A KNOT has been found in a protein made by a primitive bug called Methanobacterium thermoautotrophicum. While knots in proteins aren’t unheard of, they are still rare. And no one knows how they form or how they affect protein behaviour.
Finding a knot in such an ancient bacterium indicates that they must have some use, says co-author Andrzej Joachimiak from the Argonne National Laboratory in Chicago. “Evolution doesn’t hold on to things it doesn’t need,” he says. Perhaps the knot might help the protein hold together at high temperatures, he suggests (Proteins, vol 50, p 177).
