Institute of Molecular Biology, Academia Sinica, Taipei, 115, Taiwan.
Taiwan International Graduate Program in Molecular and Cellular Biology, Academia Sinica, Taipei, 115, Taiwan.
Appl Microbiol Biotechnol. 2018 Feb;102(4):1567-1574. doi: 10.1007/s00253-017-8731-5. Epub 2018 Jan 8.
Trichoderma reesei (syn. Hypocrea jecorina) is a filamentous ascomycete. Due to its capability of producing large amounts of lignocellulolytic enzymes and various heterologous proteins, this fungus has been widely used for industrial applications for over 70 years. It is also a model organism for lignocellulosic biomass degradation and metabolic engineering. Recently, we experimentally and computationally demonstrated that Trichoderma reesei exhibits high homology pairing and repeat-induced point (RIP) mutation activities at a premeiotic stage, i.e., between fertilization and karyogamy or premeiotic DNA replication. The discovery of RIP in Trichoderma reesei not only reveals significant impacts of sexual reproduction on evolution and chromosome architecture but also provides intriguing perspectives for industrial strain improvement. This review emphasizes two major points about RIP and RIP-like processes in Pezizomycotina fungi. First, the molecular mechanisms of RIP and RIP-like processes in Trichoderma reesei and other Pezizomycotina fungi are apparently distinct from those originally described in the model fungus Neurospora crassa. Second, orthologs of the rid1 (deficient in RIP-1) DNA methyltransferase gene were shown to be essential for sexual development in at least four Pezizomycotina fungi, including Trichoderma reesei. In contrast, rid1 is dispensable for Neurospora crassa sexual development. We suggest that the rid1-like gene products and/or their DNA methyltransferase activities play critical roles in promoting fungal sexual development. The Neurospora crassa rid1 gene might have lost this evolutionarily conserved function.
里氏木霉（Syn. Hypocrea jecorina）是一种丝状子囊菌。由于其能够产生大量木质纤维素酶和各种异源蛋白，这种真菌在工业应用中已经得到了广泛的应用，超过 70 年。它也是木质纤维素生物质降解和代谢工程的模式生物。最近，我们通过实验和计算证明，里氏木霉在减数分裂前阶段（即受精和核融合或减数分裂前 DNA 复制之间）表现出高度同源配对和重复诱导点（RIP）突变活性。在里氏木霉中发现 RIP 不仅揭示了有性繁殖对进化和染色体结构的重大影响，而且为工业菌株改良提供了有趣的视角。本文重点介绍了 Pezizomycotina 真菌中的 RIP 和 RIP 样过程的两个主要方面。首先，里氏木霉和其他 Pezizomycotina 真菌中 RIP 和 RIP 样过程的分子机制与最初在模式真菌 Neurospora crassa 中描述的机制明显不同。其次，rid1（RIP-1 缺陷）DNA 甲基转移酶基因的同源物对于至少四种 Pezizomycotina 真菌的有性发育是必不可少的，包括里氏木霉。相比之下，rid1 对于 Neurospora crassa 的有性发育是可有可无的。我们认为，rid1 样基因产物及其 DNA 甲基转移酶活性在促进真菌有性发育中起着关键作用。Neurospora crassa 的 rid1 基因可能已经失去了这种进化保守的功能。
