Interconversion of Crystals of theEscherichia coliEF-Tu

Abstract

Crystals of the complex formed between the two bacterial polypeptide elongation factors, EF-Tu and EF-Ts, produced from solutions of PEG 6000 can be of two morphologically similar forms both of space group P2(1)2(1)2(1). One form diffracts to only about 3 A resolution, the other to better than 2.4 A resolution. These forms can be interconverted and the transformation of one into the other has been shown to be solely a result of dehydration/hydration processes. By designing a suitable soaking protocol and careful control of the experimental parameters for data collection at cryotemperatures, complete data sets for the high-resolution form could be obtained.

Crystallization and crystal manipulation of a steric chaperone in complex with its lipase substrate

“…Interestingly, the improvement of the diffraction limit appeared to be accompanied by a change in unit-cell parameters. The number of reports on crystal dehydration as a method for improving the diffraction capacity is steadily increasing (Kawashima et al, 1996;Haebel et al, 2001;Heras et al, 2003). Hence, we decided to establish a controlled dehydration protocol in order to improve the diffraction limit and collect a complete data set under cryogenic conditions.…”