|
Author
|
Topic: Nature's Rotary Electromotors
|
Moderator
Administrator
Member # 1
|
posted 18. July 2005 15:54
Science April 29
Nature's Rotary Electromotors
Wolfgang Junge and Nathan Nelson
Molecular motors abound in the cell. Myosin motors power muscle contraction, kinesin motors move vesicles from one end of the cell to the other, and the ribosome processes along RNA. These linearly operating molecular motors are all powered by cleavage of the universal "fuel" molecule ATP (adenosine 5'-triphosphate). The ATP synthase (or F-ATPase), which produces ATP, is a fine example of one of nature's rotary motors. F-ATPase consists of two coupled motors, one electrically driven and the other chemically driven. There are several types of rotary motors, but only three are electrically driven: the F0-portion of the F-type ATPase, the V0-portion of V-type ATPases, and the flagellar motor of bacteria. The first two obey similar construction principles, whereas the bacterial flagellar motor is quite different. But all three types of rotary motor contain a central, ion-binding rotor ring that is embedded in the respective coupling membrane of the cell. The first high-resolution crystal structures of this ring are now revealed by Meier et al. on page 659 (1) and Murata et al. on page 654 (2) of this issue. Meier and colleagues report the structure at 0.24-nm resolution of the c ring of the F-type Na+-ATPase from Ilyobacter tartaricus (1). Meanwhile, Murata and co-workers present the structure at 0.21-nm resolution of the K ring of the V-type Na+-ATPase from the bacterium Enterococcus hirae (2). Some of the newly revealed properties are in keeping with current mechanistic models, whereas others defy previous postulates.
IP: Logged
|
|
|
|
David L. Hagen
Member
Member # 323
|
posted 16. August 2005 19:03
Cells made to haul tiny cargoes
George Whitesides and Douglas Weibel of Harvard University have attached a polystyrene bead to green algae cell and used a high/low light intensity gradient to direct the cell’s movement. They expect that cells could be harnessed to perform micro-scale mechanical work.
See Proc. National Academy of Sciences, 2005 reported by BBC.
http://news.bbc.co.uk/2/hi/science/nature/4156282.stm
IP: Logged
|
|
|
Printer-friendly view of this topic