Engineering Approaches to Biomolecular Motors

Engineering Approaches to Biomolecular Motors: From in vitro to in vivo Poster Abstracts

32-POS Board 32 Understanding the Role of ATP in Active Self-organization of Microtubule Spools Amanda J. Tan 1 , Dail E. Chapman 2 , Linda S. Hirst 1 , Jing Xu 1 . 1 University of California, Merced, CA, USA, 2 University of California, Irvine, CA, USA. Self-organization of microtubules into ring-shaped structures (“spools”) constitutes a model system for studying active material. To form microtubule spools, biotinylated microtubules are shuttled atop a motor-coated surface as in standard gliding assays; binding between microtubules is mediated by streptavidin. While the mechanisms underlying microtubule spool formation remain unclear, it is known that considerable energy (10 5 k B T) is required to deform microtubules to form spools. Here, we investigated the role of kinetic energy input (ATP) in microtubule spool formation. We systematically varied the ATP concentration in our experiments and examined the steady state size and number density of microtubule spools formed under otherwise identical conditions. Surprisingly, we found that although ATP is necessary to initiate spool formation and to sustain spool rotation, the steady state of microtubule self-organization is not sensitive to ATP concentration. We detected no significant changes in the morphology (spool circumference) or the probability of microtubule spools formed (number density) over a 20-fold range in ATP concentration (0.05 – 1 mM). Our study indicates that microtubule spool formation is not directly coupled to any particular level of kinetic energy input. Lowering the ATP concentration, which slows the kinetic rate of microtubule self- organization, may therefore be a useful experimental approach for understanding the mechanisms underlying microtubule spool formation.

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