![]() ![]() "We've done a similar thing with replisome. That allows them a more detailed look at specific parts that can't be tested in a moving car. "To do that, engineers might remove the engine and bench test it. "If you think of the replisome as a car, it's a complete functional system, but we can't really test the more intricate parts of the engine," Dr Spenkelink said. SSB strand transfer and the Escherichia coli replisome. Coli bacteria to visualise at single-molecule resolution SSB behaviour as DNA replication happens. Molecular Horizons researchers extracted an active replisome from E. While this has provided general insights into the interaction between the two, they have not shown how SSBs work in the context of the complete DNA replication process inside the replisome. ![]() Previous studies have used short strands of DNA and SSBs in isolation. Though errors are rare, occurring at a rate of 1 mistake per million base pairs, one mistake that slips past the repair mechanisms can produce a DNA sequence that, if it survives and avoids the body's defence mechanisms, could also survive drug treatments and eventually become a superbug.Īs a result, understanding SSBs' role is crucial in understanding disease and antimicrobial resistance. The wrong enzyme means the DNA sequence – the series of letters or base pairs that form a genetic code – could be mismatched, resulting in a mutated DNA sequence. ![]() The other strand, called the lagging strand, is momentarily exposed because the processes of unzipping the helix and copying the genetic information run in opposite directions.Īddressing the second threat, SSBs also help coordinate DNA copying and avoiding mistakes that could lead to mutations by regulating which enzyme is used to prepare the strand for copying. This information comes from replicating the parent cell's DNA and transmitting it to the new cell.Īs the double-helix DNA unwinds into two strands, one strand, called the leading strand, is copied and formed into a new double helix almost as soon as it's unzipped. When a cell divides, it produces two 'daughter' cells that must contain the same genetic parent information to be able to carry out its required function. What we have revealed is a dynamic and highly efficient process that adapts to its surrounding conditions." "Until now it hasn't been shown exactly how SSBs are used. "DNA replication is elegant but inside the replisome is a cramped and messy place," lead researcher Dr Lisanne Spenkelink said. The replisome can adapt how it uses SSBs according to how much is available. The Molecular Horizons work has for the first time revealed the complex molecular choreography where both processes occur. ![]() Until recently, it was unclear how SSBs were used in the replisome, the 'factory' or molecular complex that copies DNA, with two models suggesting the protein is either available from the cytosol, the aqueous solution in the cell, or the protein is in finite supply and recycled continuously. Single-stranded binding proteins (SSBs) support DNA replication by protecting single-stranded DNA and coordinating, or regulating, the enzymes used to copy the DNA in the correct genetic sequence. ![]()
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