L-methionine salvage from methylthioadenosine

Definition

Target type: biologicalprocess

The generation of L-methionine (2-amino-4-(methylthio)butanoic acid) from methylthioadenosine. [GOC:jl, MetaCyc:PWY-4361]

L-methionine salvage from methylthioadenosine is a crucial metabolic pathway for recycling sulfur and methyl groups. The process begins with the conversion of S-adenosyl-L-methionine (SAM), a universal methyl donor, into S-adenosyl-L-homocysteine (SAH) during various metabolic reactions. SAH is then hydrolyzed to adenosine and homocysteine. Homocysteine can be remethylated back to methionine, a process requiring tetrahydrofolate and cobalamin (vitamin B12). However, methionine can also be generated via the salvage pathway utilizing methylthioadenosine (MTA). MTA is produced during polyamine biosynthesis, a process essential for cell growth and differentiation. The salvage pathway commences with the enzyme methylthioadenosine phosphorylase (MTAP), which cleaves MTA into adenine and methylthioribose-1-phosphate (MTR1P). MTR1P is then converted to methionine through a series of enzymatic reactions. Firstly, MTR1P is hydrolyzed by the enzyme MTR1P phosphatase to methylthioribose. This is followed by the action of the enzyme methylthioribose kinase, which phosphorylates methylthioribose to methylthioribose-1-phosphate. Subsequently, the enzyme methionine synthase catalyzes the transfer of a methyl group from 5-methyltetrahydrofolate to methylthioribose-1-phosphate, producing methionine and tetrahydrofolate. This methionine salvage pathway allows cells to efficiently recycle methionine, a crucial amino acid for protein synthesis, while also providing a pathway for sulfur and methyl group recovery. The salvage pathway also prevents the accumulation of MTA, a toxic byproduct of polyamine biosynthesis, thus maintaining cellular homeostasis.'
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Proteins (2)

Compounds (4)