EXTRACELLULAR EXPRESSION OF NATIVE HUMAN ANTILYSOZYME FRAGMENTS IN STAPHYLOCOCCUS-CARNOSUS

Xylose-inducible vectors have been constructed for extracellular produ ction of antibody fragments in Staphylococcus carnosus. The pre-pro se quence of S. hyicus lipase was taken as secretional signal sequence, a nd the S. xylosus Xyl repressor was used to confer xylose inducibility of transcription. Cleavage sites for the IgA protease were engineered between the pre-pro sequence and the antibody fragments to permit rem oval of the pro sequence. Extracellular expression of the light chain and the Fd fragment of a chimeric Fab fragment containing the variable regions of the anti-lysozyme antibody D1.3 was achieved with these ve ctors. The pro sequence could be removed from the expression product b y IgA protease treatment. When the light chain and the Fd fragment wer e co-secreted as a protein fusion they accumulated in a structure capa ble of heterodimerization after IgA cleavage. This fusion contains the pre-pro sequence followed by the light chain, a second IgA site and t he Fd fragment.