University replicates antibiotic

By Christine Kim

For more than 70 years, the presence of nisin, a natural antibiotic used in the food industry, has been acknowledged, yet no one has been able to create it.

However, in late April 2005 University professors Wilfred van der Donk and Satish Nair and graduate students Bo Li and John Paul J. Yu finally created nisin in a test tube and identified its structure.

Their creation was recently recognized in the March 10 edition of Science. Now, after almost a year of trying to refine the system, van der Donk and Li now have preliminary results, but are trying to figure out the details of the raw data.

The creation of the antibiotic opened a new door in refining the system and studying its mechanisms to create new and better antibiotics that can eventually be used in humans.

Nisin is not used for infections in humans because the body breaks it down too quickly through digestion. The goal is to make it suitable for humans to use.

Get The Daily Illini in your inbox!

  • Catch the latest on University of Illinois news, sports, and more. Delivered every weekday.
  • Stay up to date on all things Illini sports. Delivered every Monday.
Thank you for subscribing!

“The more you find out, the better you can tweak it,” said Li, graduate student. “But our main goal is to make better antibiotics.”

Nisin has a unique feature that kills bacteria in three different ways and has multiple modes of action, making it harder for bacteria to develop a resistance to nisin. If a compound kills bacteria in one way, the bacteria will eventually find its way around it. Nisin has been used in the food industry for 40 years without any bacteria showing resistance to it.

Creating nisin is a three-step process. Van der Donk has been working on the first step since 1997, until he read that BiOMaDe Technology Foundation, a company in the Netherlands, engineered a bacterial Lactococcus strain that produces a substrate that could be used for the enzyme cyclase. This allowed the recreation of a process that normally occurs in a strain of bacteria found in milk and allowed a way to use nature’s ways to accomplish the first step.

“Since our group has been working on the project for a while . initially I wasn’t sure if a newer strategy was going to work,” Li said.

Li completed the second step of purifying the enzyme from the medium the bacteria had been growing on. The last step was to cleave off a piece that is inactive against bacteria. While it takes more than 60 steps to create nisin using organic chemistry, nature allowed the team to create it with just two enzymes and three steps.

“We’re hoping to make something better than nisin to combat things in humans,” said van der Donk.

The work was done in collaboration of two groups: van der Donk and his graduate students, who focused on the creation of nisin and the enzyme activity that makes nisin; and Nair and his group of graduate students, who focused on the visual, three-dimensional structure.

“Our main goal is to improve the efficiency of the molecule and the stability,” said van der Donk. “So if we know what the enzyme looks like we have a much higher chance in achieving it . both are important . but the work is quite different.”

Van der Donk asked Nair, professor in biochemistry, to collaborate with him to focus on the structures of the enzymes. Nair uses X-ray crystallography, a method of having small molecules create crystals for a three-dimensional visual and hitting it with an x-ray to create the image.

“Even before I accepted the position in the Chemistry Department, I was interested (in this project),” Nair said.

Now that Nair and Yu identified the structure of nisin, the next goal is to try and capture pictures of the enzyme while it’s carrying out the chemical reaction.

Van der Donk is now in the Netherlands on sabbatical, working in the lab that discovered the mode of action of nisin.

“Since now we know how to make analogs for nisin . I’m learning here how they are working and if they do work better, why they work better,” van der Donk said. “We are interested in how it works in nature so we can use nature’s tools to make derivatives and start looking at stability and their activity.”