Molecular characterisation of the deep orange (dor ) gene of Drosophila melanogaster

Abstract

Mutations of the dor gene of Drosophila melanogaster cause defects in different stages of development. Heterozygotes for lethal or viable dor alleles and the rearrangement T(1;2)dor ^var7, which causes position effect variegation of dor, exhibit traits such as rough eyes, reduction of bristles on the thorax and scutellum and wavy wings. The dor gene was mapped to the proximal part of the 2B3-5 band or in the interband between 2B3-5 and 2B6 and localised within an interval of 5 kb on the physical map of the cloned 2B region. The 3.0–3.1 kb dor transcript was detected by Northern hybridization at all stages of development and is expressed in salivary glands of third instar larve. This RNA was not expressed in the dor mutants with insertions in the 5′ part of the gene. The sequence of the 3180 bp dor cDNA predicts a 115.3 kDa protein that contains a cysteine- and histidine-rich zinc finger-like motif CX₂CX₁₃CXHX₂HX₂CX₂H at the C-terminus. The protein sequence reveals 23% identity to the Saccharomyces cerevisiae PEP3 protein. The most significant homology (57% similarity and 32% identity) between the DOR and PEP3 proteins is observed at the C-termini of the proteins.