Molecular cloning and expression of gene fragments from corynebacteriophage beta encoding enzymatically active peptides of diphtheria toxin

Abstract

Two restriction fragments from corynebacteriophage .beta.vir tox+ that encode peptides similars to diphtheria toxin fragment A and the chain termination fragment, CRM45, were cloned into Escherichia coli in plasmid pBR322. Clones containing the recombinant plasmids produced gene products that catalyzed the ADP ribosylation of elongation factor 2 and reacted with diphtheria toxin antiserum. Toxin-related peptides were found primarily in the periplasmic compartment and were degraded to nonimmunoreactive forms within 1-2 h of synthesis. The expression of both gene fragments appeared to originate from the diphtheria toxin promoter.