These pathogens gain entry the same way millions of receptors on the cell's surface routinely do after they get activated, says Dr. Yehia Daaka, professor and Distinguished Chair in Oncologic Pathology at the Medical College of Georgia. Dr. Daaka is corresponding author on an article published Jan. 23 by Proceedings of the National Academy of Sciences.
By moving off the cell surface, receptors gain some respite from their activating signals, Dr. Daaka says. Receptors can either stay inside the newly created vesicle and be degraded or resurface to be activated once again.
Bacteria and viruses also want inside cells and out of the direct line of fire of the immune system or treatments such as antibiotics for bacterial infections, Dr. Daaka says. "Some bacteria and viruses bind to receptors on the plasma membrane and use them to go inside, and that is how they start replicating inside the cell," he says.
He and colleagues at Howard Hughes Medical Institute and Duke University Medical Center also have found that the short-lived, ubiquitous gas, nitric oxide, is a primary enabler for receptors and pathogens to make this move.
"When there is a signal, the plasma membrane on the cell surface invaginates ?think of a plasma membrane as a balloon and you poke your finger in it," he says. "The protein, dynamin, comes along and forms a necklace around the neck of that balloon, then chops it off," he says of the process that is ongoing with millions of receptors on the cell surface. "Adding nitric oxide to dynamin changes it from an inactive protein inside the cell to the active protein that mediates the fission of the vesicle inside the cell."
Apparently, bacteria and viruses can increase nitric oxide levels to make this normally protective system work for them as well.
Identifying this role of nitric oxide provides a new targ
Source:Medical College of Georgia