Scientists Discover What Prompts Double-Helix DNA Strands to Open
Scientists have long sought to discover what prompts double-helix DNA strands to open and replicate. Now, researchers at the University of Southern California (USC) in Los Angeles believe they have found the missing piece of this puzzle. As reported in eLife, the team suggests that a ring of proteins that bond with DNA appears to prompt replication.
According to their paper, “The Structure of SV40 Large T Hexameric Helicase in Complex With AT-rich Origin DNA,” the protein rings tighten around the strands, essentially “melting” them to the point where they open and replicate. These findings result from the study of the cancerous SV40 virus, which overtakes the DNA replication process by mimicking proteins that prompt genetic replication in healthy cells. Such understanding may lead to therapies that can block replication of viral pathogens.
In the study, researchers used a helicase from a large tumor antigen associated with the SV40 virus — which is linked to brain cancer, bone cancer, mesothemlioma and lymphoma. Six proteins from the antigen create a helicase that mimics healthy structure. A three-dimensional view of the anatomic structure, obtained via X-ray crystallography, revealed proteins surrounding the DNA had essentially melted the origin DNA — at which point the double helix divided into separate strands. This discovery deepens science’s understanding of how viral pathogens and healthy cells replicate.