Gene, 158 (1995) 203-207 ©1995 Elsevier Science B.V. All rights reserved. 0378-1119/95/$09.50 203 GENE 08685 The Drosophilamelanogaster genome contains a member of the Rh/Tz/S-glycoprotein family of ribonuclease-encoding genes (Viral protein; self-incompatibility; insect; sequence homology; viral RNase) Gary Hime*, Leanne Prior* and Robert Saint Department of Biochemistry, University of Adelaide, Adelaide, SA 5005, Australia Received by P.A. Manning: 28 February 1994; Revise&Accepted: 11 October/13 October 1994; Received at publishers: 8 December 1994 SUMMARY Members of the Rh/T2/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-incomp~.tibility. 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. INTRODUCTION The number of proteins shown to exhibit RNase activ- ity has been greatly exp~Lnded in recent years with the discovery of new classes of RNases involved in cell metab- olism and gene regulation. Many of these proteins were Correspondence to: Dr. R. Saint at his present address: Department of Genetics, University of Adelaide, Adelaide, SA 5005, Australia. Tel. (61-8) 303-4043; Fax (61-8) 303.-4399; e-mail: RSaint@gina.science ade.laide.edu.au *Present addresses: (L.P.) Department of Genetics, University of Adelaide, Adelaide, SA 5005, Australia. Tel. (61-8) 303-4043; (G.H.) Department of Developmental ]3iology, Stanford University School of Medicine, Stanford, CA 94305-_';427, USA. Tel. (1-415) 723-9703. Abbreviations: aa, amino acid(s); AED, after egg deposition; bp, base pair(s); BVDV, bovine viral diarrhea virus; cDNA, DNA complemen- tary to RNA; D., Drosophila; Din., D. melanogaster; gp, glycoprotein; HCV, hog cholera virus; kb, kilobase(s) or 1000 bp; nt, nucleotide(s); ORF, open reading frame; S-glycoprotein, stylar glycoprotein; UTR, untranslated region(s). first identified as effectors of biological processes before their ribonuclease activity became apparent. One of the most interesting examples is self-incompatibility in game- tophytic plants which is controlled by a single multi- allelic locus (Anderson et al., 1986; 1989; McClure et al., 1989; Ioerger et al., 1990). In Nicotiana alata, this locus encodes proteins termed the stylar glycoproteins (S-glycoproteins; Anderson et al., 1986) which exhibit homology with the fungal RNases T 2 and Rh, from Aspergillus oryzae and Rhizopus niveus (McClure et al., 1989). Elucidation of the crystal structure of RNase Rh has shown these two conserved regions to be part of the active site of the enzyme (Kurihara et al., 1992). Subsequently, RNases of this family have been isolated from styles of Petunia sp. (Ai et al., 1990; Clark et al., 1990) and Solarium ehaeoense (Xu et al., 1990), developing fruit of Lycopersicon esculentum (Nurnberger et al., 1990; Jost et al., 1991; Loftier et al., 1992; 1993), seeds of Momordica charantia (Ide et al., 1991) and tubers of SSDI 0378-1119(94)00896-5