The Pseudomonas aeruginosa heme utilization (Phu) system encodes quite a few proteins involved thorough from the acquisition of heme as an iron supply. The moment internalized, heme is degraded by the iron-regulated heme oxygenase, Hem() to biliverdin (By) IX delta and beta. In vitro studies have shown holo-PhuS transfers heme towards the iron-regulated HemO. This protein-protein interaction is precise for HemO as PhuS won't interact together with the alpha-regioselective heme oxygenase, BphO. Bacterial genetics and isotopic labeling (C-13-heme) research confirmed extracellular heme is converted to C-13-BVIX delta and beta via the catalytic action of HemO. In an effort to even more comprehend the function of PhuS, equivalent scientific studies were performed on the P. aeruginosa PAO1 Delta phuS and Delta phuS/Delta hemO Selinexor (KPT-330) strains.
In contrast to wild-type strain, the absence of PhuS success in extracellular heme uptake and degradation by way of the catalytic action of Hem and BphO. At very low heme concentrations, reduction of PhuS results in inefficient extracellular heme uptake supported through the fact the mRNA levels of PhuR, HemO, and BphO remain elevated when in contrast to the wild-type PAO1. On escalating extracellular heme concentrations, the elevated levels of PhuR, HemO, and BphO enable "leaky uptake" and degradation of heme through Hem() and BphO. Similarly, during the Delta phuS/Delta hemO strain, the greater heme concentrations mixed with elevated amounts of PhuR and BphO results in nonspecific heme uptake and degradation by BphO. So we propose heme flux into the cell is driven from the catalytic actionABT-737 of HemO with PhuS acting being a "control valve" to manage extracellular heme flux.