| Abstract: | p-Fluorophenylalanine (FPA) causes a 100-fold increase in alkaline phosphatase in Escherichia coli B, strain PR1 at 30 C in minimal medium that contains excess inorganic phosphate (1.92 x 10(-3)m). Little increase in alkaline phosphatase synthesis occurs under these conditions at 22 C. [This strain is known to have a mutation in a regulator gene (R(2)) that, in the absence of FPA, permits derepression of alkaline phosphatase synthesis at 37 C, but not at 30 C or below.] In contrast, E. coli B3 (the strain from which E. coli B strain PR1 was derived) is not derepressed at 30 C by FPA. (14)C-FPA is incorporated into bacterial proteins. Temperature-shift experiments (30 Cright harpoon over left harpoon22 C) in the presence of FPA are consistent with the following mechanism. FPA is incorporated into the genetically altered R(2) protein at 30 and 22 C. This further alteration due to the incorporation of analogue makes the R(2) protein inactive at 30 C, but active at 22 C. |
