Reprogramed nonribosomal peptide synthetase incorporates amino acids with reactive sites for “click” chemistry
A single targeted mutation is enough to alter a natural peptide system so that it also incorporates non-natural amino acids into peptides, report Swiss scientists in the journal Angewandte Chemie.
The mutation increases the size of the binding cavity in one domain of the system, which changes the substrate specificity. The researchers are thus able to incorporate amino acids with a specific reactive group that can later be used to easily modify the peptide.
In the search for new pharmaceuticals through the use of combinatorial chemistry and screening processes, researchers are often faced with the task of modifying and varying natural substances—sometimes by adding further molecular components, for example.
Highly specific coupling with molecular markers is particularly important because it allows scientists to monitor the distribution of natural substances in cells and tissues. Coupling reactions that are almost as snapping components together can be carried out by a technique known as “click chemistry”. This method encompasses broadly applicable reactions like those between alkynes and azides, which deliver high yields.
For this technique, the natural substance must first be equipped with such an alkyne or azide group. One way to achieve this would be through the incorporation of amino acids with alkyne or azide side chains into proteins through alteration of their biosynthesis.
However, many interesting natural substances, such as the gramicidin antibiotics, are not formed by way of the classical pathways of protein biosynthesis through the reading of genes and the assembly of amino acids in the ribosomes. Instead, they are made by nonribosomal peptide synthetases, very large multi-enzyme complexes whose individual modules hang together like pearls on a necklace.
These activate the amino acid building blocks and incorporate them into the growing peptide chain. The number, type, and ordering of the individual modules determine the length and composition of the resulting—usually short-chained—peptide. In addition to the usual amino acids, it is also possible to incorporate other, sometimes unusual, individual building blocks, which allows for the formation of an astonishingly large variety of peptides.
Researchers working with Donald Hilvert at the ETH in Zurich exchanged an individual amino acid in one module of the nonribosomal production apparatus for the antibiotic gramicidin S through a mutation. This altered an area known as an A domain, which specifically recognizes and activates the natural amino acid phenylalanine.
The mutation causes the binding cavity to be roomier, so that non-natural amino acids that contain an azide or alkyne group can be activated and incorporated into the peptide chain in place of phenylalanine. The catalytic activity of the overall system is not affected by this change in selectivity.
Because many different nonribosomal synthesis systems contain such A domains, this new method is potentially a general approach for equipping important natural substances with a reactive site for highly specific covalent modification.
About the Author
Dr. Donald Hilvert is Professor of Chemistry at the ETH Zürich. His research group is investigating how enzymes work and evolve and applying this knowledge to the design of new protein-based catalysts. These efforts have been recognized by a number of awards, including the Pfizer Award in Enzyme Chemistry and the Emil Thomas Kaiser Award from the Protein Society.
Author: Donald Hilvert, ETH Zürich (Switzerland), http://www.protein.ethz.ch
Title: Reprogramming Nonribosomal Peptide Synthetases for "Clickable" Amino Acids
Angewandte Chemie International Edition, Permalink to the article: http://dx.doi.org/10.1002/anie.201405281
Donald Hilvert | Angewandte Chemie - Wiley
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences