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Supercoil me!

Even living cells have their own tangled problems to solve. They involve knots that arise accidentally in DNA and that can comprise its functionality. A new study by SISSA (Scuola Internazionale Superiore di Studi Avanzati) brings a new twist to the problem and suggests that the DNA propensity to be supercoiled, just like telephone cords, can come to the rescue. These coils can keep DNA knots locked in place for long enough that they can be untied by specialised enzymes. The computational study, based on molecular dynamics simulations of bacterial DNA, has just been published in Nucleic Acids Research . A tangled problem Supercoiled, twisted, and even knotted! Far from the elegant and polished textbook images, DNA filaments in living cells is all crumpled and entangled and, to be functional, needs to be constantly unravelled, much like our telephone cords that with careless use accumulate annoying curls or supercoils. "Supercoils are, in fact, present in DNA too ...
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Fussy eaters: the favoured food of Salmonella

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As antibiotic resistance increases the search for new anti-bacterial treatments becomes more and more important. One way to design anti-bacterials is to find specific biochemical pathways that the bacteria require to survive, and develop drugs that block off these pathways. Some pathways are better targets than others and for  Salmonella bacteria it was thought that pathways dealing with nutrient metabolises would be a lost cause. Salmonella lives in the intestine, which hosts a whole variety of different nutrients, so surely preventing the bacteria from using a specific one wouldn’t cause them much undue distress. It’s been found, however, that as they grow and spread in the inflamed intestine the bacteria are heavily reliant on one particular nutrient: fructose-asparagine. The chemical structure of fructose-asparagine, image from the reference. The importance of fructose-asparagine metabolism was originally discovered durin...
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New approach to treating infectious diseases as an alternative to antibiotics

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Enterotoxigenic Escherichia coli (ETEC) is known as a major cause of diarrhea in travelers and people living in developing countries. According to the World Health Organization (WHO), ETEC is responsible for 300,000 ~ 500,000 deaths a year, constituting a serious problem. Effective vaccines for ETEC have not been developed, so patients infected with ETEC are treated with antibiotics and supporting measures. However, the emergence of multidrug-resistant bacteria has become a social issue, so the development of new treatment methods is sought after. Adherence to the host intestinal epithelium is an essential step for ETEC infection in humans. It was thought that a filamentous structure on the surface of bacteria called 'type IV pilus' was important for bacterial attachment, but its detailed adhesion mechanism was not known. Osaka University-led researchers clarified how pathogenic E.coli attached to the host intestinal epithelium using type IV pili and secre...
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