Tricking bacteria into hydroxylating benzene

June 11, 2018, Nagoya University
Tricking bacteria into hydroxylating benzene
Fig.1 Phenol production using bacteria. Credit: Osami Shoji and Masayuki Karasawa

Nagoya University researchers use E.coli to convert benzene into phenol, simplifying a chemical reaction that is difficult by conventional methods

Breaking carbon–hydrogen bonds is notoriously difficult in lab chemistry, yet nature does it effortlessly. Now, scientists have used E.coli bacteria to oxidize the C–H bonds in benzene to generate phenol, with a genetically inserted (cytochrome P450BM3), that originally evolved to target other molecules, long-chain fatty acids.

Getting enzymes to do novel reactions – effectively hijacking the biochemistry of living for our own purposes – is generally tricky, involving harsh conditions or genetic modification of the enzymes themselves.

However, researchers at Nagoya University worked around this by using "decoy" molecules, which mimic the native targets (substrates) of naturally occurring enzymes, to activate the desired reaction.

As reported in Angewandte Chemie International Edition, the research team created a compound – dubbed C7-Pro-Phe – based on amino acids. This decoy molecule resembles the fatty acids that E.coli metabolizes. Insert the decoy into an E.coli cell, and it will be mis-recognized as a fatty acid, triggering activation of the inserted P450 enzyme. Now supply benzene (C6H6), and the bacteria get busy, oxidizing C6H6 to C6H6O (phenol). No need for the usual lab kit – living cells can do complex chemistry quietly and efficiently.

Fig.2 Hydroxylation of benzene using decoy molecules. General catalytic cycle of P450BM3 (black) and a plausible catalytic cycle (blue) for benzene hydroxylation catalyzed by P450BM3 with assistance of the decoy molecule. Credit: Osami Shoji and Masayuki Karasawa
"The advantage of our system is that C7-Pro-Phe can be easily taken up by the bacteria, where it activates P450BM3 in the cell. This effectively turns each bacterium into a whole-cell biocatalyst," study first author Masayuki Karasawa says. "The cell is an optimal setting for the biochemical reaction. The decoys actually remodel the enzyme's active site, giving us control over aspects of the , such as stereoselectivity."

All that is needed is a ready supply of glucose – which can be recycled from waste products – to feed the E.coli.

Because a naturally occurring – rather than genetically modified – variant of the enzyme is expressed by the E.coli, it is likely that other bacteria could also be modified with the same gene to perform this job. Moreover, different decoys might be suitable for different substrates or bacteria. "A combined program of decoy-screening and mutagenesis could create a versatile toolkit for whole-cell reactions using ," co-author Osami Shoji says.

Explore further: New technology for enzyme design

More information: Masayuki Karasawa et al. Whole-Cell Biotransformation of Benzene to Phenol Catalysed by Intracellular Cytochrome P450BM3 Activated by External Additives, Angewandte Chemie International Edition (2018). DOI: 10.1002/anie.201804924

Related Stories

New technology for enzyme design

June 1, 2018

Scientists at the University of Würzburg have chemically modified the enzyme levansucrase using a new method. The enzyme can now produce sugar polymers that are exciting for applications in the food industry and medicine.

Virus genes from city pond rescue bacteria

May 28, 2018

A key question in evolutionary biology is how new functions arise. New research at Uppsala University, Sweden, shows that bacteriophages (viruses that infect bacteria) can contribute to new functions by revealing hidden potential ...

Recommended for you

Field-responsive mechanical metamaterials (FRMMs)

December 11, 2018

In a recent study published in Science Advances, materials scientists Julie A. Jackson and colleagues presented a new class of materials architecture called field-responsive mechanical metamaterials (FRMM). The FRMMs exhibit ...

Researchers develop smartphone-based ovulation test

December 11, 2018

Investigators from Brigham and Women's Hospital are developing an automated, low-cost tool to predict a woman's ovulation and aid in family planning. Capitalizing on advancements in several areas, including microfluidics, ...

CRISPR method for conditional gene regulation

December 11, 2018

A team of engineers at the University of Delaware has developed a method to use CRISPR/Cas9 technology to set off a cascade of activities in cells, a phenomenon known as conditional gene regulation. Their method, described ...

0 comments

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.