Crystallization of truncated hemolysin A from Proteus mirabilis

Abstract

Proteus species are second only to Escherichia coli as the most common causative agent of Gram-negative bacteria-based urinary-tract infections and many harbor several virulence factors that provide inherent uropathogenicity. One virulence factor stems from a two-partner secretion pathway comprised of hemolysin A and hemolysin B; upon hemolysin B-dependent secretion, hemolysin A becomes activated. This system is distinct from the classic type I secretion pathway exemplified by the hemolysin system within Escherichia coli. In order to describe the mechanism by which hemolysin A is activated for pore formation, an amino-terminal truncated form capable of complementing the non-secreted full-length hemolysin A and thereby restoring hemolytic activity has been constructed, expressed and purified. A room-temperature data set has been collected to 2.5 A resolution. The crystal belongs to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 34.47, b = 58.40, c = 119.74 A. The asymmetric unit is expected to contain a single monomer, which equates to a Matthews coefficient of 1.72 A3 Da(-1) and a solvent content of 28.3%.

Figure 1

Native crystal of truncated hemolysin A from P. mirabilis.

Figure 2

X-ray diffraction image from a truncated hemolysin A crystal. The edge of the detector corresponds to 1.6 Å resolution.