Sector of Molecular and Genetic Mechanisms of Regeneration, Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia.
Novosibirsk State University, Novosibirsk, Russia.
Genome Biol Evol. 2023 Sep 4;15(9). doi: 10.1093/gbe/evad161.
Retroviruses originated from long terminal repeat retrotransposons (LTR-RTs) through several structural adaptations. One such modification was the arrangement of an additional ribonuclease H (aRH) domain next to native RH, followed by degradation and subfunctionalization of the latter. We previously showed that this retrovirus-like structure independently evolved in Tat LTR-RTs in flowering plants, proposing its origin from sequential rearrangements of ancestral Tat structures identified in lycophytes and conifers. However, most nonflowering plant genome assemblies were not available at that time, therefore masking the history of aRH acquisition by Tat and challenging our hypothesis. Here, we revisited Tat's evolution scenario upon the aRH acquisition by covering most of the extant plant phyla. We show that Tat evolved and obtained aRH in an ancestor of land plants. Importantly, we found the retrovirus-like structure in clubmosses, hornworts, ferns, and gymnosperms, suggesting its ancient origin, broad propagation, and yet-to-be-understood benefit for the LTR-RTs' adaptation.
逆转录病毒起源于长末端重复逆转座子（LTR-RTs），通过几种结构适应。这样的一种修饰是在天然 RH 旁边排列额外的核糖核酸酶 H（aRH）结构域，随后后者降解和亚功能化。我们之前表明，这种类似于逆转录病毒的结构在开花植物中的 Tat LTR-RTs 中独立进化，提出其起源于在石松类和松柏类中鉴定的祖先 Tat 结构的顺序重排。然而，当时大多数非开花植物基因组组装不可用，因此掩盖了 Tat 通过 Tat 获得 aRH 的历史，并挑战了我们的假设。在这里，我们通过涵盖大多数现存的植物门重新审视了 Tat 在获得 aRH 后的进化情况。我们表明，Tat 在陆地植物的祖先中进化并获得了 aRH。重要的是，我们在石松类、角苔类、蕨类和裸子植物中发现了类似于逆转录病毒的结构，这表明它具有古老的起源、广泛的传播，以及对 LTR-RTs 适应的尚未理解的好处。
