Regulatory mechanism for selective expression of silent paralogous genes in filamentous fungi

在黑曲霉基因组中存在两个与麦芽糖同化有关的旁系同源基因簇。这些簇都由三个基因组成，每个基因分别编码转运蛋白、α-葡萄糖苷酶和转录因子，其中一个是功能性的，但另一个似乎是转录沉默的。然而，有趣的是，当功能基因被破坏时，这些沉默基因被诱导转录。通过互补实验证明该基因编码一种功能性麦芽糖转运蛋白。双重破坏的转运蛋白基因并没有导致在麦芽糖培养基上生长的缺陷，也在α-淀粉酶的生产，可能是由于一个显着较低的转录水平的prologous转运蛋白基因。

Two paralogous gene clusters that are deduced to be involved in maltose assimilation exist in the genome of Aspergillus oryzae. These clusters are both consisting of three genes that each encodes a transporter, alpha-glucosidase, and a transcription factor, respectively, and one of them is functional but the other seems to be transcptionally silent. However, interestingly, these silent genes are induced to be transcribed when the functional genes are disrupted. The paralogous transporter gene was proved to encode a functional maltose transporter by complementation experiment. Double disruption of the transporter genes did not result in the defect in growth on maltose medium and also in alpha-amylase production, probably due to a significantly low transcription level of the pralogous transporter gene.