Expression, purification and crystallization of the C-terminal LRR domain of Streptococcus pyogenes protein 0843.

Streptococcus pyogenes protein 0843 (Spy0843) is a recently identified protein with a potential adhesin function. Sequence analysis has shown that Spy0843 contains two leucine-rich repeat (LRR) domains that mediate interactions with the gp340 receptor. Here, the C-terminal LRR domain was overexpressed in Escherichia coli, purified and crystallized in the presence of 1.7–1.8 M ammonium sulfate pH 7.4 as precipitant. Data were collected from a single crystal to 1.59 A resolution at 100 K at a synchrotron-radiation source. The crystal was found to belong to space group I41, with unit-cell parameters a = b = 121.4, c = 51.5 A and one molecule in the asymmetric unit. Elucidation of the crystal structure will provide insights into the interactions of Spy0843 with the gp340 receptor and a better understanding of the role of Spy0843 in streptococcal infections.