BIOPHYSICAL THEORY AND MODELING |
Force and Flexibility of Flailing Myxobacteria
Charles W. Wolgemuth 1*
1 University of Connecticut Health Center
* To whom correspondence should be addressed. E-mail: cwolgemuth{at}uchc.edu.
Submitted on March 8, 2005
Revised on May 11, 2005
Accepted on 18 May 2005
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Abstract |
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Myxococcus xanthus is a common Gram-negative bacterium that moves by a process called gliding motility. In myxobacteria, two distinct mechanisms for gliding have been discovered. S-type motility requires the extension, attachment, and retraction of type IV pili. The other mechanism, designated as A-type motility, may be driven by the secretion and swelling of slime; however, experiments to confirm or refute this model are still lacking and the force exerted by this mechanism has not been measured. A previously published experiment found that when an M. xanthus cell became stuck at one end, the cell underwent flailing motions. Based on this experiment, I propose an elastic model that can estimate the force produced by the A-motility engine and the bending modulus of a single myxobacterial cell. The model estimates a bending modulus of 3 x 10-14 erg cm and a force between 50-150pN. This force is comparable to that predicted by slime extrusion, and the bending modulus is 30 fold smaller than that measured in Bacillus subtilis. This model suggests experiments that can further quantify this process.
Key Words:
bacteria, elasticity, gliding motility, mathematical model, myxobacteria
