Scientists could sabotage bacteria's cell wall

Scientists from the University of Leeds have pieced together how bacteria build their outer, defensive wall — in essence, the cell’s armour plating — thus heralding a new strategy in the hunt for antibiotics. Their findings have been published in the journal Nature Communications.

The research focused on the role of a protein called SurA. Known as a chaperone, the job of SurA is to martial other proteins from where they are made, at the centre of the cell, to where they are needed — in this case, to bolster the bacterium’s outer wall.

Proteins are long chains of amino acids that must adopt a defined structural shape in order to function effectively. Without the chaperone SurA, the essential proteins needed to build the cell wall run the risk of losing their structural integrity on their journey to the outer membrane.

Using advanced analytical techniques, the scientists mapped how the chaperone SurA recognises proteins to transport them to the bacterial outer membrane.

“For the first time we have been able to see the mechanism by which the chaperone, SurA, helps to transport proteins to the bacterial outer membrane,” said Dr Antonio Calabrese, University Academic Fellow in The Astbury Centre for Structural Molecular Biology, who led the research. “In effect it does this by cradling the proteins, to ensure their safe passage. Without SurA, the delivery pipeline is broken and the wall cannot be built correctly.”

The research team focused on E. coli, a bacteria found in animal and human intestines. But the process they discovered is shared by many pathogenic gram-negative bacteria, a number of which are becoming resistant to antibiotics.

“Understanding that process of how bacteria build their cell wall in greater detail may identify ways we could intervene and disrupt it,” Dr Antonio Calabrese said.

“In doing so, we can either destroy the bacteria altogether or reduce the rate at which they divide and grow, making bacterial infections less severe.”

Professor Sheena Radford, Director of The Astbury Centre for Structural Molecular Biology, said, “This is an exciting discovery in our quest to find weak spots in a bacteria’s armoury that we can target to stop bacterial growth in its tracks and build much-needed new antibiotics.

“It’s early days, but we now know how SurA works and how it binds its protein clients. The next step will be to develop molecules that interrupt this process, which can be used to destroy pathogenic bacteria.”

Dr Calabrese concluded, “We are at the start of a quest that could result in new, drug-based therapies that work either alone or with existing antibiotics to target these disease-causing bacteria.”

Image credit: ©iStockphoto.com/Eraxion

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