An Anaplerotic Role for Mitochondrial Carbonic Anhydrase in Chlamydomonas reinhardtii1
AUTOR(ES)
Giordano, Mario
FONTE
The American Society for Plant Biologists
RESUMO
Previous studies of the mitochondrial carbonic anhydrase (mtCA) of Chlamydomonas reinhardtii showed that expression of the two genes encoding this enzyme activity required photosynthetically active radiation and a low CO2 concentration. These studies suggested that the mtCA was involved in the inorganic carbon-concentrating mechanism. We have now shown that the expression of the mtCA at low CO2 concentrations decreases when the external NH4+ concentration decreases, to the point of being undetectable when NH4+ supply restricts the rate of photoautotrophic growth. The expression of mtCA can also be induced at supra-atmospheric partial pressure of CO2 by increasing the NH4+ concentration in the growth medium. Conditions that favor mtCA expression usually also stimulate anaplerosis. We therefore propose that the mtCA is involved in supplying HCO3- for anaplerotic assimilation catalyzed by phosphoenolpyruvate carboxylase, which provides C skeletons for N assimilation under some circumstances.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=181296Documentos Relacionados
- Identification of a New Chloroplast Carbonic Anhydrase in Chlamydomonas reinhardtii1
- Effect of CO2 Concentration on Protein Biosynthesis and Carbonic Anhydrase Expression in Chlamydomonas reinhardtii1
- Intracellular carbonic anhydrase of Chlamydomonas reinhardtii.
- Periplasmic Carbonic Anhydrase Structural Gene (Cah1) Mutant in Chlamydomonas reinhardtii 1
- CO2-Responsive Transcriptional Regulation of CAH1 Encoding Carbonic Anhydrase Is Mediated by Enhancer and Silencer Regions in Chlamydomonas reinhardtii1
