Widespread occurrence and genomic context of unusually small polyketide synthase genes in microbial consortia associated with marine sponges
Widespread occurrence and genomic context of unusually small polyketide synthase genes in microbial consortia associated with marine sponges
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DOI：
10.1128/aem.02260-06
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发表时间：
2007-04-01
影响因子：
4.4
通讯作者：
Piel, Joern
中科院分区：
文献类型：
--
作者：
Fieseler, Lars;Hentschel, Ute;Piel, Joern
许多海洋海绵在其组织中含有大量尚未培养的细菌。越来越多的证据表明，这些共生体在合成保护性代谢物中发挥重要作用，其中许多具有很大的药理学意义。在这项研究中，基因的生物合成的聚酮化合物，最重要的一类生物活性的天然产物，系统地调查了20种来自不同的海洋demosponge。出乎意料的是，海绵宏基因组由一个普遍存在的，进化上不同的，高度海绵特异性的聚酮酶（PKS）。在从Theonella swinhoei和Aplysina aerophoba的宏基因组中分离的三个相应的DNA区域上发现了类似于动物脂肪酸基因的开放阅读框架。它们的结构表明甲基支链脂肪酸是代谢产物。根据管家基因的系统发育分析，至少有一个PKS属于异常球菌-栖热菌门的细菌。这些结果为海绵共生体的化学性质提供了新的见解，并允许推断海绵宏基因组中存在的不同功能PKS类型的详细遗传。基于这些定性和定量的数据，我们提出了一个显着简化的策略，有针对性地分离生物医学相关的PKS基因复杂的海绵共生体协会。
Numerous marine sponges harbor enormous amounts of as-yet-uncultivated bacteria in their tissues. There is increasing evidence that these symbionts play an important role in the synthesis of protective metabolites, many of which are of great pharmacological interest. In this study, genes for the biosynthesis of polyketides, one of the most important classes of bioactive natural products, were systematically investigated in 20 demosponge species from different oceans. Unexpectedly, the sponge metagenomes were dominated by a ubiquitously present, evolutionarily distinct, and highly sponge-specific group of polyketide synthases (PKSs). Open reading frames resembling animal fatty acid genes were found on three corresponding DNA regions isolated from the metagenomes of Theonella swinhoei and Aplysina aerophoba. Their architecture suggests that methyl-branched fatty acids are the metabolic product. According to a phylogenetic analysis of housekeeping genes, at least one of the PKSs belongs to a bacterium of the Deinococcus-Thermus phylum. The results provide new insights into the chemistry of sponge symbionts and allow inference of a detailed phylogeny of the diverse functional PKS types present in sponge metagenomes. Based on these qualitative and quantitative data, we propose a significantly simplified strategy for the targeted isolation of biornedically relevant PKS genes from complex sponge-symbiont associations.