Boronated tartrolon antibiotic produced by symbiotic cellulose-degrading bacteria in shipworm gills
Boronated tartrolon antibiotic produced by symbiotic cellulose-degrading bacteria in shipworm gills
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DOI：
10.1073/pnas.1213892110
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发表时间：
2013-01-22
影响因子：
11.1
通讯作者：
Haygood, Margo G.
中科院分区：
文献类型：
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作者：
Elshahawi, Sherif I.;Trindade-Silva, Amaro E.;Haygood, Margo G.
船虫是一种海洋蛀木双壳类软体动物（船虫科），其鳃内有一群密切相关的γ变形杆菌作为细胞内共生体。这些共生体已被提出协助船虫宿主消化纤维素，并已被证明在固氮中发挥作用。对第一个培养的船虫共生体Teredinibacter turnerae菌株的基因组进行了测序，揭示了其作为多酮和非核糖体肽的丰富来源的潜力。采用生物测定法分离鉴定了两种大二萜多酮，均属龙蒿属。两种化合物均具有抗菌作用，其中主要化合物对其他船虫共生菌株和多种致病菌均有抑制作用。鉴定了合成这些化合物的基因簇，并对酮合酶结构域进行了系统发育分析。反转录PCR、液相色谱法、高分辨率质谱法和串联质谱法等检测手段揭示了这些基因的转录和化合物在船虫体内的存在，表明该基因簇在体内表达，这些化合物可能对船虫宿主具有特定的功能。本研究报道了从一种船虫共生体中提取的海鲢多酮类化合物，并揭示了该类化合物中一个成员的生物合成基因簇，这可能揭示了这些生物活性代谢物的生物合成机制。
Shipworms are marine wood-boring bivalve mollusks (family Teredinidae) that harbor a community of closely related Gammaproteobacteria as intracellular endosymbionts in their gills. These symbionts have been proposed to assist the shipworm host in cellulose digestion and have been shown to play a role in nitrogen fixation. The genome of one strain of Teredinibacter turnerae, the first shipworm symbiont to be cultivated, was sequenced, revealing potential as a rich source of polyketides and nonribosomal peptides. Bioassay-guided fractionation led to the isolation and identification of two macrodioloide polyketides belonging to the tartrolon class. Both compounds were found to possess antibacterial properties, and the major compound was found to inhibit other shipworm symbiont strains and various pathogenic bacteria. The gene cluster responsible for the synthesis of these compounds was identified and characterized, and the ketosynthase domains were analyzed phylogenetically. Reverse-transcription PCR in addition to liquid chromatography and high-resolution mass spectrometry and tandem mass spectrometry revealed the transcription of these genes and the presence of the compounds in the shipworm, suggesting that the gene cluster is expressed in vivo and that the compounds may fulfill a specific function for the shipworm host. This study reports tartrolon polyketides from a shipworm symbiont and unveils the biosynthetic gene cluster of a member of this class of compounds, which might reveal the mechanism by which these bioactive metabolites are biosynthesized.