Abstract
An amiloride-resistant mutant with diminished Na+/H+ antiporter activity was isolated fromMethanothermobacter thermoautotrophicus. To define the protein basis of amiloride resistance, the composition of membrane-associated proteins was partially characterized and compared with that of the wild type strain. An abundant 670-kDa membrane-associated protein that was present only in the mutant strain was analyzed by MALDI-TOF MS and identified as a coenzyme F420-reducing hydrogenase. The amiloride resistance was not accompanied by changes in protein size or changes in the level of subunits A or B of the A1Ao-type ATP synthase; on the other hand, the SDS-PAGE patterns of the chloroform-methanol extract of membranes from both strains were different. Two bands with calculated molecular mass 16 and 11 kDa were identified as MtrD and AtpK, respectively. The observed over-expression of a 22.7-kDa protein in the mutant cells may represent the multimeric form of the MtrD subunit. These results show that the impairment of the Na+/H+ antiporter system in the amiloride-resistant mutant ofMethanothermobacter thermoautotrophicus is accompanied by only small changes in a few membrane-associated proteins.
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This work was supported in part by a research grants (VEGA project 2/3047/23) of theSlovak Academy of Sciences and theSlovak Science and Technology Assistance Agency (APVT 51-024 904).
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Šurín, S., Čuboňová, L., Majerník, A.I. et al. Amiloride resistance in the methanoarcheonMethanothermobacter thermoautotrophicus: Characterization of membrane-associated proteins. Folia Microbiol 51, 313–316 (2006). https://doi.org/10.1007/BF02931822
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DOI: https://doi.org/10.1007/BF02931822