When excited by laser beams, proteins inside jellyfish glow a bright fluorescent light. Photo by University of York
June 27 (UPI) -- Scientists have developed a more effective way to highlight and watch the molecular machinery inside a cell. Using fluorescent biomarkers, researchers successfully observed the replication of DNA inside a bacteria cell.
Researchers assumed the bacteria cell would divide like most others, slowly making a copy of every cellular component -- including DNA -- inside the cell wall before dividing and dislodging the replica.
When researchers watched the process in real-time, they observed a more complex and seemingly disjointed order of events. The findings showed only one cellular component, DnaB helicase, remains stable during the process. The enzyme serves as a molecular anchor for the replication process.
"Our data challenges the widely-accepted semi-discontinuous model of chromosomal replication, instead supporting a fully discontinuous mechanism in which synthesis of both leading and lagging strands is frequently interrupted," researchers wrote in their paper, published this week in the journal eLife.
Scientists were able to watch the replication using proteins found inside jellyfish. Researchers engineered bacteria cells with the fluorescent proteins attached to important molecular machinery. When laser beams are focused on the cells, the scientists were able to watch the movements of the molecular machinery during the genetic replication.
"We pioneered a new method of light microscopy which allowed us to see this fascinating replication process occur molecule-by-molecule," Mark Leake, a biological physicist at the University of York, said in a news release.
Researchers believe the stuttering-like manner in which DNA is divided and copied allows the cell to double-check the replication.
"The stuttering action provide 'checkpoints' at various stages of the DNA copying process to make sure there is no errors made and, if there is, correct them before it is too late," Leake said. "This means that the cells can pause to fix an error in a small fragment of the DNA rather than attempt an unmanageable correction in one complete and huge strand of it. Although the process looks inelegant and almost random, it is actually highly efficient."
The process, researchers found, is much more dynamic than previously realized. Scientists hope their continued study of DNA replication can help them better understand how mistakes occur, as well as how they're fixed. Understanding coding errors could help scientists develop treatments for diseases caused by genetic defects, including cancer.