Formation and biological functions of unusual DNA/RNA structures formed by repeat sequences.

由重复序列形成的不寻常 DNA/RNA 结构的形成和生物学功能。

• 批准号: RGPIN-2016-06355
• 负责人: Pearson, Christopher
• 金额: $ 2.77万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=710258
• 关键词: Formation; biological; functions; unusual; DNA

More than 50% of most genomes are tandem repetitive DNA sequences, including telomeres, centromeres, macro-, mini- and microsatellite repeats. Repeat DNAs can exist in unusual structures beyond the canonical right-handed B-form double helix. The specific locations of repeats in genes and chromosomes highlight their biological importance, particularly with respect to the unusual structures they form. Evidence indicates that repeat structures play roles in gene regulation, splicing, recombination, epigenetic regulation, repeat length mutation, etc. Functions are likely to be reflected by the biophysical structures formed by the repeats. Importantly, the length of the repeat tracts are hyper-prone to change and these length changes can dramatically affect their biological function. Length changes likely involve unusual structures. Our goal is to understand unusual repeat structures and how they can change lengths. The formation of unusual repeat structures likely occurs during DNA replication, repair, recombination and transcription, when complementary strands become unpaired and single-stranded. Slipped-DNAs form by out-of-register misalignment of repeats. Newly transcribed RNAs can form unusual structures such as intra-strand hairpins and G-quadruplexes. Some DNA sequences can form transcriptionally induced RNA:DNA hybrids called R-loops. The specific locations of these sequences in genes and chromosomes highlight their biological importance, particularly with respect to the alternative structures they form, which are highly likely to have functional roles. These functions are poorly understood. Most structural analyses are performed on isolated DNA strands in the absence of their partner strand. Furthermore, most studies use short synthetic oligo repeats that are dramatically shorter than their biological counter-parts, which occur in the presence of both complementary strands. Such studies yield results that may only partially reflect what may occur biologically. A thorough understanding of the structures formed by these repeats, the proteins that interact and process them, must include studies using biologically relevant lengths of the complementary strands. With a focus upon a broad range of repeats (telomeres, centromeres, macro-, mini-, and micro-satellite repeats), that are and are not associated with disease, we will study the formation of unusual structures by the repeats; assess protein-nucleic acid interactions, as well as the roles of certain proteins in processing these unusual structures to repeat length changes. This proposal focuses upon the basic fundamental molecular and biological aspects of repeat sequences. The results of this proposal will shed light upon both the natural and disease related aspects of some of these repeats. Disease-related studies on a subset of the repeats studied herein are the focus of other grants.

大多数基因组中超过50%是串联重复DNA序列，包括端粒、着丝粒、宏、迷你和微卫星重复序列。重复dna可以存在于规范的右手b型双螺旋结构之外的不寻常结构中。重复序列在基因和染色体中的特定位置突出了它们的生物学重要性，特别是它们形成的不寻常结构。有证据表明，重复序列结构在基因调控、剪接、重组、表观遗传调控、重复序列长度突变等方面发挥着重要作用。功能可能由重复序列形成的生物物理结构反映出来。重要的是，重复束的长度非常容易发生变化，这些长度的变化会极大地影响它们的生物学功能。长度变化可能涉及不寻常的结构。我们的目标是了解不寻常的重复结构以及它们如何改变长度。