Scientists find mechanism behind DNA replication
Researchers from St. Jude Children's Research Hospital have determined the structure of the machinery that drives this process with an atomic resolution image.
Scientists have discovered the mechanism behind the separation of two strands of DNA. DNA stores the genetic information of living organisms. When organisms reproduce, the double-stranded DNA unwinds and separates into single strands to be copied for cell division. Each of the new helix getting copied from the original DNA strand will be composed of the original DNA strand as well as a newly synthesized strand. This process is called Semiconservative Replication.
Researchers from St. Jude Children's Research Hospital have determined the structure of machinery that drives this process with an atomic resolution image. According to one of the researchers working on the project, the new discovery may help in solving one of the greatest mysteries of biology - how double-stranded DNA separates into single strands to start the replication process.
How has this mechanism been found?
DNA gets copied before the cell gets divided for reproduction. This process of making copies of DNA is called replication. An enzyme called minichromosome maintenance or MCM complex plays an important role in this replication process. It is located at the fork where double-stranded DNA separates into single strands.
Before the cell division, the double-stranded DNA is encircled by two separate MCM complex enzymes. Scientists have taken an image of the MCM complex bound to single-strand DNA and the molecules that fuel the process of replication of these DNAs. Since the image has been taken at the atomic level, it shows the orientation of both the MCM complex and single-strand DNA.
According to the image, the process works like a pulley system to 'pull' a single strand of an atom of DNA to unwind it. The MCM complexes begin to move in different directions, leading to the separation of double-stranded DNA into single strands. Scientists suggest that this same mechanism can also tell us about how DNA replication begins.
Eric Enemark, Ph.D. who is an associate member of the St. Jude Department of Structural Biology said, "Based on the crystal structure in this research, we propose that a rotary mechanism drives the transformation to initiate DNA replication. This single event is at the heart of cell division and presents the essence of life in its most streamlined form."
Image Credit: Wikipedia