A novel gamma-hydroxybutyrate dehydrogenase: identification and expression of an Arabidopsis cDNA and potential role under oxygen deficiency.

Abstract

In plants, gamma-aminobutyrate (GABA), a non-protein amino acid, accumulates rapidly in response to a variety of abiotic stresses such as oxygen deficiency. Under normoxia, GABA is catabolized to succinic semialdehyde and then to succinate with the latter reaction being catalyzed by succinic semialdehyde dehydrogenase (SSADH). Complementation of an SSADH-deficient yeast mutant with an Arabidopsis cDNA library enabled the identification of a novel cDNA (designated as AtGH-BDH for Arabidopsis thaliana gamma-hydroxybutyrate dehydrogenase), which encodes a 289-amino acid polypeptide containing an NADP-binding domain. Constitutive expression of AtGHBDH in the mutant yeast enabled growth on 20 mm GABA and significantly enhanced the cellular concentrations of gamma-hydroxybutyrate, the product of the GHDBH reaction. These data confirm that the cDNA encodes a polypeptide with GHBDH activity. Arabidopsis plants subjected to flooding-induced oxygen deficiency for up to 4 h possessed elevated concentrations of gamma-hydroxybutyrate as well as GABA and alanine. RNA expression analysis revealed that GHBDH transcription was not up-regulated by oxygen deficiency. These findings suggest that GHBDH activity is regulated by the supply of succinic semialdehyde or by redox balance. It is proposed that GHBDH and SSADH activities in plants are regulated in a complementary fashion and that GHBDH and gamma-hydroxybutyrate function in oxidative stress tolerance.

• Authors: Kevin E Breitkreuz, Wendy L Allan, Owen R Van Cauwenberghe, Cornelis Jakobs, Driss Talibi, Bruno Andre, Barry J Shelp
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 278 Issue 42 Pg. 41552-6 (Oct 17 2003) ISSN: 0021-9258 [Print] United States
• PMID: 12882961 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• DNA, Complementary
• Peptides
• Plant Proteins
• gamma-Aminobutyric Acid
• Hydroxybutyrate Dehydrogenase
• 4-hydroxybutyrate dehydrogenase
• Aldehyde Oxidoreductases
• Succinate-Semialdehyde Dehydrogenase
• Alanine
• Oxygen

Topics

• Alanine (chemistry)
• Aldehyde Oxidoreductases (metabolism)
• Amino Acid Sequence
• Arabidopsis (enzymology)
• DNA, Complementary (metabolism)
• Genetic Complementation Test
• Hydroxybutyrate Dehydrogenase (chemistry, genetics, metabolism)
• Models, Biological
• Molecular Sequence Data
• Oxidation-Reduction
• Oxidative Stress
• Oxygen (metabolism)
• Peptides (chemistry)
• Plant Proteins (metabolism)
• Sequence Homology, Amino Acid
• Succinate-Semialdehyde Dehydrogenase
• Time Factors
• Up-Regulation
• gamma-Aminobutyric Acid (metabolism)