| abstract |
The invention discloses the use of domain II of Pseudomonas exotoxin genes in E. coli, desirably, under the control of a T7 promoter. Without a signal sequence, Pseudomonas exotoxin accumulates within the cell, but it is secreted into the periplasm when part or all of domain I is removed. PE appears in the periplasm and medium when domains I and part of II are removed. Domain II alone is secreted into the periplasm, whereas domain III alone remains within the cell. Addition of an OmpA signal sequence results in the secretion of mature PE into the periplasm and secretion of domain II-III into the medium. A protein composed of a transforming growth factor alpha fused to the amino end of domain II-III is secreted into the periplasm without a signal sequence and into the medium with a signal sequence. A protein composed of II or II-III fused to the amino end of alkaline phosphatase is secreted into the periplasm and the medium with or without a signal sequence. |