Flips and Curls

You might object to someone impersonating you, and intervene to stop a nefarious mirror version of yourself from marauding around your neighbourhood. Such is the body’s response to some instances of Z-DNA – a flipped form of DNA with a left-handed helix instead of the usual right-handed 'B-DNA' conformation. Antibodies against Z-DNA are common in autoimmune conditions such as lupus, and bacterial infections may help provoke these responses. A study investigating bacterial biofilms formed by Salmonella found high levels of Z-DNA. In mice they found that this DNA stimulates a strong anti-Z-DNA immune response, especially when bound to a tough biofilm fibre called curli amyloid fibre (pictured, Z-DNA stained dark blue in a Salmonella (green) biofilm, with pink curli fibres). The findings suggest that bacterial biofilms might contribute to autoimmune responses by providing a previously unseen source of Z-DNA.

Written by Anthony Lewis

Anthony Lewis

Writer

Ant was the web editor in the early days of BPoD, and has since worked with the UK’s top science organisations as a writer and multimedia producer. He now splits his time between freelance work and managing multimedia at The Lancet.

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• Image from work by Molly Elkins and colleagues
• Center for Microbiology and Immunology, Temple University Lewis Katz School of Medicine, Philadelphia, PA, USA
• Image originally published with a Creative Commons Attribution 4.0 International (CC BY 4.0)
• Published in PLOS Pathogens, July 2026