Browsing Pathways

D-allose can be used as source of carbon for E.coli. D-allose is imported into E.coli by D-allose ABC transporter without phosphorylation. Allose-6-phosphate isomerase and allulose-6-phosphate 3-epimerase catalyze the remaining reactions resulting in D-allulose 6 phosphate and Beta-D-fructofuranose 6-phosphate respectively. Once Beta D fructofuranose 6-phosphate is synthesized, it can be used in the glycolysis and pyruvatedehydrogenase pathway.

Cardiolipin (CL) is an important component of the inner mitochondrial membrane where it constitutes about 20% of the total lipid composition. It is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism (Wikipedia). Cardiolipin biosynthesis occurs mainly in the mitochondria, but there also exists an alternative synthesis route for CDP-diacylglycerol that takes place in the endoplasmic reticulum. This second route may supplement this pathway. All membrane-localized enzymes are coloured dark green in the image. First, dihydroxyacetone phosphate (or glycerone phosphate) from glycolysis is used by the cytosolic enzyme glycerol-3-phosphate dehydrogenase [NAD(+)] to synthesize sn-glycerol 3-phosphate. Second, the mitochondrial outer membrane enzyme glycerol-3-phosphate acyltransferase esterifies an acyl-group to the sn-1 position of sn-glycerol 3-phosphate to form 1-acyl-sn-glycerol 3-phosphate (lysophosphatidic acid or LPA). Third, the enzyme 1-acyl-sn-glycerol-3-phosphate acyltransferase converts LPA into phosphatidic acid (PA or 1,2-diacyl-sn-glycerol 3-phosphate) by esterifying an acyl-group to the sn-2 position of the glycerol backbone. PA is then transferred to the inner mitochondrial membrane to continue cardiolipin synthesis. Fourth, magnesium-dependent phosphatidate cytidylyltransferase catalyzes the conversion of PA into CDP-diacylglycerol. Fifth, CDP-diacylglycerol--glycerol-3-phosphate 3-phosphatidyltransferase synthesizes phosphatidylglycerophosphate (PGP). Sixth, phosphatidylglycerophosphatase and protein-tyrosine phosphatase dephosphorylates PGP to form phosphatidylglycerol (PG). Last, cardiolipin synthase catalyzes the synthesis of cardiolipin by transferring a phosphatidyl group from a second CDP-diacylglycerol to PG. It requires a divalent metal cation cofactor.

Cardiolipin (CL) is an important component of the inner mitochondrial membrane where it constitutes about 20% of the total lipid composition. It is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism (Wikipedia). Cardiolipin biosynthesis occurs mainly in the mitochondria, but there also exists an alternative synthesis route for CDP-diacylglycerol that takes place in the endoplasmic reticulum. This second route may supplement this pathway. All membrane-localized enzymes are coloured dark green in the image. First, dihydroxyacetone phosphate (or glycerone phosphate) from glycolysis is used by the cytosolic enzyme glycerol-3-phosphate dehydrogenase [NAD(+)] to synthesize sn-glycerol 3-phosphate. Second, the mitochondrial outer membrane enzyme glycerol-3-phosphate acyltransferase esterifies an acyl-group to the sn-1 position of sn-glycerol 3-phosphate to form 1-acyl-sn-glycerol 3-phosphate (lysophosphatidic acid or LPA). Third, the enzyme 1-acyl-sn-glycerol-3-phosphate acyltransferase converts LPA into phosphatidic acid (PA or 1,2-diacyl-sn-glycerol 3-phosphate) by esterifying an acyl-group to the sn-2 position of the glycerol backbone. PA is then transferred to the inner mitochondrial membrane to continue cardiolipin synthesis. Fourth, magnesium-dependent phosphatidate cytidylyltransferase catalyzes the conversion of PA into CDP-diacylglycerol. Fifth, CDP-diacylglycerol--glycerol-3-phosphate 3-phosphatidyltransferase synthesizes phosphatidylglycerophosphate (PGP). Sixth, phosphatidylglycerophosphatase and protein-tyrosine phosphatase dephosphorylates PGP to form phosphatidylglycerol (PG). Last, cardiolipin synthase catalyzes the synthesis of cardiolipin by transferring a phosphatidyl group from a second CDP-diacylglycerol to PG. It requires a divalent metal cation cofactor.

Escherichia coli can solely use D-galactonate as a carbon and energy source. The initial step, after the transport of galactonic acid into the cell is the dehydration of D-galactonate to 2-dehydro-3-deoxy-D-galactonate by D-galactonate dehydratase. Subsequent phosphorylation by 2-dehydro-3-deoxygalactonate kinase and aldol cleavage by 2-oxo-3-deoxygalactonate 6-phosphate aldolase produces pyruvate and D-glyceraldehyde-3-phosphate, which enter central metabolism. Galactitol can also be utilized by E. coli K-12 as the sole source of carbon and energy. Each enters the cell via a specific phosphotransferase system, so the first intracellular species is D-galactitol-1-phosphate or D-galactitol-6-phosphate, which are identical. This sugar alcohol phosphate becomes the substrate for a dehydrogenase that oxidizes its 2-alcohol group to a keto group. Galactitol-1-phosphate is dehydrogenated to tagatose-6-phosphate which is then acted on by a kinase and an aldose and eventually is converted to glycolysis intermediates.

The biosynthesis of glutathione starts with the introduction of L-glutamic acid through either a glutamate:sodium symporter, glutamate / aspartate : H+ symporter GltP or a glutamate / aspartate ABC transporter. Once in the cytoplasm, L-glutamice acid reacts with L-cysteine through an ATP glutamate-cysteine ligase resulting in gamma-glutamylcysteine. This compound reacts which Glycine through an ATP driven glutathione synthetase thus catabolizing Glutathione. This compound is metabolized through a spontaneous reaction with an oxidized glutaredoxin resulting in a reduced glutaredoxin and an oxidized glutathione. This compound is reduced by a NADPH glutathione reductase resulting in a glutathione. Glutathione can then be degraded into various different glutathione containing compounds by reacting with a napthalene or Bromobenzene-2,3-oxide through a glutathione S-transferase.

Cardiolipin (CL) is an important component of the inner mitochondrial membrane where it constitutes about 20% of the total lipid composition. It is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism (Wikipedia). Cardiolipin biosynthesis occurs mainly in the mitochondria, but there also exists an alternative synthesis route for CDP-diacylglycerol that takes place in the endoplasmic reticulum. This second route may supplement this pathway. All membrane-localized enzymes are coloured dark green in the image. First, dihydroxyacetone phosphate (or glycerone phosphate) from glycolysis is used by the cytosolic enzyme glycerol-3-phosphate dehydrogenase [NAD(+)] to synthesize sn-glycerol 3-phosphate. Second, the mitochondrial outer membrane enzyme glycerol-3-phosphate acyltransferase esterifies an acyl-group to the sn-1 position of sn-glycerol 3-phosphate to form 1-acyl-sn-glycerol 3-phosphate (lysophosphatidic acid or LPA). Third, the enzyme 1-acyl-sn-glycerol-3-phosphate acyltransferase converts LPA into phosphatidic acid (PA or 1,2-diacyl-sn-glycerol 3-phosphate) by esterifying an acyl-group to the sn-2 position of the glycerol backbone. PA is then transferred to the inner mitochondrial membrane to continue cardiolipin synthesis. Fourth, magnesium-dependent phosphatidate cytidylyltransferase catalyzes the conversion of PA into CDP-diacylglycerol. Fifth, CDP-diacylglycerol--glycerol-3-phosphate 3-phosphatidyltransferase synthesizes phosphatidylglycerophosphate (PGP). Sixth, phosphatidylglycerophosphatase and protein-tyrosine phosphatase dephosphorylates PGP to form phosphatidylglycerol (PG). Last, cardiolipin synthase catalyzes the synthesis of cardiolipin by transferring a phosphatidyl group from a second CDP-diacylglycerol to PG. It requires a divalent metal cation cofactor.

Cardiolipin (CL) is an important component of the inner mitochondrial membrane where it constitutes about 20% of the total lipid composition. It is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism (Wikipedia). Cardiolipin biosynthesis occurs mainly in the mitochondria, but there also exists an alternative synthesis route for CDP-diacylglycerol that takes place in the endoplasmic reticulum. This second route may supplement this pathway. All membrane-localized enzymes are coloured dark green in the image. First, dihydroxyacetone phosphate (or glycerone phosphate) from glycolysis is used by the cytosolic enzyme glycerol-3-phosphate dehydrogenase [NAD(+)] to synthesize sn-glycerol 3-phosphate. Second, the mitochondrial outer membrane enzyme glycerol-3-phosphate acyltransferase esterifies an acyl-group to the sn-1 position of sn-glycerol 3-phosphate to form 1-acyl-sn-glycerol 3-phosphate (lysophosphatidic acid or LPA). Third, the enzyme 1-acyl-sn-glycerol-3-phosphate acyltransferase converts LPA into phosphatidic acid (PA or 1,2-diacyl-sn-glycerol 3-phosphate) by esterifying an acyl-group to the sn-2 position of the glycerol backbone. PA is then transferred to the inner mitochondrial membrane to continue cardiolipin synthesis. Fourth, magnesium-dependent phosphatidate cytidylyltransferase catalyzes the conversion of PA into CDP-diacylglycerol. Fifth, CDP-diacylglycerol--glycerol-3-phosphate 3-phosphatidyltransferase synthesizes phosphatidylglycerophosphate (PGP). Sixth, phosphatidylglycerophosphatase and protein-tyrosine phosphatase dephosphorylates PGP to form phosphatidylglycerol (PG). Last, cardiolipin synthase catalyzes the synthesis of cardiolipin by transferring a phosphatidyl group from a second CDP-diacylglycerol to PG. It requires a divalent metal cation cofactor.

Escherichia coli can solely use D-galactonate as a carbon and energy source. The initial step, after the transport of galactonic acid into the cell is the dehydration of D-galactonate to 2-dehydro-3-deoxy-D-galactonate by D-galactonate dehydratase. Subsequent phosphorylation by 2-dehydro-3-deoxygalactonate kinase and aldol cleavage by 2-oxo-3-deoxygalactonate 6-phosphate aldolase produces pyruvate and D-glyceraldehyde-3-phosphate, which enter central metabolism. Galactitol can also be utilized by E. coli K-12 as the sole source of carbon and energy. Each enters the cell via a specific phosphotransferase system, so the first intracellular species is D-galactitol-1-phosphate or D-galactitol-6-phosphate, which are identical. This sugar alcohol phosphate becomes the substrate for a dehydrogenase that oxidizes its 2-alcohol group to a keto group. Galactitol-1-phosphate is dehydrogenated to tagatose-6-phosphate which is then acted on by a kinase and an aldose and eventually is converted to glycolysis intermediates.

NAD molecules have a relatively short half-life. NAD can be degraded by enzymes, and the degraded NAD molecule can be recouped by NAD salvage cycles. NAD salvage cycles can be used for recycling degraded NAD products such as nicotinamide and nicotinamide D-ribonucleotide. NAD salvage cycles can also be used for absorption of exogenous NAD+. NAD reacts spontaneously with water resulting in the release of hydrogen ion, AMP and beta-nicotinamide D-ribonucleotide. This enzyme can either interact spontaneously with water resulting in the release of D-ribofuranose 5-phosphate, hydrogen ion and Nacinamide. On the other hand beta-nicotinamide D-ribonucleotide can also react with water through NMN amidohydrolase resulting in ammonium, and Nicotinate beta-D-ribonucleotide. Also it can interact with water spontaneously resulting in the release of phosphate resulting in a Nicotinamide riboside. Niacinamide interacts with water through a nicotinamidase resulting in a release of ammonium and nicotinic acid. Nicotinic acid interacts with water and phosphoribosyl pyrophosphate through an ATP driven nicotinate phosphoribosyltransferase resulting in the release of ADP, pyrophosphate and phosphate and nicotinate beta-D-ribonucleotide. Nicotinamide riboside interacts with an ATP driven NadR DNA-binding transcriptional repressor and NMN adenylyltransferase (Escherichia coli) resulting in a ADP, hydrogen ion and beta-nicotinamide D-ribonucleotide. The latter interacts with ATP and hydrogen ions through NadR DNA-binding transcriptional repressor and NMN adenylyltransferase resulting in pyrophosphate and NAD. Nicotinate beta-D-ribonucleotide is adenylated through the interaction with ATP and a hydrogen ion through a nicotinate-mononucleotide adenylyltransferase resulting in pyrophosphate and Nicotinic acid adenine dinucleotide. Nicotinic acid adenine dinucleotide interacts with L-glutamine and water through an ATP driven NAD synthease, NH3-dependent resulting in AMP, pyrophosphate, hydrogen ion, L-glutamic acid and NAD.

The biosynthesis of glutathione starts with the introduction of L-glutamic acid through either a glutamate:sodium symporter, glutamate / aspartate : H+ symporter GltP or a glutamate / aspartate ABC transporter. Once in the cytoplasm, L-glutamice acid reacts with L-cysteine through an ATP glutamate-cysteine ligase resulting in gamma-glutamylcysteine. This compound reacts which Glycine through an ATP driven glutathione synthetase thus catabolizing Glutathione. This compound is metabolized through a spontaneous reaction with an oxidized glutaredoxin resulting in a reduced glutaredoxin and an oxidized glutathione. This compound is reduced by a NADPH glutathione reductase resulting in a glutathione. Glutathione can then be degraded into various different glutathione containing compounds by reacting with a napthalene or Bromobenzene-2,3-oxide through a glutathione S-transferase.