When Yan (pronounced “yen”) Wang joined MJ Bioworks five years ago, her interest in improving enzyme efficiency looked like it would remain a hobby as she took on MJ’s other projects. But in less than six months, she had introduced a promising idea for an enzyme that would bind better and speed up PCR. A year later, recalls her manager Peter Vander Horn, “we completely switched our project portfolio” to work on what he calls “Yanzymes.”
Wang had homed in on processivity as a culprit for poorly performing PCR in her postdoc days at Christine Guthrie’s University of California, San Francisco, lab. She knew that if the enzyme could bind more tightly to the DNA template, it could improve both the speed and accuracy of the amplification reaction. Looking for a relatively small, thermostable protein that would bind to DNA no matter what the sequence is, Wang “identified a DNA binding protein from the thermophilic archaea species Sulfolobus solfataricus,” she says.
She attached it to a few different forms of Taq and each time got a 10-fold improvement in processivity. “Still, we were kind of skeptical about how this increase … would have an impact on PCR,” she says. Wang and her team put the enzyme through more and more tests, each time getting longer amplicons in less time than with regular Taq. According to her calculations, the enzyme performed three times faster than Taq and could amplify fragments up to 30 KB in length.
Another perk was that the modified enzymes “seem to be much more forgiving of the reaction conditions,” Wang says. Her protein, Sso7d, could withstand higher concentrations of inhibitors such as salt and Syber green than most polymerase enzymes.
Meanwhile, Vander Horn was working on his own enzyme project. His protein engineering tweak stabilized the exonuclease-to-polymerase ratio, making the proofreading enzyme more effective. Paired with Wang’s creation, Vander Horn says, the new enzyme — dubbed Phusion and sold by MJ Research — is accurate, quick, and has become “our fastest-growing product line.” Internal research is continuing. “We’re right now working on trying to get to 100 KB [amplicons],” he adds.