Living cells, unlike ambivalent suitors, need not be told, “If you liked it, you should have put a ring on it.” No, when the cell starts to divide, it places a ring of proteins around a specific site on
These events are now known in greater detail thanks to new work carried out by a team of researchers based at the University of Southern California (
Details appeared December 6 in the journal eLife. In an article entitled, “The Structure of SV40 Large T Hexameric Helicase in Complex with AT-Rich Origin
“[The] co-crystal structure of the SV40 Large-T Antigen (LT) hexameric helicase bound to its origin dsDNA,” wrote the authors of the eLife article. “The structure shows that the six subunits form a near-planar ring that interacts with the origin, so that each subunit makes unique contacts with the
The helicase’s domain channel narrows and compresses the double-stranded (ds)
After origin melting occurs, the double helix divides into separate strands. These
“Understanding the mechanisms of origin
Dr. Chen emphasized that the origin
To prompt replication, Dr. Chen’s team used a helicase from a “Large Tumor Antigen” or Large T. The antigen comes from the SV40 virus linked to human cancers, such as brain and bone cancers, mesothelioma, and lymphoma. The six proteins from Large T comprise a “helicase” that mimics the structure of the healthy cells’ helicases.
Next, the scientists obtained a 3D view of the atomic structure of the helicase using X-ray crystallography. The images the scientists obtained revealed that the proteins surrounding the
Although the scientists used a cancer-causing virus to study replication, healthy cells replicate in a similar way, Dr. Chen indicated.