By trying to speed up, molecular processes can become more reliable 鈥� a phenomenon that may have helped life evolve from relatively simple chemicals. Understanding how speed plays a role in cellular replication could add a crucial variable to Charles Darwin鈥檚 theory of evolution, in which natural selection drives reproductive success.
The finding comes from at University College London, at the University of Chicago and their colleagues, who were frustrated by an experiment that defied their intuition. They were studying an enzyme called DNA polymerase, which helps copy strands of DNA, keeping track of how fast it worked and the number of mutations that arose from its errors.
They found that different versions of the enzyme didn鈥檛 always work at the same speed, but those that copied most quickly also made the fewest errors. This was completely counter to what they expected 鈥� they had assumed that enzymes that are more accurate would be slower since it takes time for them to 鈥減roofread鈥� and correct errors, just as it takes time for people to do this. To see if this phenomenon was unique to DNA polymerase, the researchers modelled other cellular processes. They simulated a self-replicating cell that must assemble its internal structures before it can divide. Like the initial finding, its fastest assembly process had the fewest errors.
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The team produced a mathematical model that suggests that any self-replicating system should behave similarly, says Ravasio. He says he and his colleagues think this phenomenon may be at play in many systems in nature that benefit from self-correction including everything from internal cell processes to bees searching for food.
The finding shows that the systems evolve the right structure just by naturally aiming to grow quickly, without a 鈥渟ense of a 鈥榬ight鈥� and 鈥榳rong鈥� output鈥�, says at the University of Michigan, who was not involved in the research.
鈥淚t鈥檚 sort of a free lunch, you get some order, and it speeds you up,鈥� says co-author at the University of Chicago.
Both Murugan and Shankar think this observation may help decipher a key question regarding life鈥檚 origins: how relatively simple molecular machines managed to build increasingly complex cells.
arXiv
