Abstract: A recombinant DNA construct, useful for obtaining excretion from E. coli of a heterologous protein, comprises a coding region in which DNA coding for the heterologous protein in coupled in reading frame with DNA coding for the OmpA signal peptide, to enable secretion of the protein into the periplasm; and a control region linked operably with the coding region to enable expression thereof in an E. coli host, wherein the control region comprises the tac promoter, the lac operator and a consensus ribosome binding site. With this construct, the excretion of heterologous proteins from E. coli can be achieved, consistently and for a wide variety of such proteins, without assistance from carrier proteins or membrane-lytic agent and by using "healthy" hosts rather than mutant strains having defective outer membranes.

Abstract: A recombinant DNA construct, useful for obtaining excretion from E. coli of a heterologous protein, comprises a coding region in which DNA coding for the heterologous protein in coupled in reading frame with DNA coding for the OmpA signal peptide, to enable secretion of the protein into the periplasm; and a control region linked operably with the coding region to enable expression thereof in an E. coli host, wherein the control region comprises the tac promoter, the lac operator and a consensus ribosome binding site. With this construct, the excretion of heterologous proteins from E. coli can be achieved, consistently and for a wide variety of such proteins, without assistance from carrier proteins or membrane-lytic agent and by using "healthy" hosts rather than mutant strains having defective outer membranes.