Expression of a yeast acetyl CoA hydrolase in the mitochondrion of tobacco plants inhibits growth and restricts photosynthesis

Plant Mol Biol. 2004 Jul;55(5):645-62. doi: 10.1007/s11103-004-1557-4.

Abstract

Acetyl Coenzyme A (acetyl CoA) is required in the mitochondria to fuel the operation of the Krebs cycle and within the cytosolic, peroxisomal and plastidial compartments wherein it acts as the immediate precursor for a wide range of anabolic functions. Since this metabolite is impermeable to membranes it follows that discrete pathways both for its synthesis and for its utilization must be present in each of these organelles and that the size of the various compartmented pools are independently regulated. To determine the specific role of acetyl CoA in the mitochondria we exploited a transgenic approach to introduce a yeast acetyl CoA hydrolase (EC 3.1.2.1.) into this compartment in tobacco plants. Despite the facts that the introduced enzyme was correctly targeted and that there were marked reductions in the levels of citrate and malate and an increase in the acetate content of the transformants, the transgenic plants surprisingly exhibited increased acetyl CoA levels. The lines were further characterised by a severe growth retardation, abnormal leaf colouration and a dramatic reduction in photosynthetic activity correlated with a marked reduction in the levels of transcripts of photosynthesis and in the content of photosynthetic pigments. The altered rate of photosynthesis in the transgenics was also reflected by a modified carbon partitioning in leaves of these lines, however, further studies revealed that this was most likely caused by a decreased source to sink transport of carbohydrate. In summary these results suggest that the content of acetyl CoA is under tight control and that alterations in the level of this central metabolite have severe metabolic and developmental consequences in tobacco.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetate-CoA Ligase / genetics
  • Acetyl-CoA Hydrolase / genetics*
  • Acetyl-CoA Hydrolase / metabolism
  • Biological Transport
  • Carbohydrate Metabolism
  • Gene Expression Regulation, Enzymologic*
  • Gene Expression Regulation, Plant
  • Glutamic Acid / metabolism
  • Glutamine / metabolism
  • Glyceric Acids / metabolism
  • Glycine / metabolism
  • Intramolecular Transferases / genetics
  • Mitochondria / enzymology*
  • Phenotype
  • Photosynthesis / genetics
  • Photosynthesis / physiology*
  • Plant Leaves / genetics
  • Plant Leaves / metabolism
  • Plants, Genetically Modified
  • Pyruvate Dehydrogenase Complex / metabolism
  • RNA, Plant / genetics
  • RNA, Plant / metabolism
  • Ribulose-Bisphosphate Carboxylase / genetics
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism
  • Starch / metabolism
  • Sucrose / metabolism
  • Time Factors
  • Tobacco / genetics*
  • Tobacco / growth & development
  • Tobacco / physiology
  • Transcription, Genetic / genetics
  • Uridine Diphosphate Glucose / metabolism

Substances

  • Glyceric Acids
  • Pyruvate Dehydrogenase Complex
  • RNA, Plant
  • Saccharomyces cerevisiae Proteins
  • Glutamine
  • Glutamic Acid
  • Sucrose
  • 3-phosphoglycerate
  • Starch
  • Acetyl-CoA Hydrolase
  • Ribulose-Bisphosphate Carboxylase
  • Intramolecular Transferases
  • glutamate-1-semialdehyde 2,1-aminomutase
  • Acetate-CoA Ligase
  • Glycine
  • Uridine Diphosphate Glucose