The ihf mRNA levels decline as Neisseria gonorrhoeae enters the stationary growth phase.

Integration host factor (IHF) is a small heterodimeric DNA binding protein found in all Gram-negative bacteria and is implicated as a transcription cofactor of pilE in Neisseria gonorrhoeae (Hill, S.A., Samuels, D.S., Carlson, J.H., Wilson, J., Hogan, D., Lubke, L., Belland, R.J., 1997. Integration host factor is a transcriptional cofactor of pilE in Neisseria gonorrhoeae. Mol. Microbiol. 23, 649-656). The ihf genes (ihfA and ihfB) were cloned from N. gonorrhoeae through functional complementation of defined Escherichia coli ihf mutants for plating of phage lambda. The predicted aa sequences of each gonococcal IHF polypeptide showed extensive homology to other reported IHF polypeptide sequences. Northern blotting and primer extension analysis defined the tsp for each gene and indicated a disparity in ihfA and ihfB message levels over time, with ihfB mRNA being more abundant throughout the entire growth cycle. Furthermore, both the ihfA and ihfB message levels declined as cells entered the stationary growth phase. Overall, this study reveals several unique features of ihf transcription in the gonococcus which questions whether certain aspects if ihf transcriptional regulation are universally shared by all Gram-negative bacteria.