Purification, Crystallization, and Preliminary X-Ray Crystallographic Data Analysis of Small Heat Shock Protein Homolog fromMethanococcus jannaschii,a Hyperthermophile

Abstract

A gene coding for a small heat shock protein homolog from the hyperthermophilic methanogenic ArchaeonMethanococcus jannaschiiwas cloned. This gene was overexpressed inEscherichia coliharboring rare codon tRNAs and its protein purified and crystallized. Crystals displayed the space group R3 with unit cell dimensionsa=b= 171.46 Å andc= 102.13 Å in a hexagonal axis setting. These crystals grew in one week and diffracted to 3.2 Å resolution. The presence of eight molecules in the asymmetric unit gives aVmvalue of 2.2 Å3/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).