All living organisms maintain the functions required for life by using the energy released by the hydrolysis of adenosine triphosphate (ATP). Consequently, elucidating the mechanisms by which ATP-hydrolyzing enzymes function is important for our understanding of the fundamental processes of life.
V-ATPase is an ATP hydrolyzing enzyme that consists of a water-soluble V1 moiety and cell membrane-embedded Vo moiety, and controls ion concentration across the cell membrane. V1 is one of the smallest rotary molecular motors driven by ATP hydrolysis in nature. Previously, only the rotary motion of V1 from thermophilic bacteria Thermus thermophiles (TtV1) had been observed, and it had been reported that its rotary dynamics were different from another rotary molecular motor, the water-soluble F1 moiety of ATP synthase. Although the detailed comparison between V1 and F1 is important for a common understanding of the mechanisms of rotary molecular motors, the rotation of V1 other than TtV1 had not been observed.
The team of Lecturer Ryota Iino, Prof. Hiroyuki Noji, Yoshihiro Minagawa and Mayu Hara at the University of Tokyo Department of Applied Chemistry, Graduate School of Engineering, collaborating with Prof. Takeshi Murata at Chiba University and Prof. Hiroshi Ueno at Chuo University, has successfully observed the rotation of V1 from the intestinal bacterium Enterococcus hirae (EhV1) for the first time. The rotary dynamics of EhV1 were similar to that of the TtV1, and distinct from those of F1.
With this study, the difference in the rotary dynamics between V1 and F1 has been clarified. Further detailed comparison between V1 and F1 will reveal the common mechanisms of molecular rotary motors. This study was featured as the cover of the Journal of Biological Chemistry published on 8 November, 2013.
Source: University of Tokyo