Wu Bo, Hu Guo-Ku, Feng Hong, Wu Jin-Ming, Zhang Yi-Zheng
College of Life Sciences, Sichuan Key Laboratory of Molecular Biology and Biotechnology, Sichuan University, 29 Wangjiang Road, Chengdu, 610064, Sichuan Province, PR China.
Curr Microbiol. 2007 Aug;55(2):105-13. doi: 10.1007/s00284-006-0600-x. Epub 2007 Jun 26.
Based on the genomic sequence and cDNA library screening, the cDNA sequence encoding an alpha-amylase was cloned from the filamentous white-rot fungus Phanerochaete chrysosporium and designated as pcamy1. Alignment results showed that the predicted protein has up to 43% amino acid homology to the known alpha-amylases in other organisms and is close to those from some filamentous fungi. Under nitrogen-starvation condition, the transcription of pcamy1 was accordingly upregulated or downregulated when soluble starch or glucose is sole carbon source. Addition of oxygen to nitrogen-limited media led to pcamy1 transcription and removal of glucose metabolic repression. The result indicated that the pcamy1 transcript was not only regulated by nutrients such as the carbon source but also by the cultivation environment, such as oxygen. This coordinate-regulatory model is likely common in P. chrysosporium. The expressed product of this gene in Escherichia coli could hydrolyze soluble starch, and its enzymatic activity was determined. As far as we know, this is the first report about cloning and expression study on the alpha-amylase in P. chrysosporium.
基于基因组序列和cDNA文库筛选，从丝状白腐真菌黄孢原毛平革菌（Phanerochaete chrysosporium）中克隆出编码α-淀粉酶的cDNA序列，并将其命名为pcamy1。比对结果显示，预测的蛋白质与其他生物体中已知的α-淀粉酶具有高达43%的氨基酸同源性，且与一些丝状真菌的α-淀粉酶接近。在氮饥饿条件下，当以可溶性淀粉或葡萄糖作为唯一碳源时，pcamy1的转录相应地上调或下调。向限氮培养基中添加氧气会导致pcamy1转录，并消除葡萄糖代谢阻遏。结果表明，pcamy1转录本不仅受碳源等营养物质调控，还受氧气等培养环境因素调控。这种协同调控模式在黄孢原毛平革菌中可能很常见。该基因在大肠杆菌中的表达产物能够水解可溶性淀粉，并测定了其酶活性。据我们所知，这是关于黄孢原毛平革菌中α-淀粉酶克隆与表达研究的首次报道。
