Channel-mediated potassium uptake in Helicobacter pylori is essential for gastric colonization.
To date, the biological role of prokaryotic K(+) channels remains unknown. Helicobacter pylori contains a gene encoding a putative K(+) channel (HpKchA) of the two-transmembrane RCK (regulation of K(+) conductance) domain family, but lacks known bacterial K(+) uptake systems. A H. pylori DeltahpKchA mutant presented a strong growth defect at low K(+) concentration, which was compensated by KCl addition. The role of the separate RCK domain was investigated in H. pylori by mutagenesis of its internal start codon, which led to a K(+)-dependent intermediate growth phenotype, consistent with RCK activating channel function. Tagging HpKchA C-terminally, we detected a 1:1 stoichiometry of the full-length HpKchA and the separate RCK domain. We constructed single amino-acid exchanges within the unusual selectivity filter of HpKchA (ATGFGA) in H. pylori and observed complete loss (G74A), a slight defect (G76A or F75G) or wild-type (A77D) channel function. HpKchA was essential for colonization of the murine stomach. These data show, for the first time, a biological function for a prokaryotic K(+) channel, as a K(+) uptake system, essential for the persistence of H. pylori in the gastric environment.
Stingl
Kerstin
K
Institut Pasteur, Unité de Pathogénie bactérienne des muqueuses, Paris, France. k.stingl@web.de
Brandt
Sonja
S
Uhlemann
Eva-Maria
EM
Schmid
Roland
R
Altendorf
Karlheinz
K
Zeilinger
Carsten
C
Ecobichon
Chantal
C
Labigne
Agnès
A
Bakker
Evert P
EP
de Reuse
Hilde
H
D000595:Amino Acid Sequence; D000818:Animals; D018387:Codon, Initiator; D003593:Cytoplasm / Q000378:metabolism; D005753:Gastric Mucosa / Q000382:microbiology*; D016480:Helicobacter pylori / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D011188:Potassium / Q000737:chemistry / Q000493:pharmacokinetics*; D015221:Potassium Channels / Q000737:chemistry* / Q000502:physiology; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D018387:Codon, Initiator; C517797:KchA protein, Helicobacter pylori; D015221:Potassium Channels; D011188:Potassium