Transcriptional segregation

Bacterial genetics was meant to be easy. But, genetics or no genetics, the identity of the motor for segregating bacterial DNA remained a mystery. “People should have found it,” says Jonathan Dworkin. “It's something that is relatively easy to score for.”

Dworkin and Richard Losick (Harvard University, Cambridge, MA) now claim that the motor has never been found before because it is RNA polymerase. “You use a common mechanism to drive [segregation]—we like the parsimony of that,” says Dworkin. “But one of the things that is appealing about the model also makes it difficult to test”—and impossible to discover by genetics.

Dworkin and Losick have tested the model by direct chemical inhibition of RNA polymerase. They found that the segregation of bacterial chromosomes slows drastically, even though a translation inhibitor has no such...