title: PHOTOSYSTEM II PROTEIN33, a protein conserved in the plastid lineage, is associated with the chloroplast thylakoid membrane and provides stability to photosystem II supercomplexes in Arabidopsis.
abstract: Photosystem II (PSII) is a multiprotein complex that catalyzes the light-driven water-splitting reactions of oxygenic photosynthesis. Light absorption by PSII leads to the production of excited states and reactive oxygen species that can cause damage to this complex. Here, we describe Arabidopsis (Arabidopsis thaliana) At1g71500, which encodes a previously uncharacterized protein that is a PSII auxiliary core protein and hence is named PHOTOSYSTEM II PROTEIN33 (PSB33). We present evidence that PSB33 functions in the maintenance of PSII-light-harvesting complex II (LHCII) supercomplex organization. PSB33 encodes a protein with a chloroplast transit peptide and one transmembrane segment. In silico analysis of PSB33 revealed a light-harvesting complex-binding motif within the transmembrane segment and a large surface-exposed head domain. Biochemical analysis of PSII complexes further indicates that PSB33 is an integral membrane protein located in the vicinity of LHCII and the PSII CP43 reaction center protein. Phenotypic characterization of mutants lacking PSB33 revealed reduced amounts of PSII-LHCII supercomplexes, very low state transition, and a lower capacity for nonphotochemical quenching, leading to increased photosensitivity in the mutant plants under light stress. Taken together, these results suggest a role for PSB33 in regulating and optimizing photosynthesis in response to changing light levels.
authors.affiliation: Department of Chemistry and Biochemistry (R.F., C.E.B.-H., S.S.M.) and Institute for Genomics and Proteomics (S.S.M.), University of California, Los Angeles, California 90095;Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden (A.H., B.L.);Department of Chemistry, Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden (F.M.); andDepartment of Biochemistry and Molecular Biology and Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (R.L.L., B.L.).
authors.forename: Rikard
authors.initials: R
authors.lastname: Fristedt
authors.affiliation: Department of Chemistry and Biochemistry (R.F., C.E.B.-H., S.S.M.) and Institute for Genomics and Proteomics (S.S.M.), University of California, Los Angeles, California 90095;Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden (A.H., B.L.);Department of Chemistry, Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden (F.M.); andDepartment of Biochemistry and Molecular Biology and Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (R.L.L., B.L.).
authors.forename: Andrei
authors.initials: A
authors.lastname: Herdean
authors.affiliation: Department of Chemistry and Biochemistry (R.F., C.E.B.-H., S.S.M.) and Institute for Genomics and Proteomics (S.S.M.), University of California, Los Angeles, California 90095;Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden (A.H., B.L.);Department of Chemistry, Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden (F.M.); andDepartment of Biochemistry and Molecular Biology and Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (R.L.L., B.L.).
authors.forename: Crysten E
authors.initials: CE
authors.lastname: Blaby-Haas
authors.affiliation: Department of Chemistry and Biochemistry (R.F., C.E.B.-H., S.S.M.) and Institute for Genomics and Proteomics (S.S.M.), University of California, Los Angeles, California 90095;Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden (A.H., B.L.);Department of Chemistry, Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden (F.M.); andDepartment of Biochemistry and Molecular Biology and Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (R.L.L., B.L.).
authors.forename: Fikret
authors.initials: F
authors.lastname: Mamedov
authors.affiliation: Department of Chemistry and Biochemistry (R.F., C.E.B.-H., S.S.M.) and Institute for Genomics and Proteomics (S.S.M.), University of California, Los Angeles, California 90095;Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden (A.H., B.L.);Department of Chemistry, Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden (F.M.); andDepartment of Biochemistry and Molecular Biology and Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (R.L.L., B.L.).
authors.forename: Sabeeha S
authors.identifier: http://orcid.org/0000-0002-2594-509X
authors.initials: SS
authors.lastname: Merchant
authors.affiliation: Department of Chemistry and Biochemistry (R.F., C.E.B.-H., S.S.M.) and Institute for Genomics and Proteomics (S.S.M.), University of California, Los Angeles, California 90095;Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden (A.H., B.L.);Department of Chemistry, Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden (F.M.); andDepartment of Biochemistry and Molecular Biology and Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (R.L.L., B.L.).
authors.forename: Robert L
authors.identifier: http://orcid.org/0000-0001-6974-9587
authors.initials: RL
authors.lastname: Last
authors.affiliation: Department of Chemistry and Biochemistry (R.F., C.E.B.-H., S.S.M.) and Institute for Genomics and Proteomics (S.S.M.), University of California, Los Angeles, California 90095;Department of Biological and Environmental Sciences, University of Gothenburg, 405 30 Gothenburg, Sweden (A.H., B.L.);Department of Chemistry, Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden (F.M.); andDepartment of Biochemistry and Molecular Biology and Department of Plant Biology, Michigan State University, East Lansing, Michigan 48824 (R.L.L., B.L.) bjorn.lundin@gmail.com.
authors.forename: Björn
authors.initials: B
authors.lastname: Lundin
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D017124:Conserved Sequence; D005453:Fluorescence; D017343:Genes, Plant; D007425:Intracellular Membranes / Q000378:metabolism* / Q000528:radiation effects; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D055668:Photochemical Processes / Q000528:radiation effects; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D055550:Protein Stability / Q000528:radiation effects; D021381:Protein Transport / Q000528:radiation effects; D020539:Sequence Analysis, Protein; D013347:Subcellular Fractions / Q000378:metabolism / Q000528:radiation effects; D020524:Thylakoids / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; D045342:Light-Harvesting Protein Complexes; D008565:Membrane Proteins; D045332:Photosystem II Protein Complex; D002734:Chlorophyll