OBJECTIVES To reveal the potential mechanism and key determinants that contributed to the improved pectinase activity in Aspergillus niger mutant EIMU2, which was previously obtained by UV-mutagenesis from the wild-type A. niger EIM-6. RESULTS Proteomic analysis for Aspergillus niger EIMU2 by two-dimensional electrophoresis demonstrated that mutant EIMU2 harbored a multiple enzyme system for the degradation of pectin, mainly constituting by main-chain-cleaving enzymes polygalacturonase, pectate lyase, pectinesterase, and some accessory enzymes rhamnogalacturonan lyase and arabinofuranosidase. Further quantitatively differential proteomic analysis revealed that the quantities of four proteins, pectinesterase, rhamnogalacturonan lyase A, DNA-directed RNA polymerase A, and a hypothetical protein in strain EIMU2 were much higher than those in EIM-6. PCR amplification, sequencing and alignment analysis of genes for the two main members of pectin-degrading enzymes, pectate lyase and polygalacturonase showed that their sequences were completely consistent in A. niger EIM-6 and mutant EIMU2. CONCLUSIONS The result demonstrated that the improved pectinase activity by UV-mutagenesis in A. niger EIMU2 was probably contributed to the up-regulated expression of rhamnogalacturonan lyase, or pectinesterase, which resulted in the optimization of synergy amongst different components of pectin-degrading enzymes.

中文翻译：

---

差异蛋白质组学揭示了紫外线诱变黑曲霉菌株果胶酶活性提高的主要决定因素

目的 揭示导致黑曲霉突变体 EIMU2 果胶酶活性提高的潜在机制和关键决定因素，该突变体 EIMU2 先前是通过紫外线诱变从野生型黑曲霉 EIM-6 获得的。结果黑曲霉EIMU2二维电泳蛋白质组学分析表明，突变体EIMU2具有多酶系统降解果胶，主要由主链切割酶聚半乳糖醛酸酶、果胶酸裂解酶、果胶酯酶和一些辅助酶鼠李糖半乳糖醛酸裂解酶和阿拉伯呋喃糖苷酶。进一步的定量差异蛋白质组学分析表明，EIMU2 菌株中四种蛋白质、果胶酯酶、鼠李糖半乳糖醛酸裂解酶 A、DNA 指导的 RNA 聚合酶 A 和一种假设蛋白质的数量远高于 EIM-6。果胶降解酶的两个主要成员果胶裂解酶和多聚半乳糖醛酸酶的基因PCR扩增、测序和比对分析表明，它们在黑曲霉EIM-6和突变体EIMU2中的序列完全一致。结论 结果表明，通过紫外线诱变在黑曲霉 EIMU2 中提高的果胶酶活性可能是由于鼠李糖半乳糖醛酸裂解酶或果胶酯酶的表达上调，从而优化了果胶降解酶不同成分之间的协同作用。