title: Two proteins homologous to PsbQ are novel subunits of the chloroplast NAD(P)H dehydrogenase.
abstract: The PsbQ-like (PQL) proteins 1 and 2, previously shown to be located in the thylakoid lumen of Arabidopsis thaliana, are homologous to PSII oxygen-evolving complex protein PsbQ. Nevertheless, pql mutants showed no defects in PSII but instead the activity of the chloroplast NAD(P)H dehydrogenease (NDH) complex was severely impaired. In line with this observation, the NDH subunits were low in abundance in pql mutants, and, conversely, ndh mutants strongly down-regulated the accumulation of the PQL proteins. In addition, the PQL2 protein was up-regulated in mutant plants deficient in the PSI complex or the thylakoid membrane-bound ferredoxin-NADP(+) oxidoreductase, whereas in pql mutants the PSI complex was slightly up-regulated. Taken together, the two PQL proteins are shown to be novel subunits of the lumenal protuberance of the NDH complex.
authors.affiliation: Department of Biochemistry and Food Chemistry, Molecular Plant Biology, FI-20014 University of Turku, Finland.
authors.forename: Marjaana
authors.initials: M
authors.lastname: Suorsa
authors.forename: Sari
authors.initials: S
authors.lastname: Sirpiö
authors.forename: Virpi
authors.initials: V
authors.lastname: Paakkarinen
authors.forename: Nilima
authors.initials: N
authors.lastname: Kumari
authors.forename: Maija
authors.initials: M
authors.lastname: Holmström
authors.forename: Eva-Mari
authors.initials: EM
authors.lastname: Aro
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D009252:NADPH Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000378:metabolism; D020524:Thylakoids / Q000201:enzymology*
chemical_list: D029681:Arabidopsis Proteins; D045332:Photosystem II Protein Complex; D009252:NADPH Dehydrogenase