Ancient protein resurrected in bacteria

Engineering an ancestral protein into E. coli makes it virus-resistant.

Viruses often commandeer their hosts’ proteins to turn infected cells into virus factories. Researchers have tried inactivating these proteins to boost virus resistance in plants, but this can harm the hosts. Jose Sanchez-Ruiz and his colleagues at the University of Granada in Spain have developed another way of doing this, using Escherichia coli, which can be infected by a bacteriophage — a bacterial virus — called T7.

The authors focused on one of the bacterium’s thioredoxin genes, which T7 hijacks and uses to replicate during infection. They replaced this gene with one of several ancestral versions that encode forms of the protein that T7 has not encountered before. The team found that a bacterial thioredoxin from about 2.5 billion years ago conferred T7 resistance with minimal effect on the bacterium’s growth.

This method could be used to make crops resistant to viruses, the authors say.