P. Smigan et al., THE PRESENCE OF H-TRANSLOCATING ATPASES IN METHANOBACTERIUM-THERMOAUTOTROPHICUM AND THEIR POSSIBLE FUNCTION UNDER ALKALINE CONDITIONS( AND NA+), FEBS letters, 371(2), 1995, pp. 119-122
Two ATPases with different apparent molecular masses of approx, 500 kD
a and 400 kDa were identified in the EDTA extract of the cell membrane
s of Methanobacterium thermoautotrophicum. Western blotting with polyc
lonal antiserum reactive with beta-subunit of mitochondrial ATPase fro
m rat liver and yeast was used for further analysis of these ATPases.
A strong crossreactivity with a single protein band with an apparent m
olecular weight of about 53 kDa (similar to beta-subunit of F-type ATP
ase from other sources) was found in protein extracts of whole cells o
f Methanobacterium thermoautotrophicum strains Delta H and Marburg, as
well as of Methanospirillum hungatei. This indicates the presence of
F-type ATPase in methanogens, ATP synthesis driven by membrane potenti
al which was generated by artificially-imposed Delta pH in the presenc
e of protonophorous uncoupler and sodium ions was stimulated by bafilo
mycin A(1), an inhibitor of V- and A-type ATPases, as well as by harma
line, an inhibitor of Na+/H+ antiporter. These results indicate that c
ells of Methanobacterium thermoautotrophicum strain Delta H contain th
e F-type ATP synthase which is Na+-translocating in addition to V- or
A-type ATP synthase which is H+-translocating.