Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA.
Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
Nat Metab. 2023 Jul;5(7):1127-1140. doi: 10.1038/s42255-023-00830-x. Epub 2023 Jul 13.
Corynebacterium glutamicum is a promising host for production of valuable polyketides. Propionate addition, a strategy known to increase polyketide production by increasing intracellular methylmalonyl-CoA availability, causes growth inhibition in C. glutamicum. The mechanism of this inhibition was unclear before our work. Here we provide evidence that accumulation of propionyl-CoA and methylmalonyl-CoA induces growth inhibition in C. glutamicum. We then show that growth inhibition can be relieved by introducing methylmalonyl-CoA-dependent polyketide synthases. With germicidin as an example, we used adaptive laboratory evolution to leverage the fitness advantage of polyketide production in the presence of propionate to evolve improved germicidin production. Whole-genome sequencing revealed mutations in germicidin synthase, which improved germicidin titer, as well as mutations in citrate synthase, which effectively evolved the native glyoxylate pathway to a new methylcitrate pathway. Together, our results show that C. glutamicum is a capable host for polyketide production and we can take advantage of propionate growth inhibition to drive titers higher using laboratory evolution or to screen for production of polyketides.
谷氨酸棒杆菌是生产有价值的聚酮化合物的有前途的宿主。丙酸盐添加，一种通过增加细胞内甲基丙二酰辅酶 A 的可用性来增加聚酮化合物产量的策略，会导致谷氨酸棒杆菌的生长抑制。在我们的工作之前，这种抑制的机制尚不清楚。在这里，我们提供的证据表明，丙酰辅酶 A 和甲基丙二酰辅酶 A 的积累会诱导谷氨酸棒杆菌的生长抑制。然后我们表明，生长抑制可以通过引入依赖甲基丙二酰辅酶 A 的聚酮合酶来缓解。以杆菌肽为例，我们使用适应性实验室进化利用丙酸盐存在下聚酮化合物生产的适应性优势，进化出更好的杆菌肽生产。全基因组测序揭示了杆菌肽合酶的突变，提高了杆菌肽的效价，以及柠檬酸合酶的突变，有效地将天然乙醛酸途径进化为新的甲基柠檬酸途径。总之，我们的结果表明，谷氨酸棒杆菌是一种有能力生产聚酮化合物的宿主，我们可以利用丙酸盐的生长抑制作用，通过实验室进化来提高产量，或者筛选聚酮化合物的生产。
