Proteins and macromolecular structures may take on unexpected arrangements in natural fluid environments not seen in the static crystalline surroundings in which they are typically studied, according to a report in Structure.Steven Ludtke, co-director of the National Center for Macromolecular Imaging at Baylor College of Medicine and colleagues observed GroEL/GroES, a well-studied bacterial chaperonin complex that ensures proper protein folding, using cryoelectron microscopy, a technique that reconstructs three-dimensional protein structures in ultracooled samples.The researchers found two GroEL/GroES structures in solution that were not surprising based on previous X-ray crystallographic studies. However, they also found a third configuration never seen before, which Ludtke described as "a strange-looking structure blown up like a balloon."This result suggests that snapshots of macromolecular structures taken with methods such as crystallography may not be helpful in terms of understanding how dynamic protein complexes behave in their more native fluid environments."From a more global...

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