Browsing 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.

The metabolism of 1-Acyl-sn-glycero-3-phosphoethanolamine compounds represents a tightly coordinated sequence of biosynthetic and degradative processes that connect lipid metabolism with central carbon pathways such as glycolysis. The pathway typically begins with the formation of glycerol 3-phosphate, generated through the NADPH-dependent reduction of dihydroxyacetone phosphate (DHAP) by glycerol-3-phosphate dehydrogenase, linking the lipid pathway to glycolytic intermediates. This glycerol 3-phosphate then serves as a foundational scaffold for phospholipid biosynthesis. In the first acylation step, glycerol-3-phosphate acyltransferase transfers an acyl group from a corresponding acyl-CoA (such as lauroyl-, myristoyl-, or palmitoyl-CoA) to the sn-1 position, producing a lysophosphatidic acid (LysoPA) species. A second acyl chain, typically unsaturated, is added at the sn-2 position by 1-acylglycerol-3-phosphate O-acyltransferase, forming a fully acylated phosphatidic acid (PA). This PA is then activated by CDP-diglyceride synthetase using cytidine triphosphate (CTP) to yield CDP-diacylglycerol (CDP-DG), a key intermediate in the biosynthesis of phospholipids. Through the action of phosphatidylserine synthase, L-serine is incorporated to form phosphatidylserine (PS), which is subsequently decarboxylated by phosphatidylserine decarboxylase to produce phosphatidylethanolamine (PE). This PE can then undergo N-acylation of its ethanolamine headgroup, catalyzed by phospholipase A1, which transfers an additional acyl group (often saturated) from an acyl-CoA to form 1-Acyl-sn-glycero-3-phosphoethanolamine (N-acyl-PE). At this point, the N-acyl-PE molecule may function as a membrane-associated signaling or structural lipid. However, it can also be routed back into central metabolism. Glycerophosphoryl diester phosphodiesterase hydrolyzes the compound to yield 1-acyl-sn-glycerol 3-phosphate, ethanolamine, and a proton. The liberated ethanolamine is further catabolized by ethanolamine ammonia-lyase, which converts it into acetaldehyde and ammonia. Acetaldehyde is then oxidized by acetaldehyde dehydrogenase in the presence of NAD⁺ and Coenzyme A to form acetyl-CoA, a core metabolic intermediate that feeds directly into the TCA cycle or glycolysis via the acetyl-CoA.

The metabolism of 1-Acyl-sn-glycero-3-phosphoethanolamine compounds represents a tightly coordinated sequence of biosynthetic and degradative processes that connect lipid metabolism with central carbon pathways such as glycolysis. The pathway typically begins with the formation of glycerol 3-phosphate, generated through the NADPH-dependent reduction of dihydroxyacetone phosphate (DHAP) by glycerol-3-phosphate dehydrogenase, linking the lipid pathway to glycolytic intermediates. This glycerol 3-phosphate then serves as a foundational scaffold for phospholipid biosynthesis. In the first acylation step, glycerol-3-phosphate acyltransferase transfers an acyl group from a corresponding acyl-CoA (such as lauroyl-, myristoyl-, or palmitoyl-CoA) to the sn-1 position, producing a lysophosphatidic acid (LysoPA) species. A second acyl chain, typically unsaturated, is added at the sn-2 position by 1-acylglycerol-3-phosphate O-acyltransferase, forming a fully acylated phosphatidic acid (PA). This PA is then activated by CDP-diglyceride synthetase using cytidine triphosphate (CTP) to yield CDP-diacylglycerol (CDP-DG), a key intermediate in the biosynthesis of phospholipids. Through the action of phosphatidylserine synthase, L-serine is incorporated to form phosphatidylserine (PS), which is subsequently decarboxylated by phosphatidylserine decarboxylase to produce phosphatidylethanolamine (PE). This PE can then undergo N-acylation of its ethanolamine headgroup, catalyzed by phospholipase A1, which transfers an additional acyl group (often saturated) from an acyl-CoA to form 1-Acyl-sn-glycero-3-phosphoethanolamine (N-acyl-PE). At this point, the N-acyl-PE molecule may function as a membrane-associated signaling or structural lipid. However, it can also be routed back into central metabolism. Glycerophosphoryl diester phosphodiesterase hydrolyzes the compound to yield 1-acyl-sn-glycerol 3-phosphate, ethanolamine, and a proton. The liberated ethanolamine is further catabolized by ethanolamine ammonia-lyase, which converts it into acetaldehyde and ammonia. Acetaldehyde is then oxidized by acetaldehyde dehydrogenase in the presence of NAD⁺ and Coenzyme A to form acetyl-CoA, a core metabolic intermediate that feeds directly into the TCA cycle or glycolysis via the acetyl-CoA.

The metabolism of 1-Acyl-sn-glycero-3-phosphoethanolamine compounds represents a tightly coordinated sequence of biosynthetic and degradative processes that connect lipid metabolism with central carbon pathways such as glycolysis. The pathway typically begins with the formation of glycerol 3-phosphate, generated through the NADPH-dependent reduction of dihydroxyacetone phosphate (DHAP) by glycerol-3-phosphate dehydrogenase, linking the lipid pathway to glycolytic intermediates. This glycerol 3-phosphate then serves as a foundational scaffold for phospholipid biosynthesis. In the first acylation step, glycerol-3-phosphate acyltransferase transfers an acyl group from a corresponding acyl-CoA (such as lauroyl-, myristoyl-, or palmitoyl-CoA) to the sn-1 position, producing a lysophosphatidic acid (LysoPA) species. A second acyl chain, typically unsaturated, is added at the sn-2 position by 1-acylglycerol-3-phosphate O-acyltransferase, forming a fully acylated phosphatidic acid (PA). This PA is then activated by CDP-diglyceride synthetase using cytidine triphosphate (CTP) to yield CDP-diacylglycerol (CDP-DG), a key intermediate in the biosynthesis of phospholipids. Through the action of phosphatidylserine synthase, L-serine is incorporated to form phosphatidylserine (PS), which is subsequently decarboxylated by phosphatidylserine decarboxylase to produce phosphatidylethanolamine (PE). This PE can then undergo N-acylation of its ethanolamine headgroup, catalyzed by phospholipase A1, which transfers an additional acyl group (often saturated) from an acyl-CoA to form 1-Acyl-sn-glycero-3-phosphoethanolamine (N-acyl-PE). At this point, the N-acyl-PE molecule may function as a membrane-associated signaling or structural lipid. However, it can also be routed back into central metabolism. Glycerophosphoryl diester phosphodiesterase hydrolyzes the compound to yield 1-acyl-sn-glycerol 3-phosphate, ethanolamine, and a proton. The liberated ethanolamine is further catabolized by ethanolamine ammonia-lyase, which converts it into acetaldehyde and ammonia. Acetaldehyde is then oxidized by acetaldehyde dehydrogenase in the presence of NAD⁺ and Coenzyme A to form acetyl-CoA, a core metabolic intermediate that feeds directly into the TCA cycle or glycolysis via the acetyl-CoA.

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 into an 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 (lysophosphatidic acid). This can be achieved by an sn-glycerol-3-phosphate 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 (phosphatidic acid) 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 into an L-1-phosphatidylserine or an 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. On the other hand, L-1-phosphatidylglycerol-phosphate gets transformed into an L-1-phosphatidyl-glycerol through a phosphatidylglycerophosphatase. These 2 products combine to produce a cardiolipin and an ethanolamine. The L-1 phosphatidyl-glycerol can also interact with cardiolipin synthase resulting in a glycerol and a cardiolipin.

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.

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.

The metabolism of 1-Acyl-sn-glycero-3-phosphoethanolamine compounds represents a tightly coordinated sequence of biosynthetic and degradative processes that connect lipid metabolism with central carbon pathways such as glycolysis. The pathway typically begins with the formation of glycerol 3-phosphate, generated through the NADPH-dependent reduction of dihydroxyacetone phosphate (DHAP) by glycerol-3-phosphate dehydrogenase, linking the lipid pathway to glycolytic intermediates. This glycerol 3-phosphate then serves as a foundational scaffold for phospholipid biosynthesis. In the first acylation step, glycerol-3-phosphate acyltransferase transfers an acyl group from a corresponding acyl-CoA (such as lauroyl-, myristoyl-, or palmitoyl-CoA) to the sn-1 position, producing a lysophosphatidic acid (LysoPA) species. A second acyl chain, typically unsaturated, is added at the sn-2 position by 1-acylglycerol-3-phosphate O-acyltransferase, forming a fully acylated phosphatidic acid (PA). This PA is then activated by CDP-diglyceride synthetase using cytidine triphosphate (CTP) to yield CDP-diacylglycerol (CDP-DG), a key intermediate in the biosynthesis of phospholipids. Through the action of phosphatidylserine synthase, L-serine is incorporated to form phosphatidylserine (PS), which is subsequently decarboxylated by phosphatidylserine decarboxylase to produce phosphatidylethanolamine (PE). This PE can then undergo N-acylation of its ethanolamine headgroup, catalyzed by phospholipase A1, which transfers an additional acyl group (often saturated) from an acyl-CoA to form 1-Acyl-sn-glycero-3-phosphoethanolamine (N-acyl-PE). At this point, the N-acyl-PE molecule may function as a membrane-associated signaling or structural lipid. However, it can also be routed back into central metabolism. Glycerophosphoryl diester phosphodiesterase hydrolyzes the compound to yield 1-acyl-sn-glycerol 3-phosphate, ethanolamine, and a proton. The liberated ethanolamine is further catabolized by ethanolamine ammonia-lyase, which converts it into acetaldehyde and ammonia. Acetaldehyde is then oxidized by acetaldehyde dehydrogenase in the presence of NAD⁺ and Coenzyme A to form acetyl-CoA, a core metabolic intermediate that feeds directly into the TCA cycle or glycolysis via the acetyl-CoA.