title: A thylakoid-located two-pore K+ channel controls photosynthetic light utilization in plants.
abstract: The size of the light-induced proton motive force (pmf) across the thylakoid membrane of chloroplasts is regulated in response to environmental stimuli. Here, we describe a component of the thylakoid membrane, the two-pore potassium (K(+)) channel TPK3, which modulates the composition of the pmf through ion counterbalancing. Recombinant TPK3 exhibited potassium-selective channel activity sensitive to Ca(2+) and H(+). In Arabidopsis plants, the channel is found in the thylakoid stromal lamellae. Arabidopsis plants silenced for the TPK3 gene display reduced growth and altered thylakoid membrane organization. This phenotype reflects an impaired capacity to generate a normal pmf, which results in reduced CO2 assimilation and deficient nonphotochemical dissipation of excess absorbed light. Thus, the TPK3 channel manages the pmf necessary to convert photochemical energy into physiological functions.
authors.affiliation: Department of Biology, University of Padua, viale Giuseppe Colombo 3, 35121 Padua, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Carraretto
authors.forename: Elide
authors.initials: E
authors.lastname: Formentin
authors.forename: Enrico
authors.initials: E
authors.lastname: Teardo
authors.forename: Vanessa
authors.initials: V
authors.lastname: Checchetto
authors.forename: Martino
authors.initials: M
authors.lastname: Tomizioli
authors.forename: Tomas
authors.initials: T
authors.lastname: Morosinotto
authors.forename: Giorgio Mario
authors.initials: GM
authors.lastname: Giacometti
authors.forename: Giovanni
authors.initials: G
authors.lastname: Finazzi
authors.forename: Ildikó
authors.initials: I
authors.lastname: Szabó
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D008027:Light; D010788:Photosynthesis; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D024683:Potassium Channels, Tandem Pore Domain / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D029681:Arabidopsis Proteins; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D011994:Recombinant Proteins; C584020:TPK3 protein, Arabidopsis