Disease relevance of oprH

• Two overlapping open reading frames that encoded proteins with high similarities to the PhoP-PhoQ two-component regulatory system of Salmonella typhimurium were identified downstream of the oprH gene [1].
• The cloned oprH gene of Pseudomonas aeruginosa was mutated by inserting a 1.4-kbp fragment that encodes tetracycline resistance [2].
• A 2.8-kb EcoRI fragment containing the oprH gene was subcloned into several different expression plasmids in Escherichia coli [3].

High impact information on oprH

• Growth of the resultant oprH::tet mutant in Mg(2+)-deficient medium had little effect on susceptibility to polymyxin B, gentamicin, or EDTA unless the mutant was complemented by the cloned oprH gene in plasmid pGB25 [2].
• The genes for this system form an operon with oprH, oprH-phoP-phoQ, that responds to Mg(2+) starvation and PhoP levels [4].

Biological context of oprH

• This was true regardless of whether OprH overexpression was induced by growth of strain H103 on Mg(2+)-deficient medium, the addition of 5 mM m-toluate to cells containing the cloned oprH gene behind the inducible tol promoter in plasmid pGB25, or mutation in the polymyxin-resistant derivative strain H181 [5].
• In this study, the Mg(2+)-regulated promoter for this operon was mapped upstream of oprH by primer-extension experiments [4].

References