Starcevic Antonio, Akthar Shamima, Dunlap Walter C, Shick J Malcolm, Hranueli Daslav, Cullum John, Long Paul F
Section for Bioinformatics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia.
Proc Natl Acad Sci U S A. 2008 Feb 19;105(7):2533-7. doi: 10.1073/pnas.0707388105. Epub 2008 Feb 11.
The shikimic acid pathway is responsible for the biosynthesis of many aromatic compounds by a broad range of organisms, including bacteria, fungi, plants, and some protozoans. Animals are considered to lack this pathway, as evinced by their dietary requirement for shikimate-derived aromatic amino acids. We challenge the universality of this traditional view in this report of genes encoding enzymes for the shikimate pathway in an animal, the starlet sea anemone Nematostella vectensis. Molecular evidence establishes horizontal transfer of ancestral genes of the shikimic acid pathway into the N. vectensis genome from both bacterial and eukaryotic (dinoflagellate) donors. Bioinformatic analysis also reveals four genes that are closely related to those of Tenacibaculum sp. MED152, raising speculation for the existence of a previously unsuspected bacterial symbiont. Indeed, the genome of the holobiont (i.e., the entity consisting of the host and its symbionts) comprises a high content of Tenacibaculum-like gene orthologs, including a 16S rRNA sequence that establishes the phylogenetic position of this associate to be within the family Flavobacteriaceae. These results provide a complementary view for the biogenesis of shikimate-related metabolites in marine Cnidaria as a "shared metabolic adaptation" between the partners.
莽草酸途径负责多种生物合成多种芳香族化合物，这些生物包括细菌、真菌、植物和一些原生动物。动物被认为缺乏这条途径，这从它们对莽草酸衍生的芳香族氨基酸的饮食需求中可以看出。在本报告中，我们对这一传统观点的普遍性提出了质疑，该报告涉及一种动物——星状海葵（Nematostella vectensis）中编码莽草酸途径酶的基因。分子证据证实了莽草酸途径的祖先基因从细菌和真核生物（甲藻）供体水平转移到星状海葵的基因组中。生物信息学分析还揭示了四个与海杆菌属（Tenacibaculum sp.）MED152的基因密切相关的基因，这引发了对一种此前未被怀疑的细菌共生体存在的推测。确实，全生物（即由宿主及其共生体组成的实体）的基因组包含高含量的类海杆菌属基因直系同源物，包括一个16S rRNA序列，该序列确定了这种共生体在黄杆菌科中的系统发育位置。这些结果为海洋刺胞动物中莽草酸相关代谢物的生物合成提供了一种补充观点，即作为伙伴之间的“共享代谢适应”。
