Unpublished conference/Abstract (Scientific congresses and symposiums)
Light-induced photosynthetic electron transfer upon anaerobiosis in Chlamydomonas : kinetics, electron sinks and setup of a fluorescence screen to identify new players.
Godaux, Damien ; Université de Liège - ULiège > Département des sciences de la vie > Génétique
Emonds-Alt, Barbara ; Université de Liège - ULiège > Département des sciences de la vie > Génétique
alric, Jean
Ghysels, Bart ; Université de Liège - ULiège > Labo de Bioénergétique
Remacle, Claire ; Université de Liège - ULiège > Département des sciences de la vie > Génétique
Cardol, Pierre ; Université de Liège - ULiège > Département des sciences de la vie > Génétique
Language :
English
Title :
Light-induced photosynthetic electron transfer upon anaerobiosis in Chlamydomonas : kinetics, electron sinks and setup of a fluorescence screen to identify new players.
Publication date :
06 June 2012
Event name :
15th Conference on the Cell & Molecular Biology of Chlamydomonas
Event place :
Potsdam, Germany
Event date :
du 5 au 10 juin 2012
Audience :
International
References of the abstract :
In Chlamydomonas reinhardtii, prolonged anaerobiosis leads to the expression of various fermentative pathways. Among them, oxygen-sensitive hydrogenases (hyd) catalyze the reduction of protons from reduced ferredoxin resulting in the production of molecular hydrogen. In this work, light-induced photosynthetic electron transfer after a prolonged dark-anaerobiosis period was studied by following the kinetics of chlorophyll fluorescence emission, P700 oxidation and proton-motive force formation and consumption during the first 3 seconds of illumination. We show that during the induction of photosynthesis, an hyd-dependent photosynthetic electron transfer operates at a maximal rate of 110 electrons per photosystem per second, that is about half the one measured in aerobiosis. The implication in this process of components of the linear, cyclic and chlororespiratory electron transfer pathways, as well as of various electron sinks, are investigated thanks to the availability of mutants. In a next step, we screen an insertional mutant library (~3000 clones) on the basis of the fluorescence induction kinetics upon a shift from dark-anaerobiosis to light. Five mutants display the
signature of mutants deficient for NADPH:PQ oxidoreductase or hyd activities. In particular, one is defective for
hydrogenase HydG assembly factor. This mutant behaves exactly has the hydEF mutant, thus confirming that in vivo both the assembly factors are required for an efficient hydrogenase activity.
