Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093, USA.
Appl Environ Microbiol. 2011 Oct;77(20):7261-70. doi: 10.1128/AEM.05943-11. Epub 2011 Aug 26.
The marine actinomycete genus Salinispora is composed of three closely related species. These bacteria are a rich source of secondary metabolites, which are produced in species-specific patterns. This study examines the distribution and phylogenetic relationships of genes involved in the biosynthesis of secondary metabolites in the salinosporamide and staurosporine classes, which have been reported for S. tropica and S. arenicola, respectively. The focus is on "Salinispora pacifica," the most recently discovered and phylogenetically diverse member of the genus. Of 61 S. pacifica strains examined, 15 tested positive for a ketosynthase (KS) domain linked to the biosynthesis of salinosporamide K, a new compound in the salinosporamide series. Compound production was confirmed in two strains, and the domain phylogeny supports vertical inheritance from a common ancestor shared with S. tropica, which produces related compounds in the salinosporamide series. There was no evidence for interspecies recombination among salA KS sequences, providing further support for the geographic isolation of these two salinosporamide-producing lineages. In addition, staurosporine production is reported for the first time for S. pacifica, with 24 of 61 strains testing positive for staD, a key gene involved in the biosynthesis of this compound. High levels of recombination were observed between staD alleles in S. pacifica and the cooccurring yet more distantly related S. arenicola, which produces a similar series of staurosporines. The distributions and phylogenies of the biosynthetic genes examined provide insight into the complex processes driving the evolution of secondary metabolism among closely related bacterial species.
海洋放线菌属 Salinispora 由三个密切相关的物种组成。这些细菌是次生代谢产物的丰富来源，其产物具有物种特异性。本研究考察了参与 Salinosporamide 和 Staurosporine 类化合物生物合成的基因在 Salinispora tropica 和 S. arenicola 中分别报道的分布和系统发育关系。研究重点是“Salinispora pacifica”，这是该属中最新发现的、系统发育多样性最高的成员。在 61 株 S. pacifica 菌株中，有 15 株检测到与 Salinosporamide K 生物合成有关的酮合酶（KS）结构域呈阳性，这是 Salinosporamide 系列中的一种新化合物。在两种菌株中确认了化合物的产生，并且该结构域的系统发育支持与产生相关化合物的 S. tropica 有共同祖先的垂直遗传。在 SalA KS 序列中没有种间重组的证据，这进一步支持了这两个 Salinosporamide 产生谱系的地理隔离。此外，首次报道了 S. pacifica 产生 Staurosporine，在 61 株菌株中有 24 株检测到 staD 呈阳性，这是该化合物生物合成的关键基因。在 S. pacifica 和同时存在的但亲缘关系更远的 S. arenicola 之间观察到 staD 等位基因之间存在高水平的重组，后者产生了类似的 Staurosporine 系列。所研究的生物合成基因的分布和系统发育为深入了解次生代谢物在密切相关的细菌物种中的进化复杂过程提供了线索。
