A team led by Purdue University biologists explained how a pair of proteins from the bacteria Legionella pneumophila, which causes Legionnaires disease, alters a host protein in order to divert raw materials within the cell for use in building and disguising a large structure that houses the bacteria as it replicates.
Zhao-Qing Luo, the associate professor of biological sciences who headed the study, said the modification of the host protein creates a dam, blocking proteins that would be used as bricks in cellular construction from reaching their destination.
The protein "bricks" are then diverted and incorporated into a bacterial structure called a vacuole that houses bacteria as it replicates within the cell. Because the vacuole contains materials natural to the cell, it goes unrecognised as a foreign structure.
"The bacterial proteins use the cellular membrane proteins to build their house, which is sort of like a balloon," Luo said.
"It needs to stretch and grow bigger as more bacterial replication occurs. The membrane material helps the vacuole be more rubbery and stretchy, and it also camouflages the structure. The bacteria is stealing material from the cell to build their own house and then disguising it so it blends in with the neighbourhood," he explained.
The bacterial proteins involved are AnkX and Lem3, and they modify the host protein through a biochemical process called phosphorylcholination that is used by healthy cells to regulate immune response.
Their work has been published in the current issue of the Proceedings of National Academy of Sciences.