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

米曲霉基因组中存在两个与麦芽糖同化相关的同源基因簇。这两个簇都由三个基因组成，每个基因分别编码一个转运体、一个α-葡萄糖苷酶和一个转录因子，其中一个是有功能的，但另一个似乎是超越沉默的。然而，有趣的是，当功能基因被破坏时，这些沉默的基因会被诱导转录。通过互补实验证明，该基因编码了一个功能性麦芽糖转运蛋白。转运蛋白基因的双重破坏没有导致麦芽糖培养上的生长缺陷和α-淀粉酶的产生，这可能是由于转运蛋白基因的转录水平显著降低所致。

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.