Enzymes in cells normally perform only one job, but a new study by a Texas A&M AgriLife Research scientist might figure out how to recruit enzymes for other jobs to benefit medical fields and industry.
“We know that enzymes usually have one biological function in a cell, but many are capable of doing something quite different, when given substrate molecules – those at the beginning of a chemical reaction – that they don’t normally encounter,” said Dr. Margy Glasner, AgriLife Research biochemist in College Station.
Glasner has received more than $767,000 in a five-year grant from the National Science Foundation to study how to make use of the so-called promiscuous enzymes – those that have these hidden abilities in addition to their normal function.
“If mutations improve these hidden abilities, enzymes can evolve new functions that are useful to the organism,” Glasner said. “In some cases, mutations cannot improve the promiscuous activity because the enzyme is an evolutionary deadend.”
The key to the research will be understanding how and why certain enzymes are capable of functioning in new jobs so their ability could be applied to help people and the environment.
Her team is trying to determine why one enzyme can evolve a new function but another, related protein cannot. An enzyme is a protein that speeds up the rate of a chemical reaction.
Her work is part of the basic science which ultimately could have such applications as removing toxins from the environment, Glasner said.
“Bacteria are good at finding ways to degrade even pesticides invented in the 1950s. But we may be overtaxing natural evolutionary processes, given the quantity of such chemicals still in the environment,” she said. “If we understood the mechanism of evolution better, we might be able to design enzymes that can tackle this problem. And because enzymes can work in water and are biodegradable, they could replace toxic chemicals in industrial processes.”
The idea of engineered proteins are not new, she noted. Many laundry detergents already contain proteins that have been made to work better in soap and in hot or cold water. What is different with this work is that the researchers hope to learn more about the “structural and catalytic properties that were required for the evolution of a new function” in enzymes so they can be used to develop new ways to make enzymes carry out new activities, Glasner noted.
She likened current protein engineering technology to retraining a human workforce. In one factory, the people know how to make metal circles and it would not be hard to adapt to making squares.
But in another factory, if the people who are making metal circles have to start making plastic toys, “you need different machinery and training for the employees,” Glasner explained. “That is similar to what we hope to do by discovering how to design enzymes that have the right equipment to take on new roles.”
Source: Texas A&M University