April 30, 2005 | David F. Coppedge

World’s Smallest Rotary Motors Coming Into Focus

Science April 29 had three articles on the ATP synthase rotary motors that inhabit all living cells.1,2,3  Using creative techniques of extreme microscopy and crystallography, research teams are beginning to get more focused images of the carousel-like rotating engines of both F-type and V-type motors.  (V-type enzymes pump ions into the cell to regulate acidity; see 2/24/2003 entry.  F-type ATP synthase enzymes produce ATP, the energy currency of the cell; see 09/18/2003 entry.)
    The rotors look like elegant circular rings of helical units arranged at angles to the axis.  From the side, they look like “concave barrel with a pronounced waist in the middle, and an inner septum that is probably filled with and electrically sealed by membrane lipids in vivo.”  Scientists are still trying to figure out how the ions get into the active-site pockets in the subunits of the ring, and how they create torque to make the carousel go round.  It may result from harnessing Brownian motion in a ratcheting manner that only allows rotation in one direction.  All the researchers seem surprised that the gear ratio is not an integer, but rather 10:3 in some species, and 11:3 or 14:3 in others; it may be necessary that these motors have a non-integer ratio between the bottom carousel and the top catalytic engine for torque generation and catalytic activity (see 08/10/2004 entry).  They are also beginning to understand the nature of the camshaft attached to the carousel that induces ATP production in the top.
  Whatever their mechanism, these little engines, only 12 nanometers tall, are effective.  The review by Junge and Nelson says these motors can generate an acidity of pH 2 in lemons and 250 millivolts of electricity in insect guts.  We humans also run on electricity.  The constant action of quadrillions of these tiny generators running day and night in our bodies keeps all our energy systems humming at about 116 watts (see 02/05/2003 story).
    In another molecular-motor story, Current Biology4 reported about how actin and myosin work during cell division to pinch the two daughter cells apart.  David R. Burgess in a review5 states, “Myosin II is the motor for cytokinesis, an event at the end of cell division during which the animal cell uses a contractile ring to pinch itself in half.  New and surprising research shows that myosin, either through light chain phosphorylation or through its ATPase activity, also plays an important role in both the assembly and disassembly of the actin contractile ring.”

1Wolfgang Junge and Nathan Nelson, “Structural Biology: Nature’s Rotary Electromotors,” Science Vol 308, Issue 5722, 642-644 , 29 April 2005, [DOI: 10.1126/science.1112617].
2Murata et al., “Structure of the Rotor of the V-Type Na+-ATPase from Enterococcus hirae,” Science, Vol 308, Issue 5722, 654-659, 29 April 2005, [DOI: 10.1126/science.1110064].
3Meier et al., “Structure of the Rotor Ring of F-Type Na+-ATPase from Ilyobacter tartaricus,” Science, Vol 308, Issue 5722, 659-662 , 29 April 2005, [DOI: 10.1126/science.1111199].
4E. D. Salmon, “Microtubules: A Ring for the Depolymerization Motor,” Current Biology, Volume 15, Issue 8, 26 April 2005, Pages R299-R302, doi:10.1016/j.cub.2005.04.005.
5David R. Burgess, “Cytokinesis: New roles for myosin,” Current Biology, Volume 15, Issue 8, 26 April 2005, Pages R310-R311, doi:10.1016/j.cub.2005.04.008.

None of these five papers mention evolution once, nor make any attempt to explain how the motors of life could have arisen by an unguided process of chance or natural law.  Murata’s paper says “Eukaryotic V-ATPases contain 13 different polypeptides.”  Since getting just one usable polypeptide (protein) is astronomically improbable (see online book), it is utterly out of the question to assume that the complete set of these specialized functional molecules could have arisen by chance.  Even getting a few of them would be useless; all of them have to be in the same place, at the same time, in the same arrangement, together simultaneously for the system to work.  ATP synthase is a classic example of an irreducibly complex system that defies evolutionary explanation.  Since even the simplest organisms depend on these motors for life, and since Charlie’s magic wand of natural selection cannot be used at this stage (see online book), we have here a convincing case for intelligent design.  Similarly, since the actin/myosin operation is essential for cell division (e.g., replication, an essential prerequisite for natural selection), evolutionists have only chance as an explanation for the origin of these exquisite molecular machines.  To any thinking person, that would be absurd.  The Kansas school board (see 04/29/2005 entry) should hold up the pictures of ATP synthase from these papers and challenge the Darwinists to explain how such complex systems at the beginning of life could ever have arisen by chance.

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