Every time a cell divides, its genomic DNA must be completely, accurately and rapidly duplicated. This feat is completed by an amazing, multi-enzyme nanomachine, called the replisome. The replisome includes one DNA helicase, one RNA polymerase and three DNA polymerases, as well as numerous non-enzymatic proteins, all of which work together at the DNA replication fork. In Part 1a, Dr. Bell gives an excellent, step-by-step description of the function of each replisome protein at the bacterial replication fork.
In Part 1b, Bell focuses on the initiation of DNA replication. At the site where replication begins, chromosomal DNA is separated into two single strands. Two replisomes are then assembled on the DNA and they move away from each other in opposite directions. Bell describes how the sites for the initiation of replication are identified, how the helicase is loaded and activated, and how the replisome is assembled. As he explains, these events are significantly more complicated in eukaryotes than bacteria.
In his last talk, Dr. Bell describes an assay developed in his lab to study eukaryotic DNA replication at the single molecule level. Using this assay, Bell’s lab has determined the detailed process by which eukaryotic DNA helicase loads on DNA and begins the replication process.
Dr. Bell is Professor of Biology at the Massachusetts Institute of Technology and an Investigator of the Howard Hughes Medical Institute. His lab studies the assembly of multi-protein complexes called replisomes that are responsible for replicating eukaryotic chromosomal DNA, and the regulation of this process to ensure that each chromosome is accurately and completely replicated… Continue Reading