Particle picking

Computer scientists and biologists at the US Department of Energy’s Lawrence Berkeley National Laboratory have developed software that can select tens of thousands of high-quality images of biological molecules from electron microgaphs, rapidly and automatically, with accuracy approaching that of experienced human analysts.

The new algorithm, described as “particle picking by segmentation,” promises to greatly increase the speed and power of methods for determining biological structures at high resolution, based on data from electron microscopy. The researchers report their results in the forthcoming issue of the Journal of Structural Biology.

When what’s needed is a high-resolution structure of a large and complicated biological molecule - such as a ribosome, which combines protein and RNA, or a membrane protein that readily falls apart in water and is hard to crystallise - biologists often turn to cryo-electron microscopy (cryo-EM) to perform single-particle reconstruction.

Understanding structure is often the key to devising antibiotics and other therapies that can interfere with unwanted biological activity. Single-particle reconstruction with cryo-EM holds the promise of providing many high-resolution structures which may be difficult or impossible to obtain otherwise.