RRC ID 12334
Author Michaeli S, Fait A, Lagor K, Nunes-Nesi A, Grillich N, Yellin A, Bar D, Khan M, Fernie AR, Turano FJ, Fromm H.
Title A mitochondrial GABA permease connects the GABA shunt and the TCA cycle, and is essential for normal carbon metabolism.
Journal Plant J
Abstract In plants, γ-aminobutyric acid (GABA) accumulates in the cytosol in response to a variety of stresses. GABA is transported into mitochondria, where it is catabolized into TCA cycle or other intermediates. Although there is circumstantial evidence for mitochondrial GABA transporters in eukaryotes, none have yet been identified. Described here is an Arabidopsis protein similar in sequence and topology to unicellular GABA transporters. The expression of this protein complements a GABA-transport-deficient yeast mutant. Thus the protein was termed AtGABP to indicate GABA-permease activity. In vivo localization of GABP fused to GFP and immunobloting of subcellular fractions demonstrate its mitochondrial localization. Direct [(3) H]GABA uptake measurements into isolated mitochondria revealed impaired uptake into mitochondria of a gabp mutant compared with wild-type (WT) mitochondria, implicating AtGABP as a major mitochondrial GABA carrier. Measurements of CO(2) release, derived from radiolabeled substrates in whole seedlings and in isolated mitochondria, demonstrate impaired GABA-derived input into the TCA cycle, and a compensatory increase in TCA cycle activity in gabp mutants. Finally, growth abnormalities of gabp mutants under limited carbon availability on artificial media, and in soil under low light intensity, combined with their metabolite profiles, suggest an important role for AtGABP in primary carbon metabolism and plant growth. Thus, AtGABP-mediated transport of GABA from the cytosol into mitochondria is important to ensure proper GABA-mediated respiration and carbon metabolism. This function is particularly essential for plant growth under conditions of limited carbon.
Volume 67(3)
Pages 485-98
Published 2011-8-1
DOI 10.1111/j.1365-313X.2011.04612.x
PMID 21501262
MeSH Amino Acid Sequence Analysis of Variance Arabidopsis / enzymology* Arabidopsis / genetics Arabidopsis / growth & development Arabidopsis Proteins / genetics Arabidopsis Proteins / metabolism* Blotting, Southern Carbon / metabolism Carbon Dioxide / metabolism Citric Acid Cycle* Cytosol / metabolism GABA Plasma Membrane Transport Proteins / genetics GABA Plasma Membrane Transport Proteins / metabolism* Genetic Complementation Test Genetic Vectors Genotype Green Fluorescent Proteins / metabolism Immunoblotting / methods Light Microscopy, Confocal Mitochondria / enzymology* Mutagenesis, Insertional Open Reading Frames Plant Leaves / growth & development Plant Leaves / metabolism Plant Roots / growth & development Plant Roots / metabolism Proline / metabolism Protoplasts / metabolism Recombinant Fusion Proteins Saccharomyces cerevisiae / enzymology Saccharomyces cerevisiae / genetics Seedlings / growth & development Seedlings / metabolism Tobacco / genetics Tobacco / metabolism gamma-Aminobutyric Acid / metabolism*
IF 6.141
Times Cited 100
Arabidopsis / Cultured plant cells, genes pda08090