Genetic Modification of Carbon Catabolite Repression in Trichoderma reesei for Improved Protein Production
Genetic Modification of Carbon Catabolite Repression in Trichoderma reesei for Improved Protein Production
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DOI：
10.1128/aem.00282-09
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发表时间：
2009-07-15
影响因子：
4.4
通讯作者：
Saloheimo, Markku
中科院分区：
文献类型：
--
作者：
Nakari-Setala, Tiina;Paloheimo, Marja;Saloheimo, Markku
研究表明，丝状真菌里氏木霉的纤维素酶和半纤维素酶基因受调控基因cre1介导的碳分解代谢抑制。在本研究中，构建了一些菌株，其中cre1基因被完全移除或被截断的突变变体cre1-1取代，该突变变体以前在RUT-C30突变株中发现，具有增强的产酶能力。与亲本菌株相比，缺失或截短cre1的里氏木霉转化子明显改变了菌落形态，形成的菌落较小，气生菌丝和孢子较少。在以葡萄糖为碳源的液体培养条件下，转化子的纤维素酶和半纤维素酶产量均降低。有趣的是，在诱导水解酶基因的介质中进行的发酵中，它们也产生了显著提高的这些水解酶的水平。这表明Cre1在非诱导和诱导条件下都是纤维素酶和半纤维素酶基因表达的调节器。在所有实验中，Delta cre1和cre1-1突变株之间没有表型差异，表明cre1-1基因实际上是一个零等位基因。本研究结果表明，cre1基因是里氏木霉提高产酶能力的菌株工程中的有效靶基因。
The cellulase and hemicellulase genes of the filamentous fungus Trichoderma reesei have been shown to be under carbon catabolite repression mediated by the regulatory gene cre1. In this study, strains were constructed in which the cre1 gene was either completely removed or replaced by a truncated mutant variant, cre1-1, found previously in the Rut-C30 mutant strain with enhanced enzyme production capability. The T. reesei transformants with either deletion or truncation of cre1 had clearly altered colony morphology compared with the parental strains, forming smaller colonies and fewer aerial hyphae and spores. Liquid cultures in a medium with glucose as a carbon source showed that the transformants were derepressed in cellulase and hemicellulase production. Interestingly, they also produced significantly elevated levels of these hydrolytic enzymes in fermentations carried out in a medium inducing the hydrolase genes. This suggests that cre1 acts as a modulator of cellulase and hemicellulase gene expression under both noninducing and inducing conditions. There was no phenotypic difference between the Delta cre1 and cre1-1 mutant strains in any of the experiments done, indicating that the cre1-1 gene is practically a null allele. The results of this work indicate that cre1 is a valid target gene in strain engineering for improved enzyme production in T. reesei.