How plant-rotting bacteria steal iron to survive
In a new study, researchers have uncovered important new information about the survival mechanism of bacteria that cause rot in certain plants, including some extremely invasive weeds. The study, published Aug. 2 in the open access journal PLOS Biology, shows for the first time in a precise way how the bacterium Pectobacterium gets iron essential to its survival and its replication: by pirating it from protein containing iron present in the host plants. The study was led by Dr. Rhys Grinter and Professor Trevor Lithgow at the Institute of Biomedicine Discovery at Monash University. The team used comparative genomics to scientifically track the origins of an enzyme, called FusC, which has proven to be the key factor in the import and acquisition of iron.
The authors propose that plant ferredoxin, a protein loaded with iron, is imported into the bacterial cell via a membrane channel called FusA; when it gets inside the cell, the FusC catches it and dismounts the ferredoxin to release the iron. "This is the first example of a bacterium taking a protein from its host, which is important in the bacterial cell and then transforming it inside the cell," said Dr. Grinter. Pectobacterium is of increasing scientific interest for its potential as a biological control agent against invasive weeds such as Allium triquetrum (beveled onion), which can stifle native terrestrial flora such as orchids, lilies and grasses, leaving large infested areas devoid of natural vegetation.
"Knowing exactly how the bacterium gets iron adds to the knowledge needed to maximize the potential of Pectobacterium as a biocontrol agent," said Dr. Grinter. The study also reveals new knowledge about the evolution of this bacterium, discovering that it "re-evolved" the mechanism of import of iron in a parallel way to the import routes of proteins developed in the mitochondria and chloroplasts, the energy centers of plant cells.
"Rhys' work is a remarkable example of how fundamental discoveries in the biological sciences have a tremendous impact," said Professor Trevor Lithgow, lead author. "The study elucidates not only the mechanism by which this bacterium imports iron-laden proteins, with its obvious practical applications, but also reveals a new paradigm on how bacteria develop protein transport pathways in general. This includes bacteria that infect humans and animals. , not just plants, "he said.
