Cloning, expression, purification, crystallization and preliminary X-ray diffraction analysis of intracellular growth locus E (IglE) protein from Francisella tularensis subsp. novicida

Abstract

Tularaemia is an uncommon but potentially dangerous zoonotic disease caused by the bacterium Francisella tularensis. As few as ten bacterial cells are sufficient to cause disease in a healthy human, making this one of the most infectious disease agents known. The virulence of this organism is dependent upon a genetic locus known as the Francisella pathogenicity island (FPI), which encodes components of a secretion system that is related to the type VI secretion system. Here, the cloning, expression, purification and preliminary X-ray diffraction statistics of the FPI-encoded protein IglE are presented. This putative lipoprotein is required for intra-macrophage growth and is thought to be a constituent of the periplasmic portion of the type VI-like protein complex that is responsible for the secretion of critical virulence factors in Francisella.

Figure 1

Crystal of IglE grown in 30%(v/v) PEG 400, 70 mM CdCl₂, 100 mM sodium acetate pH 4.4. Crystal dimensions are 0.3 × 0.1 × 0.1 mm.

Figure 2

X-ray diffraction image of IglE crystals, showing diffraction to 1.90 Å resolution.