Sequence of a mosquito ribonucleotide reductase cDNA and evidence for gene amplification in hydroxyurea-resistant cells

Ribonucleotide reductase is essential for production of the deoxyribonucleotide substrates required for DNA synthesis in all eukaryotic cells. The full-length cDNA encoding a mosquito ribonucleotide reductase R2 subunit was obtained from Aedes albopictus cells using a polymerase chain reaction (PCR)-based approach. The cDNA contained 1197 nucleotides, and encoded a 398 amino acid R2 protein. Overall, mosquito R2 shared approximately 70% amino acid sequence identity with R2 proteins from vertebrates, but conservation at the N-terminus of the protein was relatively low. The sequence of R2 cDNA was identical in hydroxyurea-resistant mosquito cells and in wild-type cells, while the R2 gene copy number was increased ten to twentyfold in resistant cells.