Researchers reveal new details about a key enzyme that makes DNA sequencing possible. The finding is a leap forward into the era of personalized medicine when doctors will be able to design treatments based on the genomes of individual patients.

«Enzymes make life possible by catalyzing chemical transformations that otherwise would just take too long for an organism,» said Greg Weiss, UCI professor of chemistry and a co-corresponding author of the new study. «One of the transformations we’re really interested in is essential for all life on the planet — it’s the process by which DNA is copied and repaired.»

The molecule the UCI-led team studied is an enzyme called Taq, a name derived from the microorganism it was first discovered in, Thermos aquaticus. The molecule the UCI-led team studied is an enzyme called Taq, a name derived from the microorganism it was first discovered in, Thermos aquaticus. Taq replicates DNA. Polymerase chain reaction, the technique with thousands of uses from forensics to PCR tests to detect COVID-19, takes advantage of Taq.

The UCI-led team found that Taq, as it helps make new copies of DNA, behaves completely unlike what scientists previously thought. Instead of behaving like a well-oiled, efficient machine continuously churning out DNA copies, the enzyme, Weiss explained, acts like an indiscriminate shopper who cruises the aisles of a store, throwing everything they see into the shopping cart.

«Instead of carefully selecting each piece to add to the DNA chain, the enzyme grabs dozens of misfits for each piece added successfully,» said Weiss. «Like a shopper checking items off a shopping list, the enzyme tests each part against the DNA sequence it’s trying to replicate.»

It’s well-known that Taq rejects any wrong items that land into its proverbial shopping cart — that rejection is the key, after all, to successfully duplicating a DNA sequence. What’s surprising in the new work is just how frequently Taq rejects correct bases. «It’s the equivalent of a shopper grabbing half a dozen identical cans of tomatoes, putting them in the cart, and testing all of them when only one can is needed.»

The take-home message: Taq is much, much less efficient at doing its job than it could be.

Story Source: Materials provided by University of California — Irvine. Note: Content may be edited for style and length.