Medical Research Council - London Institute of Medical Sciences

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Immune Avengers Assemble

Blood proteins that assemble to create a 'hole-punch' fatal to bacteria seen close-up using electron microscopy

19 October 2018

Immune Avengers Assemble

There are membranes wrapped around all of our cells, and single-celled organisms like bacteria, too. But they do more than just hold everything in – tiny tunnel-like pores control the flow of important chemicals in and out. Usually this delicate balance helps life along. But here is a pore-making protein that can kill. The complement membrane attack complex (MAC) assembles from a group of proteins in our blood, triggered by our immune system to punch holes in nasty pathogens like bacteria – its long strands piercing the cell surface while precious chemicals burst out. Examining the structure of MAC using cryogenic electron microscopy allows scientists to spot a crucial step in how these avenging proteins come together – slotting together a series of identical protein pieces into a ring shape, before it can begin to penetrate the cell. This insight may help the design of drugs to help MAC tackle infections.

Written by John Ankers

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