title: The chloroplast Ndh complex mediates the dark reduction of the plastoquinone pool in response to heat stress in tobacco leaves.
abstract: We have examined the effects of heat stress on electron transfer in the thylakoid membrane of an engineered plastid ndh deletion mutant, delta1, incapable of performing the Ndh-mediated reduction of the plastoquinone pool in the chloroplast. Upon heat stress in the dark, the rate of PSII-independent reduction of PSI after subsequent illumination by far-red light is dramatically enhanced in both delta1 and a wild-type control plant (WT). In contrast, in the dark, only the WT shows an increase in the reduction state of the plastoquinone pool. We conclude that the heat stress-induced reduction of the intersystem electron transport chain can be mediated by Ndh-independent pathways in the light but that in the dark the dominant pathway for reduction of the plastoquinone pool is catalysed by the Ndh complex. Our results therefore demonstrate a functional role for the Ndh complex in the dark.
authors.affiliation: Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, UK.
authors.forename: L A
authors.initials: LA
authors.lastname: Sazanov
authors.forename: P A
authors.initials: PA
authors.lastname: Burrows
authors.forename: P J
authors.initials: PJ
authors.lastname: Nixon
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism*; D018882:Heat Stress Disorders / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D010947:Plants, Toxic; D010971:Plastoquinone / Q000378:metabolism*; D014026:Nicotiana
chemical_list: D010940:Plant Proteins; D002734:Chlorophyll; D010971:Plastoquinone