cl00257

DNA sequence specific (IHF) and non-specific (HU) domains; This family includes integration host factor (IHF) and HU, also called type II DNA-binding proteins (DNABII), which are small dimeric proteins that specifically bind the DNA minor groove, inducing large bends in the DNA and serving as architectural factors in a variety of cellular processes such as recombination, initiation of replication/transcription and gene regulation. IHF binds DNA in a sequence specific manner while HU displays little or no sequence preference. IHF homologs are usually heterodimers, while HU homologs are typically homodimers (except HU heterodimers from E. coli and other enterobacteria). HU is highly basic and contributes to chromosomal compaction and maintenance of negative supercoiling, thus often referred to as histone-like protein. IHF is an essential cofactor in phage lambda site-specific recombination, having an architectural role during assembly of specialized nucleoprotein structures (snups). Bacillus phage SPO1-encoded transcription factor 1 (TF1) is another related type II DNA-binding protein. Like IHF, TF1 binds DNA specifically and bends DNA sharply.