Effect of Dibutyryladenosine 3′:5′-Cylic Monophosphate on Growth and Differentiation in Caulobacter crescentus
Abstract
Caulobacter crescentus goes through a series of morphological changes during its life cycle, including the coincident expression of synthesis of flagella, pili, and receptor sites for DNA bacteriophage. Upon transfer of a mixed population of cells to medium containing lactose as the sole carbon source, these changes were blocked for about 20 hr until β-galactosidase activity became apparent. The addition of dibutyryl cyclic AMP to the blocked cultures brought about the resumption of cell differentiation, growth, and the appearance of β-galactosidase activity within 1 hr. Unlike Escherichia coli, the intracellular and extracellular concentrations of cyclic AMP in C. crescentus did not vary under several growth conditions, including catabolite repression. It would appear, therefore, that although there is an effect of cyclic AMP on the induction of β-galactosidase and differentiation in C. crescentus, regulation of these processes occurs without consistent changes in the cellular level of this nucleotide.
