title: Control of Autophagy in Chlamydomonas Is Mediated through Redox-Dependent Inactivation of the ATG4 Protease.
abstract: Autophagy is a major catabolic pathway by which eukaryotic cells deliver unnecessary or damaged cytoplasmic material to the vacuole for its degradation and recycling in order to maintain cellular homeostasis. Control of autophagy has been associated with the production of reactive oxygen species in several organisms, including plants and algae, but the precise regulatory molecular mechanisms remain unclear. Here, we show that the ATG4 protease, an essential protein for autophagosome biogenesis, plays a central role for the redox regulation of autophagy in the model green alga Chlamydomonas reinhardtii Our results indicate that the activity of C. reinhardtii ATG4 is regulated by the formation of a single disulfide bond with a low redox potential that can be efficiently reduced by the NADPH/thioredoxin system. Moreover, we found that treatment of C. reinhardtii cells with norflurazon, an inhibitor of carotenoid biosynthesis that generates reactive oxygen species and triggers autophagy in this alga, promotes the oxidation and aggregation of ATG4. We propose that the activity of the ATG4 protease is finely regulated by the intracellular redox state, and it is inhibited under stress conditions to ensure lipidation of ATG8 and thus autophagy progression in C. reinhardtii.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Sevilla, Spain (M.E.P.-P., J.L.C.); and eperez@ibvf.csic.es.|Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France (S.D.L.) eperez@ibvf.csic.es.
authors.forename: María Esther
authors.identifier: 0000-0003-0779-6665
authors.initials: ME
authors.lastname: Pérez-Pérez
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Sevilla, Spain (M.E.P.-P., J.L.C.); and.|Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France (S.D.L.).
authors.forename: Stéphane D
authors.initials: SD
authors.lastname: Lemaire
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Sevilla, Spain (M.E.P.-P., J.L.C.); and.|Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR8226, Laboratoire de Biologie Moléculaire et Cellulaire des Eucaryotes, Institut de Biologie Physico-Chimique, 75005 Paris, France (S.D.L.).
authors.forename: José L
authors.identifier: 0000-0003-3514-1025
authors.initials: JL
authors.lastname: Crespo
mesh_terms: D001343:Autophagy / Q000528:radiation effects; D002696:Chlamydomonas / Q000166:cytology* / Q000201:enzymology* / Q000528:radiation effects; D017124:Conserved Sequence; D003545:Cysteine / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D004789:Enzyme Activation / Q000528:radiation effects; D008027:Light; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction / Q000528:radiation effects; D010940:Plant Proteins / Q000378:metabolism*; D066329:Protein Aggregates / Q000528:radiation effects; D055503:Protein Multimerization / Q000528:radiation effects; D012694:Serine / Q000235:genetics; D013312:Stress, Physiological / Q000528:radiation effects; D013329:Structure-Activity Relationship; D013879:Thioredoxins / Q000378:metabolism
chemical_list: D004220:Disulfides; D010940:Plant Proteins; D066329:Protein Aggregates; D012694:Serine; D013879:Thioredoxins; D009249:NADP; D003545:Cysteine