THE DROSOPHILA-MELANOGASTER GENOME CONTAINS A MEMBER OF THE RH/T-2/S-GLYCOPROTEIN FAMILY OF RIBONUCLEASE-ENCODING GENES

Members of the Rh/T-2/S-glycoprotein family of ribonuclease(RNase)-encoding genes have been found predominantly in fungi, plants and bacteria, where they have been implicated in functions as diverse as the phosphate-starvation response and self-incompatibility. We report the isolation and sequence of DmRNase-66B, the first member of this family to be found in an insect genome. This gene was identified by the analysis of a cDNA clone derived from cytological region 66B1-2 of the genome of Drosophila melanogaster. In a search of sequence databases for homologs of this gene, two animal viral proteins, gp53 of the bovine viral diarrhea virus (BVDV) and gp44/48 of the hog cholera virus (HCV), were also found to exhibit the characteristic features of this class of RNases. In all cases, the proteins contain two conserved pentameric amino-acid regions that have been shown to lie in the active site of these RNases. A series of Cys residues are also conserved in all members of this gene family. The discovery of members of this family of genes in an insect genome indicates that these RNases are widely conserved and play important roles in the animal, as well as the plant and prokaryotic kingdoms.