Purification, crystallization, and preliminary X-ray crystallographic data analysis of small heat shock protein homolog from Methanococcus jannaschii, a hyperthermophile

A gene coding for a small heat shock protein homolog from the hyperthermophilic methanogenic Archaeon Methanococcus jannaschii was cloned. This gene was overexpressed in Escherichia coli harboring rare codon tRNAs and its protein purified and crystallized. Crystals displayed the space group R3 with unit cell dimensions a = b = 171.46 A and c = 102.13 Šin a hexagonal axis setting. These crystals grew in one week and diffracted to 3.2 Šresolution. The presence of eight molecules in the asymmetric unit gives a V(m) value of 2.2 ų/Da and a solvent content of 44% by volume. The 24- molecule complex is generated from a subunit by a combination of crystallographic threefold symmetry and three types of noncrystallographic symmetries (a two-, a three-, and a fourfold).