Purification, crystallization and preliminary crystallographic analysis of avian infectious bronchitis virus nsp3 ADRP domain.

Avian infectious bronchitis virus (IBV) encodes 15 nonstructural proteins (nsps) which play crucial roles in RNA transcription and genome replication. One of them, nsp3, contains an ADRP (adenosine diphosphate-ribose-1'-phosphatase) domain which was revealed in recent studies to have ADP-ribose-1'-monophosphatase (Appr-1'-pase) activity. Appr-1'-pase catalyzes the conversion of ADP-ribose-1'-monophosphate (Appr-1'-p) to ADP-ribose in the tRNA-splicing pathway. The gene segment encoding the IBV nsp3 ADRP domain has been cloned and expressed in Escherichia coli. The protein has been crystallized and the crystals diffracted to 1.8 A resolution. They belonged to space group P1, with unit-cell parameters a = 41.1, b = 43.2, c = 48.9 A, alpha = 78.0, beta = 80.0, gamma = 73.6 degrees . Each asymmetric unit contains two molecules.