Researchers recently discovered bacteria that fed on the element manganese. Scientists also know that some bacterial pathogens obtain manganese from their human hosts, and now a gateway behind this manganese-scavenging has been revealed for Streptococcus pneumoniae (pneumococcus) bacteria. This work, which has been reported in Science Advances, could help researchers develop new drugs to target antibiotic resistant pathogens.
Pneumococcus is the primary cause of bacterial pneumonia, which is estimated to cause one million deaths or more every year, and is the leading cause of death in young children. The bacteria can also cause ear infections, meningitis, and sepsis.
Cells, including single-celled bacteria, are enclosed by a membrane, which keep out unwanted material and are critical to survival. But those cell membranes have to allow some things in, like nutrients. For pneumococcus, manganese is an essential nutrient, and the microbe has a channel that the manganese passes through. In this study, the researchers have deciphered the structure of that channel.
When the researchers were studying the pneumococcus bacteria, they observed that the nutrients seemed to be drawn into the cell in a controlled way, said University of Melbourne Associate Professor Megan Maher. "Eventually we discovered that this was due to a unique gateway that sits in the bacterium's membrane that opens and closes to specifically allow manganese in," said Maher.
"This is a completely new structure that has never been seen in a pathogen like this," said University of Melbourne Professor Christopher McDevitt, who added that this work has changed our assumptions about the survival of this pathogen.
"Previously, it was thought that these gateways acted like Teflon coated channels in the sense that everything just flowed through." McDevitt explained. "Now we understand that it is selectively drawing the manganese in. Any disturbance of this gateway starves the pathogen of manganese, which prevents it from being able to cause disease."
Antibiotic resistance is a growing problem that's already thought to cause over 700,000 deaths every year around the world. This finding may help pave the way to new therapeutics that fight pneumococcus. The current pneumococcal vaccine only protects people from a few circulating strains.
"It's a really attractive therapeutic target as it sits on the surface of the bacterium, and our bodies don't use this type of gateway," McDevitt said.