February 19, 2010 | David F. Coppedge

Molecular Highway Motor Comes into Focus

A beautiful new image of kinesin, a molecular machine that carries cargo on cellular highways, has been produced in greater detail than ever by a team at Berkeley and Brandeis Universities.  Science Daily published a picture and description of how kinesin works.  “Life’s smallest motor – a protein that shuttles cargo within cells and helps cells divide – does so by rocking up and down like a seesaw,” the article began.  The work is done using energy from ATP.
    Ken Downing described the motion: “We found that there is a pivot point, where the kinesin motor attaches to the microtubule, which acts like a fulcrum and causes kinesin to rock up and down like a seesaw as it moves along the microtubule.”  Kinesin is involved a numerous cell processes.  It’s one of the motor proteins that actually moves cargo on cellular highways.  The article said, “kinesin proteins motor along microtubules like trains on a railroad track, towing cargo to various locations within cells and assisting in cell division.”  Each rocking motion of the see-saw requires energy from ATP.
    Franck Fournio and Carolyn A. Moores, commenting on the findings for PNAS,1 described the motors as being fuel-efficient as macromotors need to be.  “Thus the cell’s nanomachines have evolved to use ATP only when they can couple it to essential work.”  The original paper by Sindelar and Downing in PNAS2 contains detailed model illustrations of how the seesaw motion links different parts of the machine to interact with structures on the microtubule.  All these interactions occur due to precisely-placed loops, linkers and pivots built out of the amino acids making up the protein parts of the machine.  Several domains of the machine undergo significant conformational changes during the motion.  Terms like “force generation” and “fulcrum” used in the paper indicate that these are true machines, just like those made by man, but on an almost unfathomably small scale – a few billionths of a meter in size.
    The authors did not describe how this machine could have evolved.  Fournio and Moores simply stated that kinesins “have evolved to” use ATP efficiently.  Sindelar and Downing said kinesin is a descendant of the myosin molecular motor family, with which it shares similarities.  They described myosin, however, as “its larger and more complex, ancient cousin,” suggesting that any evolution has been toward simplicity.

1.  Franck Fournio and Carolyn A. Moores, “ Proceedings of the National Academy of Sciences, www.pnas.org/cgi/doi/10.1073/pnas.0915158107.
2.  Sindelar, C. V., Downing, K. H., “An atomic-level mechanism for activation of the kinesin molecular motors,” Proceedings of the National Academy of Sciences, early edition, February 16, 2010, doi: 10.1073/pnas.0911208107.

Once again we see evolution assumed in passing but contributing nothing to the understanding of a wonder of nature.  This story is all about structural architecture, function, engineering, precision, efficiency – intelligent design.  Let’s cure scientists of their bad habit of assuming evolution when the evidence for design keeps coming into sharper focus.

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