Activation of a plasmid-situated type III PKS gene cluster by deletion of a wbl gene in deepsea-derived Streptomyces somaliensis SCSIO ZH66.
Activation of a plasmid-situated type III PKS gene cluster by deletion of a wbl gene in deepsea-derived Streptomyces somaliensis SCSIO ZH66.
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DOI：
10.1186/s12934-016-0515-6
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发表时间：
2016-06-27
影响因子：
6.4
通讯作者：
Li W
中科院分区：
文献类型：
--
作者：
Huang H;Hou L;Li H;Qiu Y;Ju J;Li W
放线菌基因组测序已经揭示了大量隐蔽的次生代谢产物生物合成基因簇。然而，它们的不可用或有限的表达严重阻碍了生物活性化合物的发现。whiB-like（wbl）调控基因在形态分化和次生代谢中起重要作用，因此，以wblAso基因为靶基因，对深海源索马里链霉菌SCSIO ZH 66的隐蔽基因簇进行了激活。wblAso来自深海S.通过对somaliensis SCSIO ZH 66进行失活，使ΔwblAso突变体的次生代谢产物产生显著变化，从中分离得到α-吡喃酮化合物violapyrone B（VLP B）。随后，VLP生物合成基因簇被鉴定和表征，其由III型聚酮合酶（PKS）基因vioA和调控基因vioB组成;令人高兴的是，vioB的失活导致另外四个VLP类似物的分离，其中一个是新的，两个表现出比VLP B更高的抗MRSA（耐甲氧西林金黄色葡萄球菌，MRSA）活性。此外，转录水平分析表明，whi基因（whiD、whiG、whiH和whiI）和wbl基因（wblC、wblE、wblH、wblI和wblK）的表达水平受到不同程度的抑制，表明wblAso对S.索马里种SCSIO ZH 66. wblA同源基因可能是海洋链霉菌隐性基因簇激活的有效靶基因，但不同链霉菌的调控机制可能不同。此外，vio基因簇的可用性丰富了III型PKS的多样性，为通过生物合成工程扩大聚酮化合物的化学空间提供了新的机会。本文的在线版本（doi：10.1186/s12934-016-0515-6）包含补充材料，可供授权用户使用。
Actinomycete genome sequencing has disclosed a large number of cryptic secondary metabolite biosynthetic gene clusters. However, their unavailable or limited expression severely hampered the discovery of bioactive compounds. The whiB-like (wbl) regulatory genes play important roles in morphological differentiation as well as secondary metabolism; and hence the wblAso gene was probed and set as the target to activate cryptic gene clusters in deepsea-derived Streptomyces somaliensis SCSIO ZH66. wblAso from deepsea-derived S. somaliensis SCSIO ZH66 was inactivated, leading to significant changes of secondary metabolites production in the ΔwblAso mutant, from which α-pyrone compound violapyrone B (VLP B) was isolated. Subsequently, the VLP biosynthetic gene cluster was identified and characterized, which consists of a type III polyketide synthase (PKS) gene vioA and a regulatory gene vioB; delightedly, inactivation of vioB led to isolation of another four VLPs analogues, among which one was new and two exhibited improved anti-MRSA (methicillin-resistant Staphylococcus aureus, MRSA) activity than VLP B. Moreover, transcriptional analysis revealed that the expression levels of whi genes (whiD, whiG, whiH and whiI) and wbl genes (wblC, wblE, wblH, wblI and wblK) were repressed by different degrees, suggesting an intertwined regulation mechanism of wblAso in morphological differentiation and secondary metabolism of S. somaliensis SCSIO ZH66. wblA orthologues would be effective targets for activation of cryptic gene clusters in marine-derived Streptomyces strains, notwithstanding the regulation mechanisms might be varied in different strains. Moreover, the availability of the vio gene cluster has enriched the diversity of type III PKSs, providing new opportunities to expand the chemical space of polyketides through biosynthetic engineering. The online version of this article (doi:10.1186/s12934-016-0515-6) contains supplementary material, which is available to authorized users.