Crystallization and preliminary crystallographic analysis of a novel haemolytic lectin from the mushroom Laetiporus sulphureus

The novel haemolytic lectin from the parasitic mushroom Laetiporus sulphureus (LSL) is a homotetramer (∼140 kDa) composed of subunits associated by non-covalent bonds. It exhibits haemagglutin­ation and haemolytic activities, both of which are inhibited by N-­acetyllactosamine. The structural similarity found between LSL and the bacterial pore-forming toxins mosquitocidal toxin (MTX2) from Bacillus sphaericus and α-toxin from Clostridium septicum points to a mechanism of biological action involving the formation of pores in the target membranes. LSL has been crystallized using the hanging-drop vapour-diffusion method at 291 K. Diffraction-quality hexagonal crystals have unit-cell parameters a = b = 101.8, c = 193.9 Å and belong to space group P6₃22. A 2.7 Å native data set was collected with an R_merge of 9.2%.