Evidence for an iterative module in chain elongation on the azalomycin polyketide synthase.
Evidence for an iterative module in chain elongation on the azalomycin polyketide synthase.
复制标题
阿扎霉素聚酮合酶链延长迭代模块的证据
DOI：
10.3762/bjoc.12.206
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发表时间：
2016
影响因子：
2.7
通讯作者：
Leadlay PF
中科院分区：
文献类型：
--
作者：
Hong H;Sun Y;Zhou Y;Stephens E;Samborskyy M;Leadlay PF
生产细菌聚酮化合物天然产物的装配线酶遵循模块化范例，其中每轮链延伸由不同的酶组或模块催化。从机械论和进化论的角度来看，偏离这种范式的例子，其中一个模块催化多个扩展或没有。我们提出的证据表明，在生物合成的36元大环氨基多元醇内酯（marginolactones）azalomycin和kanchanamycin，分别从链霉菌马来西亚DSM 4137和链霉菌olivaceus Tü 4018分离，第一个扩展模块催化的第一和第二个循环的聚酮化合物链的延伸。为了确认azl基因簇的完整性，将其完整克隆在细菌人工染色体上，并移植到异源宿主菌株变铅青链霉菌中，该菌株不具有用于产生marginolactone的基因。当提供4-胍基丁酰胺时，阿扎霉素起始单元的特定前体，重组S。青丹菌素产生阿扎霉素，表明测序簇中的聚酮合酶基因足以完成全长聚酮链的形成。这为阿扎霉素和卡那霉素生物合成途径中的模块迭代提供了强有力的支持。相比之下，对阿布拉威链霉菌中用于聚酮β-内酯ebelactone生物合成的基因簇的重新测序表明，与最近公布的提议相反，ebelactone聚酮合酶忠实地遵循共线性模块化范例。
The assembly-line synthases that produce bacterial polyketide natural products follow a modular paradigm in which each round of chain extension is catalysed by a different set or module of enzymes. Examples of deviation from this paradigm, in which a module catalyses either multiple extensions or none are of interest from both a mechanistic and an evolutionary viewpoint. We present evidence that in the biosynthesis of the 36-membered macrocyclic aminopolyol lactones (marginolactones) azalomycin and kanchanamycin, isolated respectively from Streptomyces malaysiensis DSM4137 and Streptomyces olivaceus Tü4018, the first extension module catalyses both the first and second cycles of polyketide chain extension. To confirm the integrity of the azl gene cluster, it was cloned intact on a bacterial artificial chromosome and transplanted into the heterologous host strain Streptomyces lividans, which does not possess the genes for marginolactone production. When furnished with 4-guanidinobutyramide, a specific precursor of the azalomycin starter unit, the recombinant S. lividans produced azalomycin, showing that the polyketide synthase genes in the sequenced cluster are sufficient to accomplish formation of the full-length polyketide chain. This provides strong support for module iteration in the azalomycin and kanchanamycin biosynthetic pathways. In contrast, re-sequencing of the gene cluster for biosynthesis of the polyketide β-lactone ebelactone in Streptomyces aburaviensis has shown that, contrary to a recently-published proposal, the ebelactone polyketide synthase faithfully follows the colinear modular paradigm.