Department of Chemistry and Nanoscience, Ewha Womans University, Seoul, Republic of Korea.
Nat Chem Biol. 2011 Oct 9;7(11):843-52. doi: 10.1038/nchembio.671.
Kanamycin is one of the most widely used antibiotics, yet its biosynthetic pathway remains unclear. Current proposals suggest that the kanamycin biosynthetic products are linearly related via single enzymatic transformations. To explore this system, we have reconstructed the entire biosynthetic pathway through the heterologous expression of combinations of putative biosynthetic genes from Streptomyces kanamyceticus in the non-aminoglycoside-producing Streptomyces venezuelae. Unexpectedly, we discovered that the biosynthetic pathway contains an early branch point, governed by the substrate promiscuity of a glycosyltransferase, that leads to the formation of two parallel pathways in which early intermediates are further modified. Glycosyltransferase exchange can alter flux through these two parallel pathways, and the addition of other biosynthetic enzymes can be used to synthesize known and new highly active antibiotics. These results complete our understanding of kanamycin biosynthesis and demonstrate the potential of pathway engineering for direct in vivo production of clinically useful antibiotics and more robust aminoglycosides.
卡那霉素是应用最广泛的抗生素之一，但它的生物合成途径仍不清楚。目前的提议表明，通过单酶转化，卡那霉素生物合成产物呈线性相关。为了探索这个系统，我们通过在非氨基糖苷产生菌委内瑞拉链丝菌中异源表达来自链霉菌的推定生物合成基因的组合，重建了整个生物合成途径。出乎意料的是，我们发现生物合成途径包含一个早期分支点，由糖基转移酶的底物多样性控制，导致形成两条平行途径，其中早期中间体进一步修饰。糖基转移酶交换可以改变这两条平行途径的通量，并且可以添加其他生物合成酶来合成已知和新的高活性抗生素。这些结果完成了我们对卡那霉素生物合成的理解，并证明了途径工程在体内直接生产临床有用抗生素和更稳健的氨基糖苷类药物的潜力。
