Enhancer function requires the bacterial Fis protein (named because it was discovered as afactor for inversion stimulation).Like IHF, Fis is a site-specific DNA-bending protein.In addition, it makes protein–protein contacts with Hin that are important for recombination.The Fis–enhancer complex activates the catalyticsteps of recombination.Hin can actually assemble and pair the hix recombination sites to form a synaptic complex in the absence of the Fis–enhancer complex (Fig. 12-14).This contrasts with the role of IHF in λ integration, where the accessory protein is essential for assembly of the recombinase–DNA complex.