Our lab solved the structure of the intrinsically flexible addiction antidote MazE (blue), using a nM affinity Xaperone (red) as a crystallization chaperon. The Xaperone generates a crystal lattice with a cavity that accomodates the intrinsically unfolded part of MazE. Remarkably, more than half of MazE is disordered in the crystal, shedding light on the difficulty of crystallizing MazE in isolation. In complex with the antibody fragment, the total amount of structured polypeptide (126 amino acids of Xaperone and 44 amino acids of MazE) rises to 73% compared with 45% of free MazE, thus providing a much better starting point for crystallization.

Loris R, Marianovsky I, Lah J, Laeremans T, Engelberg-Kulka H, Glaser G, Muyldermans S & Wyns L (2003) Crystal structure of the intrinsically flexible addiction antidote MazE. J Biol Chem 278, 28252-28257.