title: Isolation of Enterococcus hirae mutant deficient in low-affinity potassium uptake at alkaline pH.
abstract: We here isolated an Enterococcus hirae mutant unable to grow well at pH 10. The influx rate calculated from steady-state 42K+/K+ exchange and the intracellular K+ concentration of the mutant were reduced to 53 and 55% of those of the wild-type, respectively. The activities of two high-affinity K+ uptake systems, KtrI and KtrII, were normal in the mutant, but the kinetics of net K+ uptake at pH 10 indicated that a low-affinity K+ uptake with a Km of about 20 mM (Kawano, M, Abuki, R, Igarashi, K, Kakinuma, Y. (2001) Arch. Microbiol. 175: 41-45), which were seen in the wild-type, was deficient in this mutant.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Kawano
authors.forename: Kazuei
authors.initials: K
authors.lastname: Igarashi
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Kakinuma
mesh_terms: D000468:Alkalies; D003470:Culture Media; D016983:Enterococcus / Q000235:genetics* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009154:Mutation / Q000235:genetics*; D011188:Potassium / Q000378:metabolism*; D011197:Potassium Radioisotopes
chemical_list: D000468:Alkalies; D003470:Culture Media; D011197:Potassium Radioisotopes; D011188:Potassium