RNA-protein interactions of the bacteriophage RB69 RegA translational repressor protein

We report the RNA-protein interactions of phage RB69 RegA and RegA691 proteins. In RNase protection assays, RB69 RegA protects from 10 (44 mRNA) to >70 (rpbA) nucleotides; for rpbA in particular, the length of the protected region is RegA-concentration dependent. Quantitative fluorescence quenching measurements with RB69 wildtype RegA and RegA691 show that both proteins bind poly(U) similarly, but RegA691 binds with lower affinity to both 44 and rpbA RNA. The results indicate that both RB69 RegA RNA-protein and protein-protein interactions contribute to a translational repression hierarchy.