The structural gene of the carboxypeptidase T (cpt) was successfully expressed in cell wall-less L-form cells of Proteus mirabilis. The DNA sequence encoding the PhoA leader peptide was fused with a truncated cpt gene encoding the mature enzyme. The modified gene in a pUC-based kanamycin resistance vector under the control of the lac promoter was transformed into L-form cells of P. mirabilis. They were able to produce the recombinant CpT both as a secretory and as a cell-bound insoluble form. The co-secretory processing of the PhoA leader peptide was quite efficient. The yield of the secreted CpT was not less than 20 mg l-1 and should be improvable.
Bushueva, A. M., Shevelev, A. B., Gumpert, J., Chestukhina, G. G., Serkina, A. V., Hoischen, C., … Stepanov, V. M. (1998). Expression of the carboxypeptidase T gene from thermoactinomyces vulgaris in stable protoplast type L-forms of Proteus mirabilis. FEMS Microbiology Letters, 159(2), 145–150. https://doi.org/10.1016/S0378-1097(97)00495-3