Biotica Technology Ltd, 3 Riverside Suite 5, Granta Park, Cambridge CB21 6AD, UK.
Metab Eng. 2013 Jan;15:167-73. doi: 10.1016/j.ymben.2012.11.001. Epub 2012 Nov 17.
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 250mg/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.
rapK 基因是 DHCHC 起始酸生物合成所必需的，该酸起始雷帕霉素生物合成。rapK 基因从 BIOT-3410 菌株中缺失，BIOT-3410 是经经典的菌株和工艺开发的雷帕霉素链霉菌的衍生物，能够在高达 250mg/L 的滴度下进行稳健的雷帕霉素生产。由此产生的 BIOT-4010 菌株不再能够产生雷帕霉素，但当外源提供 DHCHC 时，其产生的雷帕霉素的滴度与亲本菌株相当。该菌株使突变合成能够获得新的雷帕霉素类似物，当用 DHCHC 类似物喂养时，这些类似物不能从低滴度菌株中轻易分离出来。一些雷帕霉素类似物的突变合成主要导致缺乏后期聚酮合酶生物合成修饰的化合物。为了提高完全成熟的雷帕霉素类似物的相对产量，表达了外源异位表达那些不能有效地作用于新型化合物的晚期作用生物合成途径酶基因，得到 BIOT-4110 菌株。BIOT-4010 和 BIOT-4110 菌株代表了使用生物合成药物化学进行天然产物先导优化和生产用于临床前和早期临床试验的雷帕霉素类似物的有价值的工具。
