Nucleic Acids Research, 1985, Vol. 13, No. 9 3147-3159
© 1985
Articles |
Diphtheria toxin promoter function in Corynebacterium diphtheriae and Escherichia coli
Groupement de Génie Génétique, Institut Pasteur 28 rue du Docteur Roux, 75724 Paris, France
Received February 25, 1985. Revised April 12, 1985. Accepted April 12, 1985.
The expression of the diphtheria tox228 gene encoding the nontoxic, serologically related CRM228 mutant diphtheria toxin has been analyzed in Coryne-bacterium diphtheriae and Escherichia coli. The diphtheria toxin pramoter has been used to direct the expression of ß-galactosidase in E.coli and the efficiency of promotion has been campared to that obtained with the lac promoter. Expression in C.diphtheriae is known to be dependent on the absence of iron, and we present for the first time direct evidence that this regulation occurs at the level of transcription. The 5' end of toxin mRNA maps at the same position in C.diphtheriae and E.coli suggesting identical sequences to be recognized by C.diphtheriae and E. coli RNA polymerase. The diphtheria toxin promoter carries at position 34 a TTGATT sequence closely related to the E.coli 35 consensus sequence and in the 14 to 8 region a set of overlapping sequences with canplete or partial homology to the E.coli 10 consensus sequence.