Starmerella bombicola very efficiently produces the secondary metabolites sophorolipids (SLs). Their biosynthesis is not-growth associated and highly upregulated in the stationary phase. Despite high industrial and academic interest, the underlying regulation of SL biosynthesis remains unknown. In this paper, potential regulation of SL biosynthesis through the telomere positioning effect (TPE) was investigated, as the SL gene cluster is located adjacent to a telomere. An additional copy of this gene cluster was introduced elsewhere in the genome to investigate if this results in a decoy of regulation. Indeed, for the new strain, the onset of SL production was shifted to the exponential phase. This result was confirmed by RT-qPCR analysis. The TPE effect was further investigated by developing and applying a suitable reporter system for this non-conventional yeast, enabling non-biased comparison of gene expression between the subtelomeric CYP52M1- and the URA3 locus. This was done with a constitutive endogenous promotor (pGAPD) and one of the endogenous promotors of the SL biosynthetic gene cluster (pCYP52M1). A clear positioning effect was observed for both promotors with significantly higher GFP expression levels at the URA3 locus. No clear GFP upregulation was observed in the stationary phase for any of the new strains.

中文翻译：

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阐明轰炸星虫中槐糖脂生物合成的调控。

巨大的Starmerella bombicola非常有效地产生次生代谢产物槐糖脂（SLs）。它们的生物合成与生长无关，并且在固定相中高度上调。尽管有很高的工业和学术兴趣，但SL生物合成的潜在调控仍然未知。本文研究了通过端粒定位效应（TPE）对SL生物合成的潜在调控，因为SL基因簇位于端粒附近。在基因组的其他地方引入了该基因簇的另一个副本，以研究其是否导致调节的诱饵。确实，对于新菌株，SL的生产开始转移到了指数期。RT-qPCR分析证实了该结果。通过开发和应用适用于该非常规酵母的报告系统进一步研究TPE的作用，从而能够实现亚端粒CYP52M1-基因和URA3基因座之间基因表达的无偏比较。这是通过组成型内源性启动子（pGAPD）和SL生物合成基因簇的内源性启动子之一（pCYP52M1）完成的。对于在URA3基因座处具有明显更高的GFP表达水平的两种启动子均观察到明显的定位作用。对于任何新菌株，在固定相中均未观察到明显的GFP上调。对于在URA3基因座处具有明显更高的GFP表达水平的两种启动子均观察到明显的定位作用。对于任何新菌株，在固定相中均未观察到明显的GFP上调。对于在URA3基因座处具有明显更高的GFP表达水平的两种启动子均观察到明显的定位作用。对于任何新菌株，在固定相中均未观察到明显的GFP上调。