THE BGLG GROUP OF ANTITERMINATORS - A GROWING FAMILY OF BACTERIAL REGULATORS

The product of the bglG gene of Escherichia coli was among the first b acterial antiterminators to be identified and characterized. Since the elucidation ten years ago of its role in the regulation of the bgl op eron of E. coli, a large number of homologues have been discovered in both Gram-positive and Gram-negative bacteria. Often the homologues of BglG in other organisms are also involved in regulating beta-glucosid e utilization. Surprisingly, in many cases, they mediate antiterminati on to regulate a variety of other catabolic functions. Because of the high degree of conservation of the cis-acting regulatory elements, ant iterminators from one organism can function in another. Generally the antiterminator protein itself is negatively regulated by phosphorylati on by a component of the phosphotransferase system. This family of pro teins thus represents a highly evolved regulatory system that is conse rved across evolutionarily distant genuses.