Heterotypic transcriptional condensates formed by prion-like paralogous proteins canalize flowering transition in tomato

第一作者：Xiaozhen Huang

第一单位：中科院遗传与发育生物学研究所

通讯作者：Cao Xu

 Abstarct 

背景+问题：Paralogs that arise from gene duplications during genome evolution enable genetic redundancy and phenotypic robustness. Variation in the coding or regulatory sequence of paralogous transcriptional regulators diversifies their functions and relationships, which provides developmental robustness against genetic or environmental perturbation. The fate transition of plant shoot stem cells for flowering and reproductive success requires a robust transcriptional control. However, how paralogs function and interact to achieve such robustness is unknown. 

基因组演化过程中基因复制所产生的旁系同源基因为遗传冗余和表型稳健性提供基础。旁系同源转录调控基因编码区或调控区域的变异使其功能和相互关系更加多样化，从而为生物在应对遗传和环境扰动时的发育稳健性提供保障。植物开花和生殖成功的茎干细胞命运转变需要一个稳健的转录控制。但是，旁系同源如何发挥功能以及相互作用以达到如此稳健性还不清楚。

主要发现：Here, we explore the genetic relationship and protein behavior of ALOG family transcriptional factors with diverse transcriptional abundance in shoot meristems. 

本文中，作者研究了ALOG家族转录调控子的遗传关系和蛋白行为，该家族的成员在茎分生组织具有不同转录水平。

结果1-ALOG功能冗余：A mutant spectrum covers single and higher-order mutant combinations of five ALOG paralogs and creates a continuum of flowering transition defects, showing gradually enhanced precocious flowering, along with inflorescence simplification from wild-type-like to progressively fewer flowers until solitary flower with sterile floral organs. Therefore, these paralogs play unequal roles and act together to achieve a robust genetic canalization. 

作者通过对5个ALOG旁系同源基因的单阶和各种组合的高阶突变，创制了一批具有连续成花转变缺陷的突变体，表现出连续增强的早花表型，同时伴随着花序的简化，从野生型的完整花序到花序的逐渐较少，直到育性丧失的单生花。因此，这些旁系同源基因的作用并非等价，而是共同作用以达到稳健的遗传渠化。

结果2-ALOG功能分化与保守：All five proteins contain prion-like intrinsically disordered regions (IDRs) and undergo phase separation. Accumulated mutations following gene duplications lead to IDR variations among ALOG paralogs, resulting in divergent phase separation and transcriptional regulation capabilities. Remarkably, they retain the ancestral abilities to assemble into a heterotypic condensate that prevents precocious activation of the floral identity gene ANANTHA. 

所有的5个ALOG旁系同源基因都含有prion-like的内在无序蛋白域IDRs，并且经历了相分离。基因复制后随着突变的积累，导致ALOG不同旁系同源基因之间的IDRs发生变异，最终导致不同的相分离和转录调控能力。值得注意的是，这些ALOG旁系同源基因都保留了祖先基因的功能，可以组装成一个异源凝聚物，以防止花组织特征基因ANANTHA的提前激活。

结论：Our study reveals a novel genetic canalization mechanism enabled by heterotypic transcriptional condensates formed by paralogous protein interactions and phase separation, uncovering the molecular link between gene duplication caused IDR variation and robust transcriptional control of stem cell fate transition.

本文的研究结果揭示了一种由旁系同源蛋白相互作用和相分离形成的异源转录凝聚物构成的遗传渠化机制，发现了由基因复制导致的IDR变异与干细胞命运转变的稳健转录控制之间的分子联系。

** 许操 **

doi: https://doi.org/10.1186/s13059-022-02646-6

Journal: Genome Biology

Published date: March 14, 2022​