title: Isolation and characterization of a neomycin-resistant mutant of Methanobacterium thermoautotrophicum with a lesion in Na+-translocating ATPase (synthase).
abstract: A mutant of Methanobacterium thermoautotrophicum with a lesion in membrane Na+-translocating ATPase (synthase) was isolated. The total ATPase activity in permeabilized cells of this mutant was elevated three-fold as compared with the wild-type strain. In contrast to wild-type cells, mutant ATPase was neither inhibited by DCCD nor stimulated by Na+ ions. The methane formation orate of the mutant cells at pH 7.5 under non-growing conditions was nearly twice that of the wild-type strain and was stimulated by sodium ions. On the other hand, the ATP synthesis driven by methanogenesis under the same conditions was lower that of the wild-type under the same conditions, and contrary to the wild-type was not stimulated by Na+ ions. ATP synthesis driven by a potassium diffusion potential in the presence of sodium ions was markedly diminished in the mutant cells. The membrane potential values of the wild-type and the mutant cells in the presence of 10 mM NaCl at pH 7.0 were comparable at energized conditions (-223 mV and -230 mV respectively). The Mg2+-dependent ATPase activity of the 10(5) x g supernatant of broken cells from the mutant cells was 30% higher than in the wild-type. On the other hand, two bands with Mg2+-dependent ATPase activity were identified by native PAGE in this fraction in both wild-type as well as in mutant. These data suggest that the binding of Na+-translocating ATPase (synthase) to the membrane spanning part is changed in the mutant strain.
authors.affiliation: Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, Ivanka pri Dunaji, Slovak Republic. smigan@ubgz.savba.sk
authors.forename: P
authors.initials: P
authors.lastname: Smigán
authors.forename: P
authors.initials: P
authors.lastname: Polák
authors.forename: A
authors.initials: A
authors.lastname: Majernik
authors.forename: M
authors.initials: M
authors.lastname: Greksák
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D027682:Cation Transport Proteins; D002462:Cell Membrane / Q000201:enzymology; D002463:Cell Membrane Permeability; D004024:Dicyclohexylcarbodiimide / Q000494:pharmacology; D004352:Drug Resistance, Microbial / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000378:metabolism; D017014:Methanobacterium / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D009154:Mutation; D009355:Neomycin / Q000494:pharmacology*; D012964:Sodium / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D027682:Cation Transport Proteins; D004024:Dicyclohexylcarbodiimide; D000255:Adenosine Triphosphate; D012964:Sodium; D000251:Adenosine Triphosphatases; C021838:sodium-translocating ATPase; D009355:Neomycin; D008697:Methane