Preliminary crystallographic analysis of avian infectious bronchitis virus main protease

Infectious bronchitis virus (IBV) is the prototype of the genus Coronavirus. It causes a highly contagious disease which affects the respiratory, reproductive, neurological and renal systems of chickens, resulting great economic losses in the poultry industry worldwide. The coronavirus (CoV) main protease ( M pro), which plays a pivotal role in viral gene expression and replication through a highly complex cascade involving the proteolytic processing of replicase polyproteins, is an attractive target for antiviral drug design. In this study, IBV M pro was overexpressed in Escherichia coli. Crystals suitable for X-ray crystallography have been obtained using microseeding techniques and belong to space group P6(1)22. X-ray diffraction data were collected in-house to 2.7 angstrom resolution from a single crystal. The unit-cell parameters were a = b = 119.1, c = 270.7 angstrom, alpha = beta = 90, gamma = 120 degrees. Three molecules were predicted to be present in the asymmetric unit from a calculated self-rotation function.