Regulation of carbohydrate permeases and adenylate cyclase in Escherichia coli. Studies with mutant strains in which enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system is thermolabile

Castro, L.; Feucht, B.U.; Morse, M.L.; Saier, M.H.

Journal of Biological Chemistry 251(18): 5522-5527

1976


ISSN/ISBN: 0021-9258
PMID: 184083
Accession: 006286972

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Abstract
Carbohydrate uptake and cyclic AMP synthesis were studied employing mutant strains of E. coli in which Enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system was heat-labile. Partial loss of Enzyme I activity, resulting from incubatin of cells at the nonpermissive temperature, depressed the rate and extent of methyl .alpha.-glucoside uptake. Temperature inactivation of Enzyme I also rendered cyclic AMP synthesis and the uptake of several carbohydrates (glycerol, maltose, melibiose and lactose) hypersensitive to inhibition by methyl .alpha.-glucoside. Protein synthesis is probably not required for these effects. The parental strains and revertant strains in which Eznymed I was less sensitive to temperature did not exhibit heat-enhanced regulation. Inhibition was abolished by the crr mutation. Enzyme I apparently functions as a catalytic component of the regulatory system. Simple position selection procedures are described for the isolation of bacterial mutants which are deficient for either Enzyme I or the heat-stable protein of the phosphotransferase system.