Unless a helical polymer has exactly 2, 3, 4 or 6 subunits per turn, it cannot be crystallized so that every subunit is in an equivalent environment. That is why so few crystal structures exist for protein polymers, which are highly abundant in biology, and why electron cryo-microscopy has emerged as one of the most useful tools for studying these filaments. However, cryo-EM studies of most protein polymers do not directly lead to high resolution structures due to the substantial degree of disorder and variability that is present. We have developed a number of methods for surmounting these problems, and the applications of these methods to a range of polymers, from bacterial pili to recombination filaments, have suggested some general principles, such as the lability of quaternary structure. Many of these insights are only possible due to the complementarity between x-ray crystallography and cryo-EM.

Cryo-EM of helical polymers: New insights into evolutionary divergence

245th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.