Browsing Pathways

Phosphatidylinositol (PI) biosynthesis in bacteria is a multistep enzymatic process that begins with the formation of glycerol 3-phosphate from dihydroxyacetone phosphate, catalyzed by glycerol-3-phosphate dehydrogenase. This initial step provides the glycerol backbone essential for subsequent acylation reactions. Glycerol-3-phosphate is first acylated at the sn-1 position by glycerol-3-phosphate acyltransferase, which transfers a fatty acyl group from acyl-CoA (for example, 3-hydroxydodecanoyl-CoA) to form lysophosphatidic acid (LysoPA), specifically LysoPA(12:0/0:0). The sn-2 position of LysoPA is then acylated by 1-acylglycerol-3-phosphate O-acyltransferase using a second fatty acyl donor, such as oleoyl-CoA, generating phosphatidic acid (PA(12:0/18:1(9Z))). Phosphatidic acid is subsequently activated through the formation of CDP-diacylglycerol (CDP-DG) in a reaction catalyzed by CDP-diglyceride synthetase, which consumes cytidine triphosphate and releases pyrophosphate. The CDP-DG intermediate then reacts with myo-inositol in a reaction catalyzed by CDP-diacylglycerol–glycerol-3-phosphate 3-phosphatidyltransferase, producing phosphatidylinositol with an empty sn-2 position (PI(12:0/0:0)) and releasing cytidine monophosphate and a proton. The final step, introducing the sn-2 fatty acyl group to form the mature PI species, such as PI(12:0/14:1(9Z)), is carried out by a membrane-bound O-acyltransferase (MBOAT) that transfers an acyl group from acyl-CoA (e.g., myristoleoyl-CoA) to the sn-2 position of PI. This step is poorly characterized in most bacteria, and the specific enzyme(s) responsible remain largely unannotated in bacterial genomes. Overall, bacterial PI biosynthesis demonstrates a tightly coordinated sequence of acylation, activation, and inositol transfer reactions, culminating in the formation of functionally diverse phosphatidylinositol species that contribute to membrane structure and signaling.

Phosphatidylinositol (PI) biosynthesis in bacteria is a multistep enzymatic process that begins with the formation of glycerol 3-phosphate from dihydroxyacetone phosphate, catalyzed by glycerol-3-phosphate dehydrogenase. This initial step provides the glycerol backbone essential for subsequent acylation reactions. Glycerol-3-phosphate is first acylated at the sn-1 position by glycerol-3-phosphate acyltransferase, which transfers a fatty acyl group from acyl-CoA (for example, 3-hydroxydodecanoyl-CoA) to form lysophosphatidic acid (LysoPA), specifically LysoPA(12:0/0:0). The sn-2 position of LysoPA is then acylated by 1-acylglycerol-3-phosphate O-acyltransferase using a second fatty acyl donor, such as oleoyl-CoA, generating phosphatidic acid (PA(12:0/18:1(9Z))). Phosphatidic acid is subsequently activated through the formation of CDP-diacylglycerol (CDP-DG) in a reaction catalyzed by CDP-diglyceride synthetase, which consumes cytidine triphosphate and releases pyrophosphate. The CDP-DG intermediate then reacts with myo-inositol in a reaction catalyzed by CDP-diacylglycerol–glycerol-3-phosphate 3-phosphatidyltransferase, producing phosphatidylinositol with an empty sn-2 position (PI(12:0/0:0)) and releasing cytidine monophosphate and a proton. The final step, introducing the sn-2 fatty acyl group to form the mature PI species, such as PI(12:0/14:1(9Z)), is carried out by a membrane-bound O-acyltransferase (MBOAT) that transfers an acyl group from acyl-CoA (e.g., myristoleoyl-CoA) to the sn-2 position of PI. This step is poorly characterized in most bacteria, and the specific enzyme(s) responsible remain largely unannotated in bacterial genomes. Overall, bacterial PI biosynthesis demonstrates a tightly coordinated sequence of acylation, activation, and inositol transfer reactions, culminating in the formation of functionally diverse phosphatidylinositol species that contribute to membrane structure and signaling.

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.

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.

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.