Microcosm: E. coli and the New Science of Life

E. coli has acquired much of its resistance to antibiotics from other species of bacteria, which can trade genes like business cards. These discoveries are significant not only because they may help in the battle against drug-resistant pathogens. They may also reveal forces that have been shaping life for the past 4 billion years.

But FliA is also controlled by another protein, called FlgM. It grabs new copies of FliA as soon as E. coli makes them, preventing them from switching on the flagella genes.

Woese did his work years before scientists could easily read the sequence of RNA or DNA. So he and his colleagues did the next best thing: they sliced up Escherichia coli’s 16S rRNA with the help of a virus enzyme.

E. coli uses many tricks to dodge antibiotics. As Florey and Chain discovered, it can secrete enzymes that cut penicillin into harmless fragments. In some cases, E. coli’s proteins have taken on new shapes that make it difficult for antibiotics to grab them. And in other cases, E. coli uses special pumps to hurl antibiotics out of its interior. For

our genomes carry the information necessary for the stately development of a new trillion-celled body complete with 200 cell types and dozens of organs.

A number of essential human genes, which help build things as different as antibodies and placentas, evolved from virus genes.

scientists to work out many of the details. The lactose-digesting genes are lined up

Meselson and Stahl then ran a second version of the experiment. They moved some of the heavy-nitrogen E. coli into a flask where they could feed on normal nitrogen, with only fourteen neutrons apiece. The bacteria had just enough time to divide once before Meselson and Stahl tossed their DNA in the centrifuge. If Watson and Crick were right about h

Along with beta-galactosidase, E. coli makes the protein permease, which sucks lactose molecules into the microbe. When a reluctant E. coli’s lac operon switches on briefly, some of these permeases get produced. They begin pumping more lactose into the microbe, and that extra lactose can pull away more repressors.