Salmonella

Salmonella is a genus of bacteria whose members include organisms associated with intestinal and systemic infections. Species and serovar distinctions matter: the genus name does not specify one host range or one clinical course. Its members also provide experimentally tractable examples of gene regulation.

In the FourU RNA thermometer, base pairing in a messenger RNA controls access to a ribosome-binding region. Structure-probing and translation experiments showed how temperature-dependent opening can alter expression of a heat-shock protein. ^[ref] The example separates a change in RNA structure from a change in DNA sequence: environmental conditions can alter the output of the same encoded regulatory element.