Expression, crystallization, and preliminary X-ray crystallographic analysis of putative SpoVG from Staphylococcus aureus

Abstract

SpoVG, originally identified in spore-forming Bacillus subtilis was known to be involved in spore formation of B. subtilis stationary phase cells at stage V. Later, close homologues of SpoVG of B. subtilis are shown to be present in the genomes of several nonsporulating bacteria as well. Especially in Staphylococcus aureus, SpoVG is speculated to be the major factor of the yabJ-spoVG operon required for capsule formation and methicillin and glycopeptides resistance. The putative SpoVG from S. aureus, a homodimeric protein consisting of two identical 100-residue subunits, has been overexpressed in Escherichia coli with a C-terminal purification tag and crystallized at 293 K using a precipitant solution consisting of 1.9 M (NH₄)₂SO₄, 100 mM Tris-HCl, pH 7.5. X-ray diffraction data were collected to 3.10 Å at 100 K. The crystals belong to the primitive tetragonal space group P41 (or P4₃), with unit cell parameters of a = b = 92.239, c = 98.588 Å, α = β = γ = 90°. Two dimers are present in the crystallographic asymmetric unit, with a calculated crystal volume per protein weight (V_M) of 4.37 ųDa⁻¹ and a solvent content of 71.9%.