title: A novel potassium channel in photosynthetic cyanobacteria.
abstract: Elucidation of the structure-function relationship of a small number of prokaryotic ion channels characterized so far greatly contributed to our knowledge on basic mechanisms of ion conduction. We identified a new potassium channel (SynK) in the genome of the cyanobacterium Synechocystis sp. PCC6803, a photosynthetic model organism. SynK, when expressed in a K(+)-uptake-system deficient E. coli strain, was able to recover growth of these organisms. The protein functions as a potassium selective ion channel when expressed in Chinese hamster ovary cells. The location of SynK in cyanobacteria in both thylakoid and plasmamembranes was revealed by immunogold electron microscopy and Western blotting of isolated membrane fractions. SynK seems to be conserved during evolution, giving rise to a TPK (two-pore K(+) channel) family member which is shown here to be located in the thylakoid membrane of Arabidopsis. Our work characterizes a novel cyanobacterial potassium channel and indicates the molecular nature of the first higher plant thylakoid cation channel, opening the way to functional studies.
authors.affiliation: Department of Biology, University of Padova, Padova, Italy.
authors.forename: Manuela
authors.initials: M
authors.lastname: Zanetti
authors.forename: Enrico
authors.initials: E
authors.lastname: Teardo
authors.forename: Nicoletta
authors.initials: N
authors.lastname: La Rocca
authors.forename: Lalu
authors.initials: L
authors.lastname: Zulkifli
authors.forename: Vanessa
authors.initials: V
authors.lastname: Checchetto
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Shijuku
authors.forename: Yuki
authors.initials: Y
authors.lastname: Sato
authors.forename: Giorgio Mario
authors.initials: GM
authors.lastname: Giacometti
authors.forename: Noboyuki
authors.initials: N
authors.lastname: Uozumi
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Bergantino
authors.forename: Ildikò
authors.initials: I
authors.lastname: Szabò
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics; D003001:Cloning, Molecular; D000458:Cyanobacteria / Q000737:chemistry / Q000235:genetics; D019143:Evolution, Molecular; D010788:Photosynthesis; D015221:Potassium Channels / Q000032:analysis* / Q000235:genetics; D046939:Synechocystis / Q000737:chemistry* / Q000235:genetics; D020524:Thylakoids / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D015221:Potassium Channels
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