Abstract
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.