A NOVEL DROSOPHILA-MINUTE LOCUS ENCODES RIBOSOMAL-PROTEIN-S13

Minutes comprise >50 phenotypically similar Drosophila mutations belie ved to affect ribosomal protein genes. Common traits of the Minute phe notype are short and thin bristles, slow development, and recessive le thality. To further investigate the proposed Minute to ribosomal prote in correspondence, loss-of-function Minute mutations were induced by P -element mutagenesis. Here, we report a previously undescribed Minute locus that maps to 32A on chromosome 2L; this Minute allele is named P {lacW}M(2)32A' and the gene M(2)32A. Flies heterozygous for P{lacW}M(2 )32A' have a medium Minute phenotype. The gene interrupted by the P-el ement insertion was cloned. Sequence analyses revealed that it encodes the Drosophila homologue of eukaryotic ribosomal protein S13. It is a single-copy gene and the level of RPS13 transcript is reduced to simi lar to 50% in P{lacW}M(2)32A' heterozygotes. Both transcript level and phenotype are restored to wild type by remobilizing the P element, de monstrating that the mutation is caused by insertion of the P-element construct. These results further strengthen the notion that Minutes en code ribosomal proteins and demonstrate that P-element mutagenesis is a fruitful approach to use in these studies.