On the quaternary structure of a C-type lectin from Bothrops jararacussu venom – BJ-32 (BjcuL)

BJ-32 (also known as BjcuL) is a C-type lectin from the venom of Bothrops jararacussu with specificity for β-galactosides and a remarkable ability to agglutinate several species of trypanosomatids. Our objective was to study the oligomerization state of native BJ-32 by using different biophysical and computational methods. Small-angle X-ray light scattering (SAXS) experiments disclosed a compact, globular protein with a radius of gyration of 36.72 ± 0.04 Å and molecular weight calculated as 147.5 ± 2.0 kDa. From analytical ultracentrifugation analysis, it was determined that the BJ-32 sedimentation profile fits nicely to a decamer model. The analysis of the intrinsic emitted fluorescence spectra for BJ-32 solutions indicated that association of subunits in the decamer is accompanied by changes in the environment of Tryptophan residues. Both ab initio and comparative models of BJ-32 supported the resemblance of the decamer in the crystallographic structure from a close homologue, the rattlesnake venom lectin (RSL) from Crotalus atrox.