Switch-in-a-Cell Electrifies Life

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Their E. coli bacterium is a mutant strain that is 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. That way, the bacteria could only grow if the switches turn on and transfer electrons as planned.

Silberg said the discovery should lead to custom-designed switches for many applications, including contact with external electronic devices. “It’s why we’ve been so gung-ho about this idea of bioelectronics, a whole field that’s emerging as synthetic biology gets more control over the design,” he said. “Once you can standardize this, there are all kinds of things we can build with cells.”

That could include smart pills that release medications only on demand, or gut biome detectors that report on conditions. Or perhaps electrical circuits contained entirely within cells.

“We can already map a lot of what electrical engineers do with capacitors and resistors onto metabolism, but until now, there have been no switches,” Silberg said.

He suggested multiple switches could also turn a cell into a biological processor. “Then we could see digital parallel processing in the cell,” he said. “It changes the way we look at biology.”

The discovery fits with a new initiative led by Silberg and bioscientist and co-author George Bennett and their colleagues to promote training in the field of bioelectronics. Rice recently received National Science Foundation (NSF) support to start a graduate-level bioelectronics program to be administered by the Institute of Biosciences and Bioengineering. It was also part of the discussion at this year’s bioelectronics-focused De Lange Conference earlier this month at Rice and will be a focus of the Gordon Research Conference co-chaired by Silberg and Rafael Verduzco of the Chemical and Biomolecular Engineering department at Rice, in New Hampshire in June 2019.

Co-authors are biosciences graduate students Ian Campbell and Emily Thomas at Rice and graduate student Sheila Bonitatibus and Sean Elliott, a professor of chemistry, at Boston University. Bennett is the E. Dell Butcher Professor of Biochemistry and Cell Biology at Rice.

The Office of Naval Research, NASA, the Department of Energy and the NSF supported the research.

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