Proteomic and functional characterization of a Chlamydomonas reinhardtii mutant lacking the mitochondrial alternative oxidase 1.
ABSTRACT In the present work, we have isolated by RNA interference and characterized at the functional and the proteomic levels a Chlamydomonas reinhardtii strain devoid of the mitochondrial alternative oxidase 1 (AOX1). The AOX1-deficient strain displays a remarkable doubling of the cell volume and biomass without alteration of the generation time or change in total respiratory rate, with a significantly higher ROS production. To identify the molecular adaptation underlying these observations, we have carried out a comparative study of both the mitochondrial and the cellular soluble proteomes. Our results indicate a strong up-regulation of the ROS scavenging systems and important quantitative modifications of proteins involved in the primary metabolism, namely an increase of enzymes involved in anabolic pathways and a concomitant general down-regulation of enzymes of the main catabolic pathways.
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ABSTRACT: The metabolism of microalgae is so flexible that it is not an easy task to give a comprehensive description of the interplay between the various metabolic pathways. There are however constraints that govern central carbon metabolism in Chlamydomonas that are revealed by the compartmentalization and regulation of the pathways and their relation to key cellular processes such as cell motility, division, carbon uptake and partitioning, external and internal rhythms and nutrient stress. Both photosynthetic and mitochondrial electron transfer provide energy for metabolic processes and how energy transfer impacts metabolism and vice versa is a means of exploring the regulation and function of these pathways. A key example is the specific chloroplast localization of glycolysis/gluconeogenesis and how it impacts the redox poise and ATP budget of the plastid in the dark. To compare starch and lipids as carbon reserves, their value can be calculated in terms of NAD(P)H and ATP. As microalgae are now considered as a potential renewable feedstock, we examine current work on the subject and also explore the possibility of rerouting metabolism towards lipid production.Eukaryotic Cell 03/2013; · 3.59 Impact Factor