Mosquito ribosomal protein S3 lacks a critical glutamine residue associated with DNA repair activity in homologous Drosophila proteins.

In Drosophila melanogaster, ribosomal protein RpS3 has extra-ribosomal activities including apurinic/apyrimidinic lyase activity and N-glycosylase activity that participate in DNA repair. It has been suggested that these activities couple DNA repair to the translational machinery. To establish a basis for participation of RpS3 in DNA repair in mosquitoes, we cloned RpS3 cDNAs from Aedes aegypti and Aedes albopictus mosquito cell lines. The sequence data were used to reconstruct the homologous gene from the Anopheles gambiae database. Mosquito RpS3 is a single copy gene, which in Aedes albopictus, lacks introns in the amino acid coding region. Although RpS3 proteins are well-conserved among eukaryotes, a critical glutamine residue, Q59, essential to robust DNA repair activity in the Drosophila protein, is replaced by an asparagine (N) in all three mosquito RpS3 proteins. In this respect, the mosquito protein resembles human RpS3, which has relatively modest DNA repair activity. None of the insect RpS3 proteins available in the database, other than those from Drosophila, contain glutamine at position 59. However, in the Lepidoptera, N59 is consistently replaced by serine (S), and the putative interactive site at position 134 is replaced by arginine (R). These data suggest that in the case of RpS3, the Drosophila protein may be uniquely unusual in having robust DNA repair activities that are unlikely to be common to RpS3 from other insects.