title: Isolation and characterization of an amiloride-resistant mutant of Methanothermobacter thermautotrophicus possessing a defective Na+/H+ antiport.
abstract: A spontaneous mutant of Methanothermobacter thermautotrophicus resistant to the Na+/H+ antiporter inhibitor amiloride was isolated. The Na+/H+ exchanger activity in the mutant cells was remarkably decreased in comparison with wild-type cells. Methanogenesis rates in the mutant strain were higher than wild-type cells and resistant to the inhibitory effect of 2 mM amiloride. In contrast, methanogenesis in wild-type cells was completely inhibited by the same amiloride concentration. ATP synthesis driven by methanogenic electron transport or by an electrogenic potassium efflux in the presence of sodium ions was significantly enhanced in the mutant cells. ATP synthesis driven by potassium diffusion potential was profoundly inhibited in wild-type cells by the presence of uncoupler 3,3',4',5- tetrachlorosalicylanilide and sodium ions, whereas c. 50% inhibition was observed in the mutant cells under the same conditions.
authors.affiliation: Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Ivanka pri Dunaji, Slovakia.
authors.forename: Stanislav
authors.initials: S
authors.lastname: Surín
authors.forename: L'ubomíra
authors.initials: L
authors.lastname: Cubonová
authors.forename: Alan I
authors.initials: AI
authors.lastname: Majerník
authors.forename: Paul
authors.initials: P
authors.lastname: McDermott
authors.forename: James P J
authors.initials: JP
authors.lastname: Chong
authors.forename: Peter
authors.initials: P
authors.lastname: Smigán
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000584:Amiloride / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D008697:Methane / Q000378:metabolism; D017013:Methanobacteriaceae / Q000145:classification* / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification; D009154:Mutation; D010641:Phenotype; D026941:Sodium Channel Blockers / Q000494:pharmacology*; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors*
chemical_list: D026941:Sodium Channel Blockers; D017923:Sodium-Hydrogen Exchangers; D000584:Amiloride; D000255:Adenosine Triphosphate; D008697:Methane