  
Biochemical Analyses

Thirty-three mature male Holtzman rats were randomly placed in 3 treatment groups: Controls (C); Ethanolics (E); and Wine drinkers (W). The animals were fed synthetic diets (Lieber type) with ethanol or wine substituted isocalorically for carbohydrates in the diet of E and W groups, respectively. W received a volume of wine which provided the same gram quantity of alcohol consumed by E. The animals were sacrificed by decapitation after 6 weeks and the livers processed for quantitative triglycerides (T3), proteins, malic enzyme activity (MEA), light microscopy (LM) and electron microscopy (EM). Morphometric analysis of randomly selected LM and EM micrographs was performed to determine organellar changes in centrilobular (CV) and periportal (PV) regions of the liver. This analysis (Table 1) showed that hepatocytes from E were larger than those in C and W groups. Smooth endoplasmic reticulum decreased in E and increased in W compared to C values.

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