Bacteriophage lambda repressor mediates the formation of a complex enhancer-like structure.

The authors discuss aspects of the bacteriophage lambda which mediates complex enhancer-like structure formation. They described the work by J. W. Little and C. B. Michalowski which shows that mutation of the integration host factor (IHF) site at OL decreased UP element-mediated PRM lysogenic promoter stimulation. It mentions that the distal OL operator of lambha has the determining properties of a complex enhancer.