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Mol Biol Cell. 2018 Oct 24:mbcE18080515. doi: 10.1091/mbc.E18-08-0515. [Epub ahead of print]

Methionine coordinates a hierarchically organized anabolic program enabling proliferation.

Author information

1
Institute for Stem Cell biology and Regenerative Medicine (inStem), NCBS-TIFR campus, GKVK Post, Bellary Road, Bangalore 560065.

Abstract

Methionine availability during overall amino acid limitation metabolically reprograms cells to support proliferation, the underlying basis for which remains unclear. Here, we construct the organization of this methionine mediated anabolic program, using yeast. Combining comparative transcriptome analysis, biochemical and metabolic flux based approaches, we discover that methionine rewires overall metabolic outputs by increasing the activity of a key regulatory node. This comprises of: the pentose phosphate pathway (PPP) coupled with reductive biosynthesis, the glutamate dehydrogenase (GDH) dependent synthesis of glutamate/glutamine, and pyridoxal-5-phosphate (PLP) dependent transamination capacity. This PPP-GDH-PLP node provides the required cofactors and/or substrates for subsequent rate-limiting reactions in the synthesis of amino acids, and therefore nucleotides. These rate-limiting steps in amino acid biosynthesis are also induced in a methionine-dependent manner. This thereby results in a biochemical cascade establishing a hierarchically organized anabolic program. For this methionine mediated anabolic program to be sustained, cells co-opt a "starvation stress response" regulator, Gcn4p. Collectively, our data suggest a hierarchical metabolic framework explaining how methionine mediates an anabolic switch.

PMID:
30354837
DOI:
10.1091/mbc.E18-08-0515

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