Shigella, a bacterial infection that causes dysentery and is the major cause of diarrheal diseases in children, penetrates an infected person’s intestinal cells via a channel called a translocon and then injects bacterial proteins into the cells.

The proteins then use the cells’ machinery to boost Shigella’s growth.

A team from Massachusetts General Hospital (MGH) discovered vital insights about Shigella’s translocon in a paper published in mBio, which could enable researchers in developing an effective strategy to inhibit this critical component of infection.

“Shigella infects our gut by manipulating our intestinal cells and tricking them into letting the Shigella inside. In fact, there are many bacterial pathogens that use this same, or similar, mechanism to infect us,” said lead author of the study Poyin Chen, PhD, a postdoctoral fellow at MGH.

“This translocon pore is essentially the gateway through which bacterial proteins get pumped into our cells. We know that this structure is made of two proteins—IpaB and IpaC—but what we don’t know is how these proteins fit together to make this pore.”

While studying translocons implanted in cell membranes, researchers were able to identify which of the two proteins—specifically IpaB–makes up the inner ring of the pore using protein mapping techniques.

“If you think of the translocon pore as a donut, this would be the walls of the donut hole. This finding is important because this is the part of the translocon pore that directly interacts with bacterial proteins as they are injected into our cells,” explained Chen.

“With the findings from this study, we can begin to understand if this pore acts as a slippery tube that bacterial proteins travel through or if the translocon pore can control the flow of bacterial proteins into our cells.”

Such information could help researchers in identifying the translocon and preventing Shigella proteins from entering cells.

“For something that is so essential to establishing infection, we know terribly little of how it’s made and how it works,” says Chen.

“As we gain a better understanding of its parts, we will be able to approach the structure as a whole and maybe even find ways to neutralize the function of this structure to prevent infection before it can begin.”

Image Credit: Getty

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