An international team of scientists, led by researchers from the University of St Andrews in the UK and Guelph in Canada, has used cutting-edge X-ray and ultraviolet light studies to reveal the workings of the molecular ruler that helps bacteria to survive and outsmart the human immune system.
The research findings represent a significant step forward in our fundamental understanding of biology. Although the concept that biology can control the length of polymer chains using a molecular ruler dates back to the early 1970s, the ruler itself has never been visualised by scientists at the molecular level. These careful control mechanisms are commonly found in nature. Prof James Naismith from the University of St Andrews explained the significance of this work, “The molecular ruler, which we’ve shown to be a rigid coiled-coil protein/protein complex, is critical as without it bacteria have no idea when to stop producing the long polymers that are attached to their outer membranes. The length of these sugar polymers is controlled in the same way as curtain makers pull and measure their rolls of fabric before deciding where to make their cut. It is a beautiful and elegant demonstration of form and function.”
When humans or animals are invaded by bacteria, the body does its best to go on the counter attack and provide a natural immune response that will make us well again. If this doesn’t work, we turn to the medical profession for drugs. Combating infection and disease is a tricky business, as the invaders invariably have a host of tricks up their sleeve to thwart us. One of these tricks involves using these sugar polymers to protect themselves against us.
Prof Naismith continued, “This project involved scientists from St Andrews, along with collaborators from Germany, Canada and Diamond Light Source. We used a combination of experimental techniques at Diamond, the UK’s national synchrotron science facility, and the European Molecular Biology Laboratory (EMBL) in Germany, to piece together the structure of this molecular ruler, and crucially to prove that it is possible to change the length of it and, in doing so, change the length of the polymer. This opens up a new avenue of research whereby we can look to design drugs that interfere with the ruler. The work gives chemists something to aim for, the elegant solution to controlling polymerisation: a problem in many industrial processes.”