Scientists expand toolbox to study cellular function

January 4, 2017
Associate Professor Brian Paegel led the study on the Florida campus of The Scripps Research Institute. Credit: The Scripps Research Institute

Scientists on the Florida campus of The Scripps Research Institute (TSRI) have developed a new tool for studying the molecular details of protein structure.

Their new study, published recently in the journal Proceedings of the National Academy of Sciences, explores how evolution can be used to discover new and useful enzyme tools, called proteases.

Proteases cleave proteins into smaller peptide pieces that scientists can then analyze to determine the identity of the protein and whether a cell has made chemical changes to the protein that might alter its function.

The new protease developed in the study helps shed light on these , called post-translational modifications. Post-translational modifications are alterations made to proteins after the proteins are translated from RNA.

"We have to observe these protein modifications directly through chemical analysis; we can't read them out of DNA sequence," explained study senior author Brian M. Paegel, associate professor at TSRI.

These modifications can dramatically alter a protein's stability and function, and unregulated modification can lead to disease, such as cancer. Therefore, understanding the nature and location of these modifications can be critical in the early phases of drug discovery.

Scientists currently rely on a technique called to study post-translational modifications. With mass spectrometry, scientists analyze peptides to see if their mass changes—a bit like zooming in on that protein to see hidden details. An unexpected change in mass can indicate the occurrence of a post-translational modification.

Many scientists today use a protease called trypsin to break proteins into peptides. Because there are few other proteases available for mass spectrometry, trypsin has become the workhorse of the field. However, Paegel explained, it's luck of the draw if trypsin generates a peptide with a modified site. So Paegel and co-workers thought it would be useful to have a new tool that cleaved directly at the modified site.

To solve this problem, Paegel developed a new trypsin "mutant" using a technique called "directed evolution." The scientists created many thousands of trypsin mutants and tested each mutant for its ability to cut a at modified sites. They discovered a mutant that could cut proteins at citrulline, which is one type of modification.

Paegel believes this new approach could be useful for mapping a wider range of post-translational modifications, and he hopes to use directed evolution to discover proteases that target many other post-translational modifications. "I think we're on the brink of an explosion of new tools for mass spectrometry," he said.

Explore further: Scientists develop new toolkit for exploring protein biology

More information: Duc T. Tran et al. Evolution of a mass spectrometry-grade protease with PTM-directed specificity, Proceedings of the National Academy of Sciences (2016). DOI: 10.1073/pnas.1609925113

Related Stories

How plants decide that it is time to flower

December 19, 2016

When spring is approaching, how do plants decide that it is time to flower? A team of plant scientists led by KWAK June M. at the Center for Plant Aging Research, within the Institute for Basic Science (IBS) unravelled a ...

Recommended for you

Male baboons found to engage in feticide

January 18, 2017

(Phys.org)—A team of researchers from several institutions in the U.S., some with ties to the Institute of Primate Research, National Museums of Kenya, has found that male baboons in the wild at times engage in feticide. ...

What humans and primates both know when it comes to numbers

January 18, 2017

For the past several years, Jessica Cantlon has been working to understand how humans develop the concept of numbers, from simple counting to complex mathematical reasoning. Early in her career at the University of Rochester, ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

BubbaNicholson
not rated yet Jan 05, 2017
Wow, we certainly hear a lot about Scripts. Perhaps if they hired more intelligent researchers they might discover something interesting occasionally. Good to see that they're smart enough to hire an excellent publicist though. Perhaps if the publicists did the science it all wouldn't be such a waste of everybody's time?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.