Browsing Pathways

Phospholipids are membrane components in E. coli. The major phospholipids of E. coli are phosphatidylethanolamine, phosphatidylglycerol and cardiolipin. All phospholipids contain sn-glycerol-3-phosphate esterified with fatty acids at the sn-1 and sn-2 positions. The reaction starts from a glycerone phosphate (dihydroxyacetone phosphate) produced in glycolysis. The glycerone phosphate is transformed to a sn-glycerol 3-phosphate (glycerol 3 phosphate) by NADPH driven glycerol-3-phosphate dehydrogenase. Sn-glycerol 3-phosphate is transformed to a 1-acyl-sn-glycerol 3-phosphate(1-oleyl-2-lyso-phosphatidate , 1-palmitoylglycerol 3-phosphate , 1-stearoyl-sn-glycerol 3-phosphate). This can be achieve by a sn-glycerol-3-phosphate 1-0-acyltransferase that interacts either with a long-chain acyl-CoA or with an acyl-[acp]. The 1-acyl-sn-glycerol 3-phosphate is transformed into a 1,2-diacyl-sn-glycerol 3-phosphate through a 1-acylglycerol-3-phosphate O-acyltransferase. This compound is then converted into a CPD-diacylglycerol through a CTP (phosphatidate cytididyltransferase. CPD-diacylglycerol can be transformed either to a L-1-phosphatidylserine or a L-1-phosphatidylglycerol-phosphate through a phosphatidylserine synthase or a phosphatidylglycerophosphate synthase respectively. The L-1-phosphatidylserine transforms into L-1-phosphatidylethanolamine through a phosphatidylserine decarboxylase, o the other hand L-1-phosphatidylglycerol-phosphate gets transformed into a L-1-phosphatidyl-glycerol through a phosphatidylglycerophosphatase. These 2 products combines produce a cardiolipin and a ethanolamine. The L-1 phosphatidyl-glycerol can also interact with cardiolipin synthase resulting in a glycerol and a cardiolipin.

Phospholipids are membrane components in E. coli. The major phospholipids of E. coli are phosphatidylethanolamine, phosphatidylglycerol and cardiolipin. All phospholipids contain sn-glycerol-3-phosphate esterified with fatty acids at the sn-1 and sn-2 positions. The reaction starts from a glycerone phosphate (dihydroxyacetone phosphate) produced in glycolysis. The glycerone phosphate is transformed to a sn-glycerol 3-phosphate (glycerol 3 phosphate) by NADPH driven glycerol-3-phosphate dehydrogenase. Sn-glycerol 3-phosphate is transformed to a 1-acyl-sn-glycerol 3-phosphate(1-oleyl-2-lyso-phosphatidate , 1-palmitoylglycerol 3-phosphate , 1-stearoyl-sn-glycerol 3-phosphate). This can be achieve by a sn-glycerol-3-phosphate 1-0-acyltransferase that interacts either with a long-chain acyl-CoA or with an acyl-[acp]. The 1-acyl-sn-glycerol 3-phosphate is transformed into a 1,2-diacyl-sn-glycerol 3-phosphate through a 1-acylglycerol-3-phosphate O-acyltransferase. This compound is then converted into a CPD-diacylglycerol through a CTP (phosphatidate cytididyltransferase. CPD-diacylglycerol can be transformed either to a L-1-phosphatidylserine or a L-1-phosphatidylglycerol-phosphate through a phosphatidylserine synthase or a phosphatidylglycerophosphate synthase respectively. The L-1-phosphatidylserine transforms into L-1-phosphatidylethanolamine through a phosphatidylserine decarboxylase, o the other hand L-1-phosphatidylglycerol-phosphate gets transformed into a L-1-phosphatidyl-glycerol through a phosphatidylglycerophosphatase. These 2 products combines produce a cardiolipin and a ethanolamine. The L-1 phosphatidyl-glycerol can also interact with cardiolipin synthase resulting in a glycerol and a cardiolipin.

Phospholipids are membrane components in E. coli. The major phospholipids of E. coli are phosphatidylethanolamine, phosphatidylglycerol and cardiolipin. All phospholipids contain sn-glycerol-3-phosphate esterified with fatty acids at the sn-1 and sn-2 positions. The reaction starts from a glycerone phosphate (dihydroxyacetone phosphate) produced in glycolysis. The glycerone phosphate is transformed to a sn-glycerol 3-phosphate (glycerol 3 phosphate) by NADPH driven glycerol-3-phosphate dehydrogenase. Sn-glycerol 3-phosphate is transformed to a 1-acyl-sn-glycerol 3-phosphate(1-oleyl-2-lyso-phosphatidate , 1-palmitoylglycerol 3-phosphate , 1-stearoyl-sn-glycerol 3-phosphate). This can be achieve by a sn-glycerol-3-phosphate 1-0-acyltransferase that interacts either with a long-chain acyl-CoA or with an acyl-[acp]. The 1-acyl-sn-glycerol 3-phosphate is transformed into a 1,2-diacyl-sn-glycerol 3-phosphate through a 1-acylglycerol-3-phosphate O-acyltransferase. This compound is then converted into a CPD-diacylglycerol through a CTP (phosphatidate cytididyltransferase. CPD-diacylglycerol can be transformed either to a L-1-phosphatidylserine or a L-1-phosphatidylglycerol-phosphate through a phosphatidylserine synthase or a phosphatidylglycerophosphate synthase respectively. The L-1-phosphatidylserine transforms into L-1-phosphatidylethanolamine through a phosphatidylserine decarboxylase, o the other hand L-1-phosphatidylglycerol-phosphate gets transformed into a L-1-phosphatidyl-glycerol through a phosphatidylglycerophosphatase. These 2 products combines produce a cardiolipin and a ethanolamine. The L-1 phosphatidyl-glycerol can also interact with cardiolipin synthase resulting in a glycerol and a cardiolipin.

Phospholipids are membrane components in E. coli. The major phospholipids of E. coli are phosphatidylethanolamine, phosphatidylglycerol and cardiolipin. All phospholipids contain sn-glycerol-3-phosphate esterified with fatty acids at the sn-1 and sn-2 positions. The reaction starts from a glycerone phosphate (dihydroxyacetone phosphate) produced in glycolysis. The glycerone phosphate is transformed to a sn-glycerol 3-phosphate (glycerol 3 phosphate) by NADPH driven glycerol-3-phosphate dehydrogenase. Sn-glycerol 3-phosphate is transformed to a 1-acyl-sn-glycerol 3-phosphate(1-oleyl-2-lyso-phosphatidate , 1-palmitoylglycerol 3-phosphate , 1-stearoyl-sn-glycerol 3-phosphate). This can be achieve by a sn-glycerol-3-phosphate 1-0-acyltransferase that interacts either with a long-chain acyl-CoA or with an acyl-[acp]. The 1-acyl-sn-glycerol 3-phosphate is transformed into a 1,2-diacyl-sn-glycerol 3-phosphate through a 1-acylglycerol-3-phosphate O-acyltransferase. This compound is then converted into a CPD-diacylglycerol through a CTP (phosphatidate cytididyltransferase. CPD-diacylglycerol can be transformed either to a L-1-phosphatidylserine or a L-1-phosphatidylglycerol-phosphate through a phosphatidylserine synthase or a phosphatidylglycerophosphate synthase respectively. The L-1-phosphatidylserine transforms into L-1-phosphatidylethanolamine through a phosphatidylserine decarboxylase, o the other hand L-1-phosphatidylglycerol-phosphate gets transformed into a L-1-phosphatidyl-glycerol through a phosphatidylglycerophosphatase. These 2 products combines produce a cardiolipin and a ethanolamine. The L-1 phosphatidyl-glycerol can also interact with cardiolipin synthase resulting in a glycerol and a cardiolipin.

L-threonine is degrade into methylglyoxal (pyruvaldehyde) by first reacting with a NDA dependent threonine dehydrogenase resulting in the release of a hydrogen ion, an NADH and a 2-amino-3-oxobutanoate. The latter compound reacts spontaneously with a hydrogen ion resulting in the release of a carbon dioxide and a aminoacetone. The aminoacetone in turn reacts with an oxygen and a water molecule through an aminoacetone oxidase resulting in the release of a hydrogen peroxide, ammonium and a methylglyoxal which can then be incorporated in the methylglyoxal degradation pathways.

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.

Fructose metabolism begins with the transport of beta-D-glucose 6-phosphate through a glucose PTS permease. This compound is isomerized by a glucose-6-phosphate isomerase resulting in fructose 6-phosphate. This compound can be phosphorylated by two different enzymes: a pyridoxal phosphatase/fructose 1,6-bisphosphatase or an ATP-driven 6-phosphofructokinase-1, resulting in fructose 1,6-biphosphate. This compound can either react with a fructose bisphosphate aldolase class 1 resulting in D-glyceraldehyde 3-phosphate and dihydroxyacetone phosphate or through a fructose biphosphate aldolase class 2 resulting in D-glyceraldehyde 3-phosphate. This compound can then either react in a reversible triosephosphate isomerase resulting in dihydroxyacetone phosphate or react with a phosphate through an NAD-dependent glyceraldehyde 3-phosphate dehydrogenase resulting in glyceric acid 1,3-biphosphate. This compound is dephosphorylated by a phosphoglycerate kinase resulting in 3-phosphoglyceric acid. This compound, in turn, can either react with a 2,3-bisphosphoglycerate-independent phosphoglycerate mutase or a 2,3-bisphosphoglycerate-independent phosphoglycerate mutase resulting in 2-phospho-D-glyceric acid. This compound interacts with an enolase resulting in a phosphoenolpyruvic acid and water. Phosphoenolpyruvic acid can react either through an AMP-driven phosphoenoylpyruvate synthase or an ADP-driven pyruvate kinase protein complex resulting in pyruvic acid. The pyruvic acid reacts with CoA through an NAD-driven pyruvate dehydrogenase complex resulting in carbon dioxide and an acetyl-CoA which gets incorporated into the TCA cycle pathway.

The citric acid cycle (also named tricarboxylic acid (TCA) cycle or the Krebs cycle), is a collection of 9 enzyme-catalyzed chemical reactions that occur in all living cells undergoing aerobic respiration. The citric acid cycle itself was officially identified in 1937 by Hans Adolf Krebs, who received the Nobel Prize for this discovery in 1953. In eukaryotes, the citric acid cycle occurs in the mitochondria. In prokaryotes, the TCA cycle occurs in the cytoplasm. The TCA cycle starts with acetyl-CoA, which is the “fuel” for the entire cycle. This important molecule comes from the breakdown of glycogen (a stored form of glucose), fats, and many amino acids. At beginning, acetyl-CoA first transfers its 2-carbon acetyl group to the 4-carbon acceptor compound called oxaloacetate to form the 6-carbon compound (citrate) for which the cycle is named. The resulting citrate will have numbers of chemical transformations, whereby it loses one carboxyl group (leading to the 5-carbon compound called alpha-ketoglutarate) and then a second carboxyl group (leading to the 4-carbon compound called succinate). Succinate molecule is further oxidized to fumarate, then malate and finally oxaloacetate. The regeneration of the 4-carbon oxaloacetate, allows the TCA cycle to continue. Oxidation step generates energy that is transferring energy-rich electrons for NAD+ to form NADH in TCA cycle. Each acetyl group will generate 3 NADH in TCA cycle.

This pathway demonstrate the biosynthesis of thiazole moiety in E.coli K-12 strain and Salmonella enterica serovar Typhimurium. L-Tyrosine is generated from tyrosine biosynthesis. With S-Adenosylmethionine and NADPH, L-Tyrosine can be catalyzed into four different small molecules: 4-methylcatechol, dehydroglycine, 5'-deoxyadenosine and L-methionine as well as NADP by dehydroglycine synthase (encoded by thiH gene). Meanwhile, 1-deoxyxylulose-5-phosphate synthase (encoded by dxs gene) catalyzes pyruvic acid and D-Glyceraldehyde 3-phosphate into 1-Deoxy-D-xylulose 5-phosphate. The final reaction of the pathway is facilitated by thiazole synthase (encoded by thiG and thiH), which require a thiocarboxy-[ThiS-Protein], 1-deoxy-D-xylulose 5-phosphate and 2-iminoacetate to form 2-((2R,5Z)-2-Carboxy-4-methylthiazol-5(2H)-ylidene)ethyl phosphate for Thiamin Diphosphate Biosynthesis, as well as a ThiS sulfur-carrier protein and water.