The cover image for the latest issue of Biophysical Journal depicts αβ-tubulin subunits near the end of a growing microtubule.   In the corresponding study, my coauthor (David J. Odde, University of Minnesota) and I utilized a Brownian dynamics approach to examine the influence of polymer end structure on the association and dissociation of individual subunits, focusing on the specific example of the microtubule.   Throughout the course of our research, we often find ourselves trying to imagine what it would be like to be a part of the system we study.  What is it like in the thermally driven chaos that is the molecular environment?  As a subunit, how would I incorporate into the polymer lattice and what would I “see” as I approach?  Besides playing to a child-like curiosity, we find these musings are indispensible in dissecting model results and predictions and often catalyze further discussion and experiments.   It was questions such as these that served as the inspiration for the cover image, capturing a microtubule from the unique perspective of a tubulin subunit.

In constructing the image, I wanted to not only create something visually engaging but also convey both the modeling approach and findings of our study.  We modeled tubulin subunits as super-ellipsoids with discretized binding zones (red, green, and blue hemispheres) forming the binding interface.  The molecular structure of ÿÿ-tubulin (PDB ID: 1TUB) shows through some subunits to indicate the coarse-grained level of our model, bridging molecular dynamics and single microtubule stochastic models.  All of the polymer end structures in question are represented in the image.  Due to competing effects, we find there is no consequence to binding sites lagging behind (lower right) longer protofilaments.  Additionally, association is attenuated at binding sites with one (left) and two (top) neighboring protofilaments of greater length compared to sites without neighboring protofilaments (lower right).   The microtubule and subunit structures shown were constructed in Grapher (Apple Inc.) using the same equations as in the model; αβ-tubulin molecular structures were rendered using Cn3D (National Center for Biotechnology Information).  The complete image was then composed in Adobe Photoshop.

I am elated to have my image selected for the cover of Biophysical Journal.  I have always had a keen interest in art and different forms of artistic media, seeing the cover art submission as a unique opportunity to explore graphic design as well as highlight my scientific research.  My coauthor and I hope that the cover image sparks interest in and encourages people to further explore our work.  The latest information on happenings in David Odde’s lab can be found at oddelab.umn.edu.

-- Brian Castle, University of Minnesota