Escherichia coli Skp chaperone coexpression improves solubility and phage display of single-chain antibody fragments

Expression of single-chain antibody fragments (scAb) in the periplasm of Es cherichia colt often results in low soluble product yield and cell lysis. W e have increased scAb solubility and prevented cell culture lysis by coexpr essing the E. coli Skp chaperone gene. A mutant Skp cistron was linked to a bacteriophage T7 gene 10 translational initiation region and placed either downstream of a scAb gene within an isopropyl beta-D-thiogalactopyranoside -inducible expression cassette or on a separate colE1-compatible arabinose- inducible vector. Increases in scAb solubility reflected the amount of coex pressed Skp. A bacteriophage display vector that was also engineered to coe xpress Skp permitted display of a virtually undisplayable scab and should p rove useful in expanding library sizes. (C) 1999 Academic Press.