GENETIC-REGULATION OF GLYCOGEN BIOSYNTHESIS IN ESCHERICHIA-COLI - INVIVO EFFECTS OF THE CATABOLITE REPRESSION AND STRINGENT RESPONSE SYSTEMS IN GLG-GENE EXPRESSION

The synthesis of two of the Escherichia coli glycogen biosynthetic enzymes, ADPglucose pyrophosphorylase (glgC) and glycogen synthase (glgA) was activated by the addition of 5 m M cyclic AMP (cAMP) to maxicells; synthesis of glycogen branching enzyme (glgB) was unaffected. β-Galactosidase activity expressed from a gene fusion, φ(glgC-lacZ), was approximately five-fold higher in a cya+ versus an isogenic cya- strain of E. coli. Addition of cAMP restored β-galactosidase in the cya- strain. The expression of φ(glgC'-'lacZ) encoded β-galactosidase activity in a series of spoT mutants exhibited an apparent exponential relationship to intracellular guanosine 5′-diphosphate 3′-diphosphate (ppGpp) levels. These results provide evidence for the control of glycogen biosynthesis in vivo by cAMP and ppGpp at the level of gene expression, and identify a region of DNA required for the control. The φ(glgC'-'lacZ) encoded β-galactosidase activity was also elevated three-to five-fold in strain AC70R1, which contains a transacting mutation (glgQ) that affects the levels of the glycogen biosynthetic enzymes and glgC transcripts. © 1990 Springer-Verlag New York Inc.