GT1b (OO16323) is a branched oligosaccharide and one of the receptors found on BK polyomavirus (BKV). BKV is responsible for polyomavirus-associated nephropathy and hemorrhagic cystitis in immunocompromised individuals. With the limited options of treatments available, determining the structure of the infectious BKV virion, in complex with its receptors, will aid in the development of new therapies.
Crystallographic soaking could not be employed for studying the structure of BKV in complex with GT1b, due to steric restrictions. Therefore, cryoelectron microscopy (cryo-EM) was alternatively used, whereby carbon-immobilized virions were treated with the oligosaccharide component of GT1b at 20 mM solution. This was followed by blotting and plunge freezing. This method resolved the structure of BKV alone (at 3.8 Å resolution) as well as in complex with GT1b (at 3.4Å resolution). Furthermore, no changes in conformation have been detected upon binding of GT1b to BKV. This suggests that these receptors function as facilitators of BKV entry into cells. The structure of BVK-GT1b complex will provide a tool for future in silico studies of new molecular targets against BKV.
For further information, please refer to the original paper: Hurdiss et al, (2018).