Helix heresy

摘要

Imagine Dna. Chances are, the double helix leaps to mind. Ever since James Watson and Francis Crick proposed this elegant structure in 1953, the image of two gracefully intertwined ribbons framing the rungs of a spiralling ladder has become the very symbol of DNA. A model of stability and order, the double helix is so firmly established it seems heretical to envision DNA any other way. But growing numbers of researchers are saying there may be much more to DNA than the double helix. It seems DNA can perform all sorts of gymnastic feats, twisting and folding into many different structures and even forming triple helices. Scientists have known about these structures for decades but mostly dismissed them as oddities created in the lab, with no function in living cells. Now, however, more and more evidence suggests these forms not only exist in living cells, but may have crucial roles in an ever-expanding list of human diseases, including the neurodegenerative disease Huntington's and perhaps even autism, schizophrenia and cancer. They may play an important part in our health too, policing the behaviour of our genes and protecting them from damage. DNA may be a lot more dynamic and versatile than once thought, and we are just beginning to understand what that means.