Mutations in HU and IHF affect bacteriophage T4 growth: HimD subunits of IHF appear to function as homodimers

The Escherichia coli nucleoid-associated DNA-binding proteins HU and IHF are required for numerous biological processes, including phage growth (e.g., lambda, phi 80, Mu and f1) and DNA replication. Here, we show that growth of T4 phage is inhibited both in hupA hupB and himA himD double mutants. The growth profile of triple mutants (hupA hupB himA and hupA hupB himD) suggests that HimD subunits can form homodimers, which are functionally competent for supporting in vivo growth of phage T4.