A novel biosynthetic pathway for the unique volatile 'sodorifen' of Serratia odorifera 4Rx13

挥发物是物种间和物种内公认的交流和识别信号。直到最近才证明，除了其他生物体外，细菌也会释放出大量的挥发物。特别丰富的是气味沙雷氏菌4Rx13的混合物（多达100种挥发物）。优势化合物（C16H32, 1,2,4,5,6,7,8-七甲基-3-亚甲基双环[3.2.1]辛-6-烯，命名为sodorifen）的结构是科学上独特而新颖的。多甲基化结构是非常罕见的，生物合成途径是完全未知的，目前还无法预测。以下策略将用于阐明这种新的天然化合物的生物合成途径：1)饲养实验表明met， thr, ala, his, lyys，或琥珀酸盐和富马酸盐是生物合成sodorifen的有利底物。随后，13氨基酸和13c -琥珀酸，NMR将用于预测sodorifen的组成和潜在的反应。ii)发射和不发射硫多利芬的沙雷菌的蛋白质组应该允许检测硫多利芬生物合成酶。iii)对S. odorifera 4Rx13的基因组进行了完整测序，以支持推测的生物合成基因的鉴定。新分离的基因将用于a)通过敲除突变体对其进行功能表征，b)在宏基因组文库中寻找生物合成途径的起源。最终，将启动有关sodorifen的生物学/生态学相关性的研究。

Volatiles are well-established inter and intra species communication and recognition signals. Only recently it was demonstrated that beside other organisms also bacteria emit a wealth of volatiles. Particularly rich is the blend of Serratia odorifera 4Rx13 (up to 100 volatiles). The structure of the dominant compound (C16H32, 1,2,4,5,6,7,8-heptamethyl-3-methylenebicyclo[3.2.1]oct-6-ene, named sodorifen) is unique and novel to science. The polymethylated structure is extremely unusual and the biosynthetic pathway is completely unknown and presently not predictable. The following strategies will be performed to elucidate the biosynthetic pathway of this new natural compound: i) Feeding experiments indicated met, thr, ala, his, lys, or succinate and fumarate as favored substrates for the biosynthesis of sodorifen. Subsequently 13Camino acids and 13C-succinate, and NMR will be performed to predict the composition of sodorifen and the underlying reactions. ii) Proteomes of sodorifen emitting and non-emitting Serratia species should allow the detection of sodorifen biosynthesis enzymes. iii) The genome of S. odorifera 4Rx13 was completely sequenced to support the identification of putative biosynthesis genes. Newly isolated genes will be used a) to functionally characterize them via knockout mutants and b) to search for the origin of the biosynthetic pathway in metagenomic libraries. Ultimately research concerning the biological/ecological relevance of sodorifen will be initiated.