Positive Control in the L-arabinose Gene-Enzyme Complex of Escherichia coli B/r as Exhibited with Stable Merodiploids

We shall describe some recent complementation experiments with merodiploids that confirm and further amplify the proposed positive control of gene expression in the L-arabinose system in Escherichia coli B/r. These experiments were made possible by the construction of an Hfr in E. coli B/r by Dr. Herbert Boyer (J. Bacteriol. 91: 1767, 1966), and the subsequent isolation by Sheppard of an F′ ara carrying the L-arabinose genes located between threonine and leucine on the coli chromosome. With Mr. J. Power in our laboratory finding a regulatory gene in the L-rhamnose system of E. coli K12 (Bacteriol. Proc., p. 101, 1966) which is similar to that found in the Larabinose system; with the previous demonstration of positive control by gene R1 in the alkaline phosphatase system; with the likelihood that the pyruvic dehydrogenase system, as presented in this symposium by Dr. Henning, also may have a similar regulatory gene to that...