Crystal cryocooling distorts conformational heterogeneity in a model Michaelis complex of DHFR.

ABSTRACT: Most macromolecular X-ray structures are determined from cryocooled crystals, but it is unclear whether cryocooling distorts functionally relevant flexibility. Here we compare independently acquired pairs of high-resolution data sets of a model Michaelis complex of dihydrofolate reductase (DHFR), collected by separate groups at both room and cryogenic temperatures. These data sets allow us to isolate the differences between experimental procedures and between temperatures. Our analyses of multiconformer models and time-averaged ensembles suggest that cryocooling suppresses and otherwise modifies side-chain and main-chain conformational heterogeneity, quenching dynamic contact networks. Despite some idiosyncratic differences, most changes from room temperature to cryogenic temperature are c

SUBMITTER: Keedy DA 

PROVIDER: S-EPMC4082491 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature