F(0) of ATP synthase is a rotary proton channel. Obligatory coupling of proton translocation with rotation of c-subunit ring.
Coupling of proton flow and rotation in the F(0) motor of ATP synthase was investigated using the thermophilic Bacillus PS3 enzyme expressed functionally in Escherichia coli cells. Cysteine residues introduced into the N-terminal regions of subunits b and c of ATP synthase (bL2C/cS2C) were readily oxidized by treating the expressing cells with CuCl(2) to form predominantly a b-c cross-link with b-b and c-c cross-links being minor products. The oxidized ATP synthases, either in the inverted membrane vesicles or in the reconstituted proteoliposomes, showed drastically decreased proton pumping and ATPase activities compared with the reduced ones. Also, the oxidized F(0), either in the F(1)-stripped inverted vesicles or in the reconstituted F(0)-proteoliposomes, hardly mediated passive proton translocation through F(0). Careful analysis using single mutants (bL2C or cS2C) as controls indicated that the b-c cross-link was responsible for these defects. Thus, rotation of the c-oligomer ring relative to subunit b is obligatory for proton translocation; if there is no rotation of the c-ring there is no proton flow through F(0).
Suzuki
Toshiharu
T
Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259, Yokohama 226-8503, Japan.
Ueno
Hiroshi
H
Mitome
Noriyo
N
Suzuki
Junko
J
Yoshida
Masasuke
M
D001407:Bacillus / Q000201:enzymology*; D001483:Base Sequence; D017931:DNA Primers; D017136:Ion Transport; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011522:Protons; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism
D017931:DNA Primers; D011522:Protons; D011994:Recombinant Proteins; D006180:Proton-Translocating ATPases