Studies Of Immunoglobulin Gene Rearrangement

免疫球蛋白基因重排的研究

• 批准号: 7337457
• 负责人: MARTIN F. GELLERT
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7337457
• 关键词: Studies; Immunoglobulin; Gene; Rearrangement

Our research on V(D)J recombination, the rearrangement of gene segments that is used to assemble intact immunoglobulin and T cell receptor coding regions, has continued in the past year. This process is initiated by a bipartite recombinase made up of the RAG1 and RAG2 proteins, which act together to introduce double-stranded breaks into the DNA adjacent to the coding segments. In the same raction they convert the ends of the coding DNA into covalently joined DNA hairpins. Similar hairpins are formed by some related transposases, such as the large group of eukaryotic hAT transposases. and we are following up this analogy to try to explain the large distortion of DNA structure that is necessary to make hairpinning possible. We have identified two tryptophan residues that may be involved in binding a base extruded from the DNA, thus making the DNA more flexible. In support of this model, we have found that removal of a critical base at the cleavage site ( to generate an abasic structure) allows cutting of the DNA under conditions where it would not normally occur, and can also rescue tryptophan mutations that otherwise block cleavage. Work is also continuing on constructing variants of the RAG1 and RAG2 proteins, to be tested for their ability to crystallize in a specific complex with DNA.

我们对V(D)J重组（用于组装完整免疫球蛋白和T细胞受体编码区的基因片段的重排）的研究在过去一年中一直在继续。这个过程是由RAG1和RAG2蛋白组成的两部分重组酶启动的，它们共同作用，将双链断裂引入编码片段附近的DNA。在同样的反应中，它们将编码DNA的末端转化为共价连接的DNA发夹。类似的发夹是由一些相关的转座酶形成的，例如真核生物hAT转座酶的大群。我们正在继续这个类比，试图解释DNA结构的巨大扭曲，这是使发夹成为可能所必需的。我们已经确定了两个色氨酸残基，它们可能参与结合从DNA中挤出的碱基，从而使DNA更灵活。为了支持这一模型，我们发现在切割位点移除一个关键的碱基（以产生一个基本结构）可以在通常不会发生的情况下切割DNA，并且还可以挽救色氨酸突变，否则会阻断切割。