Practice question

Lambda Int alone binds weakly and cannot efficiently synapse attP and attB due to distance between core and arm sites exceeding 150 base pairs. Integration Host Factor, a heterodimeric histone-like protein, binds H' sequences in attP introducing sharp >160 degree bend. This bending juxtaposes distant Int arm-binding sites near core, allowing cooperative binding of Int oligomers and formation of intasome nucleoprotein architecture. IHF also modulates local supercoiling and facilitates site juxtaposition through DNA deformability, greatly enhancing recombination efficiency, while excision requires additional Xis and Fis proteins remodeling intasome differently.