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J. Bacteriol., Mar 1997, 1714-1720, Vol 179, No. 5
A Das, DM Ivey and LG Ljungdahl
The proton-translocating F1F0 ATP synthase from Clostridium
thermoautotrophicum was solubilized from cholate-washed membranes with
Zwittergent 3-14 at 58 degrees C and purified in the presence of
octylglucoside by sucrose gradient centrifugation and ion-exchange
chromatography on a DEAE-5PW column. The purified enzyme hydrolyzed ATP at
a rate of 12.6 micromol min(-1) mg(-1) at 58 degrees C and pH 8.5. It was
composed of six different polypeptides with molecular masses of 60, 50, 32,
19, 17, and 8 kDa. These were identified as alpha, beta, gamma, delta,
epsilon, and c subunits, respectively, as their N- terminal amino acid
sequences matched the deduced N-terminal amino acid sequences of the
corresponding genes of the atp operon sequenced from Clostridium
thermoaceticum (GenBank accession no. U64318), demonstrating the close
similarity of the F1F0 complexes from C. thermoaceticum and C.
thermoautotrophicum. Four of these subunits, alpha, beta, gamma, and
epsilon, constituted the F1-ATPase purified from the latter bacterium. The
delta subunit could not be found in the purified F1 although it was present
in the F1F0 complex, indicating that the F0 moiety consisted of the delta
and the c subunits and lacked the a and b subunits found in many aerobic
bacteria. The c subunit was characterized as N,N'-dicyclohexylcarbodiimide
reactive. The F1F0 complex of C. thermoautotrophicum consisting of subunits
alpha, beta, gamma, delta, epsilon, and c was reconstituted with
phospholipids into proteoliposomes which had ATP-Pi exchange,
carbonylcyanide p- trifluoromethoxy-phenylhydrazone-stimulated ATPase, and
ATP-dependent proton-pumping activities. Immunoblot analyses of the
subunits of ATP synthases from C. thermoautotrophicum, C. thermoaceticum,
and Escherichia coli revealed antigenic similarities among the F1 subunits
from both clostridia and the beta subunit of F1 from E. coli.
Copyright © 1997, American Society for Microbiology
Purification and reconstitution into proteoliposomes of the F1F0 ATP synthase from the obligately anaerobic gram-positive bacterium Clostridium thermoautotrophicum
Department of Biochemistry and Molecular Biology, University of Georgia, Athens 30602, USA.
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