| Abstract: | The adenylate cyclase gene of Escherichia coli has been cloned on the plasmid vector pBR325. The hybrid plasmid pTH4 obtained has a molecular weight of 6,4 megadalton and represents pBR325 plasmid with the insertion of 2,8 megadalton in the Pst1 site. The cya mutant bacteria carrying pTH4 recover their ability to utilize mannitol, lactose and other carbohydrates as carbon sources, and lose this ability again in the case of rare spontaneous excision of the DNA insert from the Pst1 site. The phenotypical effect of pTH4 in cya mutants can be only seen in the crp+ genome. The strains carrying pTH4 are also characterized by the ability of beta-galactosidase induction under conditions of catabolite repression. Besides, the bacteria containing cya+ allele on the plasmid do not grow on glycerol, which seems to be caused by toxic concentrations of methylglyoxal formed as a result of the increased intracellular level of cyclic adenosine monophosphate. |
