Synthetic switch-in-a-cell ‘electrifies’ live bacteria.
Bioelectronics is the application of the principles of electronics to biology, being described as the research and development of bio-inspired electronic architectures down to the atomic scale in inorganic, and organic materials. Therefore giving natural biological structures electrical properties without the use of electrical components is seen as the next step in bioelectronics and is highly desirable. Now, a study from researchers at Rice University uses synthetic biology to develop artificial electrical switches built from a protein to control the flow of electrons into a cell. The team state the proteins could facilitate next-generation bioelectronics, including complete biological circuits within cells which mimic their electronic counterparts; the possible applications include living sensors, electronically controlled metabolic pathways for chemical synthesis and active pills that sense their environment and release drugs only when needed. The study is published in the journal Nature Chemical Biology.
Previous studies show natural proteins which move electrons are seen to act as wires that are always there. Nature typically controls electron flow by using genetic mechanisms to control the production of these protein-based wires. Using transcriptional genetics, even in a fast-growing E. coli bacteria, it takes many minutes to produce and control these ‘wires’; by contrast, protein switches function on a time scale of seconds. The current study develops ferredoxin logic gates in E. coli bacteria to control energy flow through a synthetic electron transfer pathway which is required for bacterial growth.
The current study uses ferredoxin, a common iron-sulfur protein which mediates electron transfer, as the foundation for the switch embedded in a synthetic mutant strain of E. coli. Results show that the switch can be turned on in the presence, or off in the absence, of 4-hydroxytamoxifen, an estrogen receptor modulator, or by bisphenol A, a synthetic chemical used in plastics.
Data findings show that the ferredoxin switch acquires an electron cluster and can use different chemicals to control the production of a reduced metabolite in the E. coli. The lab explain that their E. coli bacterium is a mutant strain programmed to only grow in a sulfate medium when all of the components of the ferredoxin electron transport chain, including electron donor and acceptor proteins, are expressed; in that way the bacteria can only grow if the switches turn on and transfer electrons as planned.
The team surmise they have developed synthetic protein switches triggered by chemicals, which can ‘electrify’ a living cell. For the future, the researchers state that their data should lead to custom-designed switches for many applications, including contact with external electronic devices.
Source: Rice University