PathBank

Pathway Description

Methionine Biosynthesis

Cetobacterium somerae ATCC BAA-474

Category:

Metabolite Pathway

Sub-Category:

Metabolic

Created: 2024-12-21

Last Updated: 2025-08-11

This pathway shows the biosynthesis of methionine, which is an energy-costly process. Lysine biosynthesis produces L-Aspartate-semialdehyde, which later on is catalyzed to L-homoserine by bifunctional aspartokinase (also named homoserine dehydrogenase) 1 and 2. Homoserine is then activated by O-succinylation to form O-succinyl-L-homoserine via homoserine O-succinyltransferase (metA). Combining with L-cysteine, O-succinyl-L-homoserine form L-cystathionine and succinic acid by cystathionine gamma-synthase (metB). Cleavage of L-cystathionine by cystathionine beta-lyase (metC) or Protein MalY(as ) generates two small molecules: homocysteine and 2-aminoprop-2-enoate. Methionine synthase(MetH) or 5-methyltetrahydropteroyltriglutamate--homocysteine methyltransferase(MetE) will catalyzehomocysteine to form the final product: methionine. In E.coli, MetH can only function with existence of cobalamin (Vitamin B12), which can be available in the guy; without cobalamin, MetE will not be repressed so that it will catalyze the methionine. Methionine can be transported out of cell (into periplasmic space) by leucine efflux transporter.

References

Methionine Biosynthesis References

This pathway was propagated using PathWhiz - Pon, A. et al. Pathways with PathWhiz (2015) Nucleic Acids Res. 43(Web Server issue): W552–W559.

Propagated from SMP0000834

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Visualize Compound Data

		N5-methyl--tetrahydropteroyl tri-L-glutamate
		2-aminoprop-2-enoate
		Coenzyme A
		Homocysteine
		Hydrogen Ion
		L-Aspartate-semialdehyde
		L-Cystathionine
		L-Cysteine
		L-Homoserine
		L-Methionine
		N5-methyl--tetrahydropteroyl tri-L-glutamate
		NADP
		NADPH
		O-succinyl-L-homoserine
		S-Methylmethionine
		Succinic acid
		Succinyl-CoA
		Tetrahydropteroyltri-L-glutamate

Visualize Protein Data

		Aspartokinase
		Hcy-binding domain-containing protein
		Homoserine O-acetyltransferase
		L-methionine gamma-lyase
		Lysine exporter LysO family protein
		Methionine synthase
		Peptidase M20 dimerisation domain-containing protein