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 str ain of Escherichia coli deficient in dipZ, a gene coding for a protein involved in cytochrome c biogenesis, and the isogenic wild-type strai n. The yield of soluble and active human placental alkaline phosphatas e was significantly reduced in the mutant but could be fully recovered by expression of dipZ subcloned in a vector with low copy number. Ove rexpression of E. coil alkaline phosphatase was unaffected in the muta nt with or without dipZ co-expression.