Physiological impact of intrinsic ADP inhibition of cyanobacterial FoF1 conferred by the inherent sequence inserted into the gammasubunit.
The F(o)F(1)-ATPase, which synthesizes ATP with a rotary motion, is highly regulated in vivo in order to function efficiently, although there remains a limited understanding of the physiological significance of this regulation. Compared with its bacterial and mitochondrial counterparts, the gamma subunit of cyanobacterial F(1), which makes up the central shaft of the motor enzyme, contains an additional inserted region. Although deletion of this region results in the acceleration of the rate of ATP hydrolysis, the functional significance of the region has not yet been determined. By analysis of rotation, we successfully determined that this region confers the ability to shift frequently into an ADP inhibition state; this is a highly conserved regulatory mechanism which prevents ATP synthase from carrying out the reverse reaction. We believe that the physiological significance of this increased likelihood of shifting into the ADP inhibition state allows the intracellular ATP levels to be maintained, which is especially critical for photosynthetic organisms.
Sunamura
Ei-Ichiro
E
Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuta 4259-R1-8, Midori-Ku, Yokohama 226-8503, Japan.
Konno
Hiroki
H
Imashimizu-Kobayashi
Mari
M
Sugano
Yasushi
Y
Hisabori
Toru
T
D000244:Adenosine Diphosphate / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000096:biosynthesis; D025222:Chloroplast Proton-Translocating ATPases / Q000378:metabolism*; D000458:Cyanobacteria / Q000201:enzymology* / Q000502:physiology; D016254:Mutagenesis, Insertional; D021122:Protein Subunits / Q000378:metabolism; D017384:Sequence Deletion
D021122:Protein Subunits; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D025222:Chloroplast Proton-Translocating ATPases