Yuan Xiao-Lian, van der Kaaij Rachel M, van den Hondel Cees A M J J, Punt Peter J, van der Maarel Marc J E C, Dijkhuizen Lubbert, Ram Arthur F J
Clusius Laboratory, Molecular Microbiology and Kluyver Centre for Genomics of Industrial Fermentations, Institute of Biology Leiden, Leiden University, Leiden, The Netherlands.
Mol Genet Genomics. 2008 Jun;279(6):545-61. doi: 10.1007/s00438-008-0332-7. Epub 2008 Mar 5.
The filamentous ascomycete Aspergillus niger is well known for its ability to produce a large variety of enzymes for the degradation of plant polysaccharide material. A major carbon and energy source for this soil fungus is starch, which can be degraded by the concerted action of alpha-amylase, glucoamylase and alpha-glucosidase enzymes, members of the glycoside hydrolase (GH) families 13, 15 and 31, respectively. In this study we have combined analysis of the genome sequence of A. niger CBS 513.88 with microarray experiments to identify novel enzymes from these families and to predict their physiological functions. We have identified 17 previously unknown family GH13, 15 and 31 enzymes in the A. niger genome, all of which have orthologues in other aspergilli. Only two of the newly identified enzymes, a putative alpha-glucosidase (AgdB) and an alpha-amylase (AmyC), were predicted to play a role in starch degradation. The expression of the majority of the genes identified was not induced by maltose as carbon source, and not dependent on the presence of AmyR, the transcriptional regulator for starch degrading enzymes. The possible physiological functions of the other predicted family GH13, GH15 and GH31 enzymes, including intracellular enzymes and cell wall associated proteins, in alternative alpha-glucan modifying processes are discussed.
丝状子囊菌黑曲霉以其能够产生多种用于降解植物多糖物质的酶而闻名。这种土壤真菌的主要碳源和能源是淀粉，淀粉可分别由糖苷水解酶（GH）家族13、15和31的成员α-淀粉酶、葡糖淀粉酶和α-葡萄糖苷酶协同作用降解。在本研究中，我们将黑曲霉CBS 513.88的基因组序列分析与微阵列实验相结合，以鉴定这些家族中的新酶并预测它们的生理功能。我们在黑曲霉基因组中鉴定出17种先前未知的GH13、15和31家族的酶，所有这些酶在其他曲霉菌中都有直系同源物。新鉴定的酶中只有两种，一种假定的α-葡萄糖苷酶（AgdB）和一种α-淀粉酶（AmyC），被预测在淀粉降解中起作用。所鉴定的大多数基因的表达不受麦芽糖作为碳源的诱导，也不依赖于淀粉降解酶的转录调节因子AmyR的存在。本文讨论了其他预测的GH13、GH15和GH31家族酶，包括细胞内酶和细胞壁相关蛋白，在替代性α-葡聚糖修饰过程中的可能生理功能。
