Danko Georgiev earned his M.D. from Medical University of Varna, Bulgaria, graduating summa cum laude in 2004. He obtained a Ph.D. from Kanazawa University, Japan, in 2008 following his research in the area of neuronal differentiation. From 2009 to 2011 he was awarded JSPS Post Doctoral Fellowship by the Japan Society for the Promotion of Science. Currently he is a Post Doctoral Researcher at the Department of Psychiatry and Neurobiology, Kanazawa University. He is a member of the Japanese Society of Neuropsychopharmacology since 2007, member of the Japan Neuroscience Society since 2010, and a member of the Society for Neuroscience since 2010.
Conformational Dynamics and Thermal Cones of C Terminal Tubulin Tails in Neuronal Microtubules
Danko Georgiev, James F. Glazebrook
In this paper we present a model for estimation of the C-terminal tubulin tail (CTT) dynamics in cytoskeletal microtubules of nerve cells. We show that the screened Coulomb interaction between a target CTT and the negatively charged microtubule surface as well as its immediate CTT neighbours results in confinement of the CTT motion within a restricted volume referred to as a thermal cone. Within the thermal cone the CTT motion is driven by the thermal fluctuations, while outside the thermal cone the CTT interaction energy with its environment is above the thermal energy solely due to repulsion from the negatively charged microtubule surface. Computations were performed for different CTT geometries and we have found that the CTT conformation with lowest energy is perpendicular to the microtubule surface. Since the coupling between a target CTT with its neighbour CTTs is 8 orders of magnitude below the thermal energy and considering the extremely short cytosolic Debye length of 0.79 nm, our results rule out generation and propagation of CTT conformational waves along the protofilament as a result of local CTT perturbations. The results as presented support a model in which the cytosolic electric fields and ionic currents generated by the neuronal excitations are “projected” onto the CTTs of underlying microtubules thus affecting their regulatory function of kinesin motion and MAP attachment/detachment.