Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

Cystathionine beta-lyase, PLP-dependent; Primarily catalyzes the cleavage of cystathionine to homocysteine, pyruvate and ammonia during methionine biosynthesis. Also exhibits cysteine desulfhydrase activity, producing sulfide from cysteine. In addition, under certain growth conditions, exhibits significant alanine racemase coactivity.

Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

5-methyltetrahydropteroyltriglutamate- homocysteine S-methyltransferase; Catalyzes the transfer of a methyl group from 5- methyltetrahydrofolate to homocysteine resulting in methionine formation.

Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

5,10-methylenetetrahydrofolate reductase; Methylenetetrahydrofolate reductase required to generate the methyl groups necessary for methionine synthetase to convert homocysteine to methionine.

Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

DL-methionine transporter subunit; Part of the binding-protein-dependent transport system for D- methionine and the toxic methionine analog alpha-methyl-methionine. Probably responsible for the translocation of the substrate across the membrane.

Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

S-adenosylmethionine synthetase; Catalyzes the formation of S-adenosylmethionine (AdoMet) from methionine and ATP. The overall synthetic reaction is composed of two sequential steps, AdoMet formation and the subsequent tripolyphosphate hydrolysis which occurs prior to release of AdoMet from the enzyme. Is essential for growth.

Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

Bifunctional aspartokinase/homoserine dehydrogenase 2; Aspartokinase II and homoserine dehydrogenase II; Protein involved in methionine biosynthetic process and homoserine biosynthetic process.

Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

DL-methionine transporter subunit; Part of the ABC transporter complex MetNIQ involved in methionine import. Responsible for energy coupling to the transport system. It has also been shown to be involved in formyl-L-methionine transport. Belongs to the ABC transporter superfamily. Methionine importer (TC 3.A.1.24) family.

Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

Methionine biosynthesis regulon transcriptional regulator; Control of the last step in methionine biosynthesis; MetR is a positive activator of the metA, metE and metH genes. MetR is also a negative regulator of its own expression. Binds homocysteine as an inducer; Belongs to the LysR transcriptional regulatory family.

Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

Bifunctional: aspartokinase I (N-terminal); homoserine dehydrogenase I (C-terminal); Protein involved in threonine biosynthetic process, methionine biosynthetic process and homoserine biosynthetic process.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

Homoserine O-transsuccinylase; Transfers a succinyl group from succinyl-CoA to L-homoserine, forming succinyl-L-homoserine. Utilizes a ping-pong kinetic mechanism in which the succinyl group of succinyl-CoA is initially transferred to the enzyme to form a succinyl-enzyme intermediate before subsequent transfer to homoserine to form the final product, O- succinylhomoserine. Cannot use acetyl-CoA. Belongs to the MetA family.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

Cystathionine beta-lyase, PLP-dependent; Primarily catalyzes the cleavage of cystathionine to homocysteine, pyruvate and ammonia during methionine biosynthesis. Also exhibits cysteine desulfhydrase activity, producing sulfide from cysteine. In addition, under certain growth conditions, exhibits significant alanine racemase coactivity.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

5-methyltetrahydropteroyltriglutamate- homocysteine S-methyltransferase; Catalyzes the transfer of a methyl group from 5- methyltetrahydrofolate to homocysteine resulting in methionine formation.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

5,10-methylenetetrahydrofolate reductase; Methylenetetrahydrofolate reductase required to generate the methyl groups necessary for methionine synthetase to convert homocysteine to methionine.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

DL-methionine transporter subunit; Part of the binding-protein-dependent transport system for D- methionine and the toxic methionine analog alpha-methyl-methionine. Probably responsible for the translocation of the substrate across the membrane.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

S-adenosylmethionine synthetase; Catalyzes the formation of S-adenosylmethionine (AdoMet) from methionine and ATP. The overall synthetic reaction is composed of two sequential steps, AdoMet formation and the subsequent tripolyphosphate hydrolysis which occurs prior to release of AdoMet from the enzyme. Is essential for growth.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

Bifunctional aspartokinase/homoserine dehydrogenase 2; Aspartokinase II and homoserine dehydrogenase II; Protein involved in methionine biosynthetic process and homoserine biosynthetic process.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

DL-methionine transporter subunit; Part of the ABC transporter complex MetNIQ involved in methionine import. Responsible for energy coupling to the transport system. It has also been shown to be involved in formyl-L-methionine transport. Belongs to the ABC transporter superfamily. Methionine importer (TC 3.A.1.24) family.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

Methionine biosynthesis regulon transcriptional regulator; Control of the last step in methionine biosynthesis; MetR is a positive activator of the metA, metE and metH genes. MetR is also a negative regulator of its own expression. Binds homocysteine as an inducer; Belongs to the LysR transcriptional regulatory family.

Cystathionine gamma-synthase, PLP-dependent; Catalyzes the formation of L-cystathionine from O-succinyl-L- homoserine (OSHS) and L-cysteine, via a gamma-replacement reaction. In the absence of thiol, catalyzes gamma-elimination to form 2- oxobutanoate, succinate and ammonia.

Bifunctional: aspartokinase I (N-terminal); homoserine dehydrogenase I (C-terminal); Protein involved in threonine biosynthetic process, methionine biosynthetic process and homoserine biosynthetic process.