The role of Q motif in superfamily 2 DNA helicases

Q 基序在超家族 2 DNA 解旋酶中的作用

• 批准号: 418480-2012
• 负责人: Wu, Yuliang
• 金额: $ 2.26万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=551437
• 关键词: role; motif; superfamily; DNA; helicases

DNA helicases are ATP-dependent motor proteins that unwind duplex DNA to form single stranded DNA intermediates that are required for DNA metabolism in all organisms. Superfamily 2 (SF2) is the largest of six helicase families. The conversion of energy derived from ATP hydrolysis into unwinding of double-stranded nucleic acids is coordinated by seven sequence motifs (I, Ia, II, III, IV, V, and VI). The Q motif is located upstream of motif I and consists of a nine amino acid sequence (GFXXPXPIQ) containing an invariant glutamine (Q) residue. Although increasing evidences suggest that the Q motif is essential for helicase function, the role of Q motif is less appreciated compared with the seven conserved helicase motifs. Our biochemical and genetic analyses demonstrate that the Q motif in FANCJ helicase is essential for its helicase activity and DNA repair function in vivo by regulation of the dimerization of FANCJ protein, which is a novel function for the Q motif. It remains unknown whether such function is conserved in FANCJ-like helicases (ChlR1 and RTEL1) and the RecQ helicase family, which all contain the Q motif in their primary sequence. Using a combination of structural, biochemical, and cellular approaches, our studies aim to 1) Continue to define the role of the Q motif in the FANCJ helicase, 2) Examine the role of the Q motif in the FANCJ-like helicases ChlR1 and RTEL1, and 3) Determine the functional and structural roles of the Q motif in the RecQ helicase family. The results obtained from this study will advance fundamental knowledge of structural elements of SF2 DNA helicases, which play vital roles in DNA replication, repair, recombination, transcription, chromosome segregation, and telomere maintenance that conserved from archaea, bacteria, to eukaryotes.

DNA解旋酶是一种依赖于ATP的马达蛋白，它能解开双链DNA，形成DNA代谢所需的单链DNA中间体。超家族2(SF2)是六个解旋酶家族中最大的一个。从ATP水解产生的能量转换为双链核酸的解离是由七个序列基序(I、Ia、II、III、IV、V和VI)协调的。Q基序位于基序I的上游，由一个含有不变谷氨酰胺(Q)残基的九个氨基酸序列(GFXXPXPIQ)组成。虽然越来越多的证据表明Q基序是解旋酶功能所必需的，但与7个保守的解旋酶基序相比，Q基序的作用还不是很清楚。我们的生化和遗传分析表明，FANCJ解旋酶中的Q基序是通过调节FANCJ蛋白的二聚化来调节其解旋酶活性和体内DNA修复功能的，这是Q基序的一个新功能。目前尚不清楚这一功能是否在FANCJ样解旋酶(ChlR1和RTEL1)和RecQ解旋酶家族中保守，这两个解旋酶家族的初级序列都含有Q基序。我们的研究采用结构、生化和细胞相结合的方法，旨在1)继续确定Q基序在FANCJ解旋酶中的作用，2)研究Q基序在FANCJ样解旋酶ChlR1和RTEL1中的作用，3)确定Q基序在RecQ解旋酶家族中的功能和结构作用。这项研究的结果将促进对SF2 DNA解旋酶结构元件的基础知识，这些结构元件在从古菌、细菌到真核生物的DNA复制、修复、重组、转录、染色体分离和端粒维持中发挥重要作用。