Rules of Expansion: an Updated Consensus Operator Site for the CopR-CopY Family of Bacterial Copper Exporter System Repressors
Henrik O’Brien, Joseph W. Alvin, Sanjay V. Menghani, Yamil Sanchez-Rosario, Koenraad Van Doorslaer, Michael D. L. Johnson
Abstract
Many Gram-positive bacteria respond to copper stress by upregulating a copper export system controlled by a copper-sensitive repressor, CopR-CopY. The previous operator sequence for this family of proteins had been identified as TACANNTGTA. Here, using several recombinant proteins and mutations in various DNA fragments, we define those 10 bases as necessary but not sufficient for binding and in doing so, refine the cop operon operator to the 16-base sequence RNYKACANNTGTMRNY. Due to the sheer number of repressors that have been said to bind to the original 10 bases, including many antibiotic resistance repressors such as BlaI and MecI, we feel that this study highlights the need to reexamine many of these sites of the past and use added stringency for verifying operators in the future.