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.

2-O-α-Mannosyl-D-glycerate (MG; also named as Alpha-Mannosylglycerate) is an organic compound that will affect the osmosis in hyperthermophilic archaea and bacteria. In E.coli, 2-O-α-mannosyl-D-glycerate PTS permease (mngA) import MG into cell, and then phosphorylate MG to 2-O-(6-phospho-α-mannosyl)-D-glycerate by phosphocarrier protein HPr. 2-O-(6-phospho-α-mannosyl)-D-glycerate is converted to glyceric acid as well as mannose 6-phosphate by alpha-mannosidase mngB. Finally, glyceric acid is catalyzed to 2-Phospho-D-glyceric acid with ATP as energy source by Glycerate kinase 2. E.coli can't use MG as osmotic stress protection, but it can use MG as a carbon source.

ADP-L-glycero-β-D-manno-heptose is a precursor for the inner core lipopolysaccharide (LPS), which is the outer membrane of Gram-negative bacteria. LPS is consisted of lipid A, a core oligosaccharide, and an O-specific polysaccharide (O antigen). This biosynthesis pathway starts with catalyzation of D-sedoheptulose 7-phosphate that produced from pentose phosphate pathway to form D-glycero-D-manno-heptose 7-phosphate by lysophospholipid acyltransferase. D-glycero-D-manno-heptose 7-phosphate later undergoes catalyze to form D-glycero-β-D-manno-heptose 1,7-bisphosphate by fused heptose 7-phosphate kinase (also known as heptose 1-phosphate adenyltransferase) that powered by ATP. D-glycero-β-D-manno-heptose 1,7-bisphosphate will go through hydrolysis by D,D-heptose 1,7-bisphosphate phosphatase to form D-glycero-β-D-manno-heptose 1-phosphate and a phosphate. D-glycero-β-D-manno-heptose 1-phosphate will form ADP-D-Glycero-D-manno-heptose and diphosphate, and eventually ADP-D-Glycero-D-manno-heptose will be biotransformed to ADP-L-glycero-β-D-manno-heptose as the end product of this pathway by ADP-L-glycero-D-mannoheptose-6-epimerase.

ADP-L-glycero-β-D-manno-heptose is a precursor for the inner core lipopolysaccharide (LPS), which is the outer membrane of Gram-negative bacteria. LPS is consisted of lipid A, a core oligosaccharide, and an O-specific polysaccharide (O antigen). This biosynthesis pathway starts with catalyzation of D-sedoheptulose 7-phosphate that produced from pentose phosphate pathway to form D-glycero-D-manno-heptose 7-phosphate by lysophospholipid acyltransferase. D-glycero-D-manno-heptose 7-phosphate later undergoes catalyze to form D-glycero-β-D-manno-heptose 1,7-bisphosphate by fused heptose 7-phosphate kinase (also known as heptose 1-phosphate adenyltransferase) that powered by ATP. D-glycero-β-D-manno-heptose 1,7-bisphosphate will go through hydrolysis by D,D-heptose 1,7-bisphosphate phosphatase to form D-glycero-β-D-manno-heptose 1-phosphate and a phosphate. D-glycero-β-D-manno-heptose 1-phosphate will form ADP-D-Glycero-D-manno-heptose and diphosphate, and eventually ADP-D-Glycero-D-manno-heptose will be biotransformed to ADP-L-glycero-β-D-manno-heptose as the end product of this pathway by ADP-L-glycero-D-mannoheptose-6-epimerase.

ADP-L-glycero-β-D-manno-heptose is a precursor for the inner core lipopolysaccharide (LPS), which is the outer membrane of Gram-negative bacteria. LPS is consisted of lipid A, a core oligosaccharide, and an O-specific polysaccharide (O antigen). This biosynthesis pathway starts with catalyzation of D-sedoheptulose 7-phosphate that produced from pentose phosphate pathway to form D-glycero-D-manno-heptose 7-phosphate by lysophospholipid acyltransferase. D-glycero-D-manno-heptose 7-phosphate later undergoes catalyze to form D-glycero-β-D-manno-heptose 1,7-bisphosphate by fused heptose 7-phosphate kinase (also known as heptose 1-phosphate adenyltransferase) that powered by ATP. D-glycero-β-D-manno-heptose 1,7-bisphosphate will go through hydrolysis by D,D-heptose 1,7-bisphosphate phosphatase to form D-glycero-β-D-manno-heptose 1-phosphate and a phosphate. D-glycero-β-D-manno-heptose 1-phosphate will form ADP-D-Glycero-D-manno-heptose and diphosphate, and eventually ADP-D-Glycero-D-manno-heptose will be biotransformed to ADP-L-glycero-β-D-manno-heptose as the end product of this pathway by ADP-L-glycero-D-mannoheptose-6-epimerase.

Sedoheptulose bisphospate bypass pathway demonstrates a series of reaction that form D-Erythrose 4-phosphate for pentose phosphate pathway and glycerone phosphate for glycolysis and pyruvate dehydrogenase pathway. D-Sedoheptulose 7-phosphate is obtained from pentose phosphate pathway, which later converted to sedoheptulose 1,7-bisphosphate via 6-phosphofructokinase-1. Fructose-bisphosphate aldolase class 2 catalyzes sedoheptulose 1,7-bisphosphate to form D-Erythrose 4-phosphate and pyruvate dehydrogenase.

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.

ADP-L-glycero-β-D-manno-heptose is a precursor for the inner core lipopolysaccharide (LPS), which is the outer membrane of Gram-negative bacteria. LPS is consisted of lipid A, a core oligosaccharide, and an O-specific polysaccharide (O antigen). This biosynthesis pathway starts with catalyzation of D-sedoheptulose 7-phosphate that produced from pentose phosphate pathway to form D-glycero-D-manno-heptose 7-phosphate by lysophospholipid acyltransferase. D-glycero-D-manno-heptose 7-phosphate later undergoes catalyze to form D-glycero-β-D-manno-heptose 1,7-bisphosphate by fused heptose 7-phosphate kinase (also known as heptose 1-phosphate adenyltransferase) that powered by ATP. D-glycero-β-D-manno-heptose 1,7-bisphosphate will go through hydrolysis by D,D-heptose 1,7-bisphosphate phosphatase to form D-glycero-β-D-manno-heptose 1-phosphate and a phosphate. D-glycero-β-D-manno-heptose 1-phosphate will form ADP-D-Glycero-D-manno-heptose and diphosphate, and eventually ADP-D-Glycero-D-manno-heptose will be biotransformed to ADP-L-glycero-β-D-manno-heptose as the end product of this pathway by ADP-L-glycero-D-mannoheptose-6-epimerase.