Prediction of RNA-RNA Interactions by Kinetic Modelling

生物体转录组的大部分不是由编码RNA的蛋白质组成，而是代表所谓的非编码RNA(NcRNA)，其中大多数作为调节元件。其中许多ncRNA分子需要与编码蛋白质的信使RNA或其他ncRNA相互作用才能完成它们的调节功能。对这些RNA-RNA相互作用的详细了解有助于深入了解生物体的调控网络。由于实验研究的复杂性和成本，迫切需要计算预测方法。目前的方法通常局限于简单的相互作用类型，预测精度较低。在本项目中，我们将识别约束已知相互作用的空间和拓扑特征，以提高RNA-RNA相互作用预测模型的预测质量。此外，我们将定义新的模型，涵盖更一般的交互模式，直至多站点交互。识别出的特征将被整合为硬约束，以避免不现实的结构，并通过伪能量项更好地指导应用的优化方法。这将伴随着对RNA-RNA相互作用动力学的广泛研究，因为它能够将相互作用的形成引导到不可预测的、次优结构。因此，将定义和实施新的能源景观模型，以允许对基于能源景观的动力学进行详细但仍可计算的研究。这包括开发新的方法来有效地探索大能量景观以及计算过渡模型和运动学。这两个研究领域被连接到新的RNA-RNA相互作用预测管道中，该管道将尊重新的结构约束并考虑定义相互作用形成的动力学效应。我们将应用我们的新管道来研究ncRNAs的相互作用网络，筛选调控ncRNAs的靶点，并增加对某些结合途径的机制细节的了解。应用的一个方向将是研究反义RNA相互作用的机制细节。反义RNA广泛存在于原核生物和真核生物的转录组中，但对其调控作用知之甚少。一个特别有趣的话题是确定反义转录本实际上在多大程度上与它们各自的正义转录本形成双链，以及可能的调控机制。我们的计算研究将得到湿实验室实验的支持。除了新的见解外，该项目旨在开发一个大型工具集来促进这一领域的进一步研究。这些目标结果不仅支持了RNA-RNA相互作用的研究，而且也为单分子的结构预测以及其他体系的高能景观的动力学研究提供了可能。

The majority of an organism's transcriptome does not consist of protein encoding RNA but represents so called non-coding RNA (ncRNA), most of them acting as regulatory elements. Many of these ncRNA molecules require interactions with protein-coding messenger RNAs or other ncRNAs to fulfill their regulatory functions. A detailed understanding of these RNA-RNA interactions gives insight into the regulatory networks of organisms.Due to the complexity and expense for experimental studies, there is a strong need for computational prediction approaches. Current methods are usually restricted to simple interaction types and show a low prediction accuracy.Within this project we will identify steric and topological features constraining known interactions to increase prediction quality of RNA-RNA interaction prediction models. Furthermore, we will define new models covering more general interaction patterns up to multi-site interactions. Identified features will be integrated both as hard constraints to avoid unrealistic structures and via pseudo energy terms for a better guiding of the applied optimization methods.This will be accompanied with an extensive research of the kinetics of RNA-RNA interactions, since it is able to guide the interaction formation to non-predictable, suboptimal structures. Therefore, new energy landscape models will be defined and implemented that allow for a detailed but still computationally accessible study of the energy landscape based kinetics. This includes the development of new methods for an efficient exploration of large energy landscapes as well as for the computation of transition model and kinetics.These two research fields are joined within new RNA-RNA interaction prediction pipelines that will respect the new structure constraints as well as account for kinetic effects defining the interaction formation. We will apply our new pipelines to investigate interaction networks for ncRNAs, to screen for targets of regulating ncRNAs, and to increase knowledge of the mechanistic details of certain binding pathways.One direction of application will be the investigation of the mechanistic details of anti-sense RNA interactions. Anti-sense RNAs are found in great extent in the transcriptome of pro- and eukaryotes while there is only limited knowledge about their regulatory impact. An especially interesting topic is to determine to what extent anti-sense transcripts actually form duplexes with their respective sense transcripts and what regulatory mechanisms are possible. Our computational studies will be supported by wet-lab experiments.Beside new insights, the project aims at the development of a large tool set to promote further research in this field. The targeted results do not only support RNA-RNA interaction studies but also enable progress for structure prediction of single molecules as well as kinetics studies of large energy landscapes of other systems.