Diversification of Paralogous α-Isopropylmalate Synthases by Modulation of Feedback Control and Hetero-Oligomerization in Saccharomyces cerevisiae. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Eukaryotic Cell Année : 2015

Diversification of Paralogous α-Isopropylmalate Synthases by Modulation of Feedback Control and Hetero-Oligomerization in Saccharomyces cerevisiae.

Résumé

Production of α-isopropylmalate (α-IPM) is critical for leucine biosynthesis and for the global control of metabolism. The budding yeast Saccharomyces cerevisiae has two paralogous genes, LEU4 and LEU9, that encode α-IPM synthase (α-IPMS) isozymes. Little is known about the biochemical differences between these two α-IPMS isoenzymes. Here, we show that the Leu4 homodimer is a leucine-sensitive isoform, while the Leu9 homodimer is resistant to such feedback inhibition. The leu4Δ mutant, which expresses only the feedback-resistant Leu9 homodimer, grows slowly with either glucose or ethanol and accumulates elevated pools of leucine; this phenotype is alleviated by the addition of leucine. Transformation of the leu4Δ mutant with a centromeric plasmid carrying LEU4 restored the wild-type phenotype. Bimolecular fluorescent complementation analysis showed that Leu4-Leu9 heterodimeric isozymes are formed in vivo. Purification and kinetic analysis showed that the hetero-oligomeric isozyme has a distinct leucine sensitivity behavior. Determination of α-IPMS activity in ethanol-grown cultures showed that α-IPM biosynthesis and growth under these respiratory conditions depend on the feedback-sensitive Leu4 homodimer. We conclude that retention and further diversification of two yeast α-IPMSs have resulted in a specific regulatory system that controls the leucine-α-IPM biosynthetic pathway by selective feedback sensitivity of homomeric and heterodimeric isoforms.

Dates et versions

hal-01434909 , version 1 (13-01-2017)

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Geovani López, Héctor Quezada, Mariana Duhne, James González, Mijail Lezama, et al.. Diversification of Paralogous α-Isopropylmalate Synthases by Modulation of Feedback Control and Hetero-Oligomerization in Saccharomyces cerevisiae.. Eukaryotic Cell, 2015, 14 (6), pp.564-77. ⟨10.1128/EC.00033-15⟩. ⟨hal-01434909⟩
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