An Aspergillus niger strain has been constructed in which the pH-dependent regulatory gene, pacC, was disrupted. The pacC gene of A. niger, like that of A. nidulans, is involved in the regulation of acid phosphatase expression. Disruptants were identified by a reduction in acid phosphatase staining of colonies. Southern analysis demonstrated integration of the disruption plasmid at the pacC locus and Northern analysis showed that the disruption strain produced a truncated pacC mRNA of 2.2 kb (as compared to 2.8 kb in the wild type). The strain carrying the pacC disruption was used to assign the pacC gene to linkage group IV; this was confirmed by CHEF electrophoresis and Southern analysis. This strain further allowed us to determine which extracellular enzyme and transport systems are under the control of pacC in A. niger. Expression of the A. niger pacC wild-type gene and the truncated pacC gene showed that, in contrast to the auto-regulated wild-type expression, which was elevated only at alkaline pH, the truncated pacC gene was deregulated, as high-level expression occurred regardless of the pH of the culture medium. Analysis of the phosphatase spectrum by isoelectric focussing and enzyme activity staining both in the wild-type and the pacC disruptant showed that at least three acid phosphatases are regulated by the pacC. For the single alkaline phosphatase no pH regulation was observed.

译文

已经构建了黑曲霉菌株,其中pH依赖性调节基因pacC被破坏。与A.Niddulans一样,黑曲霉的pacC基因参与酸性磷酸酶表达的调节。通过减少菌落的酸性磷酸酶染色来鉴定破坏物。Southern分析证明了破坏质粒在pacC基因座上的整合,Northern分析表明,破坏菌株产生了2.2 kb的截短的pacC mRNA (与野生型中的2.8 kb相比)。携带pacC破坏的菌株用于将pacC基因分配给IV连锁组; 这已通过CHEF电泳和Southern分析得到证实。该菌株进一步使我们能够确定黑曲霉中哪些胞外酶和转运系统处于pacC的控制之下。A. niger pacC野生型基因和截短的pacC基因的表达表明,与仅在碱性pH下升高的自动调节野生型表达相反,截短的pacC基因被解除管制,无论培养基的ph值如何,都会发生高水平的表达。通过等电聚焦和酶活性染色对野生型和pacC破坏物中的磷酸酶谱进行分析表明,至少三种酸性磷酸酶受pacC调节。对于单一碱性磷酸酶,未观察到pH调节。

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