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Light induced photosynthetic electron transfer upon anaerobiosis in Chlamydomonas: Kinetics, electron sinks and setup of a fluorescence screen to identify new players
Godaux, Damien; Emonds-Alt, Barbara; Alric, Jean et al.
20121st international Young Algaeneers Symposium
 

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Keywords :
Chlamydomonas; photosynthesis; screening
Abstract :
[en] 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 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.
Research center :
Laboratoire de génétique des microorganismes
Disciplines :
Biochemistry, biophysics & molecular biology
Author, co-author :
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 :
15 June 2012
Event name :
1st international Young Algaeneers Symposium
Event organizer :
Wageningen University, Bioprocess engineering laboratory
Event place :
Wageningen, Netherlands
Event date :
from 14-06-2012 to 16-06-2012
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 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.
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
Commentary :
Présentation Orale de 20 minutes avec une scéance de questions-réponses de 10 minutes sur une partie des résultats obtenus lors de la deuxième année de ma thèse.
Available on ORBi :
since 25 June 2012

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