The bacterium Pseudomonas aeruginosa can thrive in environments as different as the moist, warm tissue in human lungs, and the dry, nutrient-deprived surface of an office wall. Such adaptability makes it problematic in healthcare.
According to Blanca Barquera: "These organisms are able to live everywhere, under conditions with an enormous variety of food supply, salt levels, temperature, acid/base level, and oxygen level. And we have to ask -- how can they do this?"
She adds: “In order for the organisms to survive in so many different environments, the interior of the cell must remain a hospitable place for the biochemistry of life, regardless of what happens outside. And there are proteins in the membrane that are responsible for this."
Transport proteins make up the active interface between the cell and the environment, and among the most important of these proteins are those which transport ions -- atoms or molecules with a net positive or negative electrical charge -- into and out of the cell, Barquera said. Ion transport proteins maintain favorable concentrations of ions inside the cell, and also are at the heart of energy production. Transport of positively charged hydrogen and sodium ions, called cations, create gradients that provide energy for diverse cellular processes, such as cell motility, import of nutrients, and extrusion of chemicals that are toxic to the cell.
In the current project, "Control of Na+ and H+ transport in bacterial adaptation," researchers will seek to understand how transport proteins that move hydrogen and sodium cations through the cell membrane allow Pseudomonas to adjust its metabolism to different environmental conditions.
Researchers will look at several transport proteins including NQR, which moves sodium from the interior to exterior of the cell; NUO, which moves protons from the interior to the exterior of the cell; and sodium/proton anti-porters, which exchange ions to maintain constant pH and ionic concentrations inside the cell.
Posted by Dr. Tim Sandle