Author/Authors :
Kendrew، نويسنده , , Steven G. and Petkovic، نويسنده , , Hrvoje and Gaisser، نويسنده , , Sabine and Ready، نويسنده , , Sarah J. and Gregory، نويسنده , , Matthew A. and Coates، نويسنده , , Nigel J. and Nur-e-Alam، نويسنده , , Mohammad and Warneck، نويسنده , , Tony and Suthar، نويسنده , , Dipen and Foster، نويسنده , , Teresa A. and McDonald، نويسنده , , Leonard and Schlingman، نويسنده , , Gerhard and Koehn، نويسنده , , Frank E. and Skotnicki، نويسنده , , Jerauld S. and Carter، نويسنده , , Guy T. and Moss، نويسنده , , Steven J. and Zhang، نويسنده , , Ming-Qiang and Martin، نويسنده , , Christine J. and Sheridan، نويسنده , , Rose M. and Wilkinson، نويسنده , , Barrie، نويسنده ,
Abstract :
The rapK gene required for biosynthesis of the DHCHC starter acid that initiates rapamycin biosynthesis was deleted from strain BIOT-3410, a derivative of Streptomyces rapamycinicus which had been subjected to classical strain and process development and capable of robust rapamycin production at titres up to 250 mg/L. The resulting strain BIOT-4010 could no longer produce rapamycin, but when supplied exogenously with DHCHC produced rapamycin at titres equivalent to its parent strain. This strain enabled mutasynthetic access to new rapalogs that could not readily be isolated from lower titre strains when fed DHCHC analogs. Mutasynthesis of some rapalogs resulted predominantly in compounds lacking late post polyketide synthase biosynthetic modifications. To enhance the relative production of fully elaborated rapalogs, genes encoding late-acting biosynthetic pathway enzymes which failed to act efficiently on the novel compounds were expressed ectopically to give strain BIOT-4110. Strains BIOT-4010 and BIOT-4110 represent valuable tools for natural product lead optimization using biosynthetic medicinal chemistry and for the production of rapalogs for pre-clinical and early stage clinical trials.
