Characterization of a K+-ATPase from Lactobacillus helveticus ATCC 15009

Cristina Solari, Isabella Panfoli, Alessandro Morelli, Denise Cassandrini, Piersandro Cocconcelli, Lorenzo Morelli

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Lactobacillus helveticus ATCC 15009 (wild-type) membrane preparations hydrolyzed Mg2+-ATP as a function of K+ concentration (2-200 mM). Mg2+-ATP hydrolysis by L. helveticus membranes was strongly inhibited in the absence of exogenous K+, while it amounted to 6 nmol ATP hydrolyzed min-1 (mg membrane protein)-1 at 50 mM KCl (saturating conditions) and pH 7.2. The K+-dependent ATPase of L. helveticus displayed a relatively high affinity for potassium ions (K(m) = 800 μM) and was not affected by pretreatment of membranes with N,N' -dicyclohexylcarbodiimide. Membrane preparations were subjected to hypotonic shock to obtain a maximum yield of open profiles. The formation of a maximum level of enzyme-phosphate complex with a molecular mass of approximately 82 kDa was induced upon treatment of L. helveticus membrane preparations with low concentrations of [γ-32P]]ATP in the presence of K+ and La3+ ions and was visualized by acidic SDS-PAGE. It was concluded that L. helveticus membranes contain an inwardly directed K+ pump whose presence is discussed in terms of its putative role in cytoplasmic pH regulation.

Original languageEnglish
Pages (from-to)205-209
Number of pages5
JournalArchives of Microbiology
Issue number3
Publication statusPublished - 1997


  • 2,3-Butanedione
  • Enzyme-phosphate complex
  • K-ATPase
  • Lactobacilli
  • Potassium pump

ASJC Scopus subject areas

  • Microbiology


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