MUTATION IN DIPZ LEADS TO REDUCED PRODUCTION OF ACTIVE HUMAN PLACENTAL ALKALINE-PHOSPHATASE IN ESCHERICHIA-COLI

We have tested the expression of alkaline phosphatases in a mutant strain of Escherichia coli deficient in dipZ, a gene coding for a protein involved in cytochrome c biogenesis, and the isogenic wild-type strain. The yield of soluble and active human placental alkaline phosphatase was significantly reduced in the mutant but could be fully recovered by expression of dipZ subcloned in a vector with low copy number. Overexpression of E. coli alkaline phosphatase was unaffected in the mutant with or without dipZ co-expression.