title: The thylakoid protease Deg2 is involved in stress-related degradation of the photosystem II light-harvesting protein Lhcb6 in Arabidopsis thaliana.
abstract: • The thylakoid protease Deg2 is a serine-type protease peripherally attached to the stromal side of the thylakoid membrane. Given the lack of knowledge concerning its function, two T-DNA insertion lines devoid of Deg2 were prepared to study the functional importance of this protease in Arabidopsis thaliana. • The phenotypic appearance of deg2 mutants was studied using a combination of stereo and transmission electron microscopy, and short-stress-mediated degradation of apoproteins of minor light-harvesting antennae of photosystem II (PSII) was analysed by immunoblotting in the mutants in comparison with wild-type plants. • Deg2 repression produced a phenotype in which reduced leaf area and modified chloroplast ultrastructure of older leaves were the most prominent features. In contrast to the wild type, the chloroplasts of second-whorl leaves of 4-wk-old deg2 mutants did not display features typical of the early senescence phase, such as undulation of the chloroplast envelope and thylakoids. The ability to degrade the photosystem II light-harvesting protein Lhcb6 apoprotein in response to brief high-salt, wounding, high-temperature and high-irradiance stress was demonstrated to be impaired in deg2 mutants. • Our results suggest that Deg2 is required for normal plant development, including the chloroplast life cycle, and has an important function in the degradation of Lhcb6 in response to short-duration stresses.
authors.affiliation: Department of Plant Physiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, ul. Umultowska 89, 61-614 Poznań, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Luciński
authors.affiliation: Department of Biotechnology, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, ul. Umultowska 89, 61-614 Poznań, Poland.
authors.forename: Lucyna
authors.initials: L
authors.lastname: Misztal
authors.affiliation: Laboratory of Electron and Confocal Microscopy, Faculty of Biology, Adam Mickiewicz University, ul. Umultowska 89, 61-614 Poznań, Poland.
authors.forename: Sławomir
authors.initials: S
authors.lastname: Samardakiewicz
authors.affiliation: Department of Plant Physiology, Institute of Experimental Biology, Faculty of Biology, Adam Mickiewicz University, ul. Umultowska 89, 61-614 Poznań, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Jackowski
mesh_terms: D001059:Apoproteins / Q000378:metabolism; D007611:Aprotinin / Q000494:pharmacology; D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000378:metabolism*; D061146:Chlorophyll Binding Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D015151:Immunoblotting; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D016254:Mutagenesis, Insertional / Q000187:drug effects / Q000235:genetics; D010641:Phenotype; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D059748:Proteolysis / Q000187:drug effects; D012697:Serine Endopeptidases / Q000378:metabolism*; D013312:Stress, Physiological / Q000187:drug effects; D020524:Thylakoids / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure
chemical_list: D001059:Apoproteins; D029681:Arabidopsis Proteins; D061146:Chlorophyll Binding Proteins; D004269:DNA, Bacterial; C529795:Lhcb6 protein, Arabidopsis; D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; C036483:T-DNA; D007611:Aprotinin; C516589:Deg2 protein, Arabidopsis; D012697:Serine Endopeptidases