Trichoderma reesei is an economically important enzyme producer with several unique meiotic features. spo11, the initiator of meiotic double-strand breaks (DSBs) in most sexual eukaryotes, is dispensable for T. reesei meiosis. T. reesei lacks the meiosis-specific recombinase Dmc1. Rad51 and Sae2, the activator of the Mre11 endonuclease complex, promote DSB repair and chromosome synapsis in wild-type and spo11Δ meiosis. DNA methyltransferases (DNMTs) perform multiple tasks in meiosis. Three DNMT genes (rid1, dim2 and dimX) differentially regulate genome-wide cytosine methylation and C:G-to-T:A hypermutations in different chromosomal regions. We have identified two types of DSBs: type I DSBs require spo11 or rid1 for initiation, whereas type II DSBs do not rely on spo11 and rid1 for initiation. rid1 (but not dim2) is essential for Rad51-mediated DSB repair and normal meiosis. rid1 and rad51 exhibit a locus heterogeneity (LH) relationship, in which LH-associated proteins often regulate interconnectivity in protein interaction networks. This LH relationship can be suppressed by deleting dim2 in a haploid rid1Δ (but not rad51Δ) parental strain, indicating that dim2 and rid1 share a redundant function that acts earlier than rad51 during early meiosis. In conclusion, our studies provide the first evidence of the involvement of DNMTs during meiotic initiation and recombination.

中文翻译：

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DNA胞嘧啶甲基转移酶差异调节里氏木霉减数分裂中的全基因组超突变和同源重组


里氏木霉是一种重要的经济酶生产者，具有多种独特的减数分裂特征。 spo11 是大多数有性真核生物中减数分裂双链断裂 (DSB) 的启动子，对于里氏木霉减数分裂来说是可有可无的。里氏木霉缺乏减数分裂特异性重组酶 Dmc1。 Rad51 和 Sae2（Mre11 核酸内切酶复合物的激活剂）可促进野生型和 spo11Δ 减数分裂中的 DSB 修复和染色体突触。 DNA 甲基转移酶 (DNMT) 在减数分裂中执行多项任务。三个 DNMT 基因（rid1、dim2 和 dimX）差异性地调节不同染色体区域的全基因组胞嘧啶甲基化和 C:G 至 T:A 超突变。我们已经确定了两种类型的DSB：I型DSB需要spo11或rid1来启动，而II型DSB不依赖于spo11和rid1来启动。 rid1（但不是dim2）对于Rad51介导的DSB修复和正常减数分裂至关重要。 rid1 和 rad51 表现出位点异质性 (LH) 关系，其中 LH 相关蛋白通常调节蛋白质相互作用网络中的互连性。这种LH关系可以通过删除单倍体rid1Δ（但不是rad51Δ）亲本菌株中的dim2来抑制，这表明dim2和rid1共享一个冗余功能，该功能在早期减数分裂期间比rad51更早发挥作用。总之，我们的研究提供了 DNMT 参与减数分裂起始和重组过程的第一个证据。