PSEUDOMONAS-AERUGINOSA CONTAINS AN IHF-LIKE PROTEIN THAT BINDS TO THE ALGD PROMOTER

An IHF-like protein has been purified from a Pseudomonas aeruginosa strain isolated from a cystic fibrosis patient, by the rapid purification method described for the isolation of IHF from Rhodobacter capsulatus. This IHF of P. aeruginosa is an αβ heterodimer (subunits of 10 and 11 kDa) similar to IHF from Escherichia coli and from R. capsulatus; the N-terminal amino acid sequences of the isolated subunits share a high degree of identity with their homologs from E. coli. P. aeruginosa IHF is able to bind to the promoter of the hydrogenase structural genes (hupSL) of R. capsulatus as do the other two IHF proteins. It is also demonstrated by gel retardation assays that P. aeruginosa IHF forms a stable complex with the algD promoter in vitro, an indication that the protein is involved in the regulation of algD gene expression in P. aeruginosa. © 1993 Academic Press, Inc.