THE twists and bumps on stretches of non-coding DNA could give clues to what they are there for.
The DNA that codes for proteins makes up only 2 per cent of the human genome. Other functions, such as switching on genes, are embedded somewhere in the remaining 98 per cent. One way to home in on the functional areas is to scan for sequences that humans share with other mammals, suggesting they have been conserved for a reason.
But of Boston University and his colleagues wondered whether different sequences might show up if they looked instead at the DNA鈥檚 outward shape. DNA鈥檚 complex chemistry means two similar sequences can produce very different outer shapes, while two different sequences can have similar shapes.
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The team used a computer program to predict the outer shape of a genome from its base pairs. When they compared the shape of the human genome with the genomes of 36 other mammals, 50 per cent more DNA appeared conserved than if they just took account of sequence (Science, ).
Shape could indicate function because it helps determine whether proteins can bind to and activate a stretch of DNA, says Tullius.
