Identification and characterization of the RAD51 gene from the ciliate Tetrahymena thermophila

The RAD51 gene is a eukaryotic homolog of recA, a critical component in homologous recombination and DNA repair pathways in Escherichia coli. We have cloned the RAD51 homolog from Tetrahymena thermophila, a ciliated protozoan. Tetrahymena thermophila RAD51 encodes a 36.3 kDa protein whose amino acid sequence is highly similar to representative Rad51 homologs from other eukaryotic taxa. Recombinant Rad51 protein was purified to near homogeneity following overproduction in a bacterial expression system. The purified protein binds to both single- and double-stranded DNA, possesses a DNA-dependent ATPase activity and promotes intermolecular ligation of linearized plasmid DNA. While steady-state levels of Rad51 mRNA are low in normally growing cells, treatment with UV light resulted in a >100-fold increase in mRNA levels. This increase in mRNA was time dependent, but relatively independent of UV dose over a range of 1400–5200 J/m2. Western blot analysis confirmed that Rad51 protein le...

• Type: Journal
• Year: 1998
• Where: NAR
• Authors: Colin Campbell, Daniel P. Romero
• Keywords: NAR 1998, Protein, Rad51, Tetrahymena Thermophila