GENETIC INSTABILITY IN YEAST

产品说明：在多种生物体中，导致DNA复制酶耗尽的突变增加了遗传不稳定性的发生率--特征在于重组缺失和/或染色体丢失率升高的事件。 沃纳综合征（WS）的许多细胞表型表明，它属于这类遗传缺陷的福尔斯。 Werner综合征基因WRN最近被克隆和测序，并被发现编码RecQ家族的DNA解旋酶。 申请人提出，在WRN解旋酶不存在下进行复制的细胞在DNA中留下损伤，所述损伤通过产生基因组重排的重组系统修复。 他们计划在酵母中探索这种可能性，通过寻找在缺乏酵母WRN解旋酶同源物Sgs 1 p的情况下可能产生的特定类型的复制缺陷。 此外，通过研究在缺乏Sgs 1蛋白的酵母细胞中诱导的重组事件的类型，并通过寻找与正常WRN和Sgs 1解旋酶相互作用的蛋白质，他们希望深入了解在没有这种解旋酶的情况下复制机制产生的主要损伤类型。与人类蛋白质同源的酵母蛋白质的鉴定以及在酵母中对其进行遗传学研究的能力已经导致了对导致人类疾病的许多过程的理解。 由于S.酿酒酵母--最近已全部测序--在复制过程中对染色体进行物理分析是相当可行的。在其他真核生物中，复制起始的顺式作用元件和反式作用蛋白质没有像在酵母中那样得到很好的表征。 此外，基因组易于操作，使酵母成为研究基本染色体生物学的理想宿主。 最后，酵母提供了一个用户友好的细胞环境中，研究蛋白质-蛋白质相互作用的方式的双杂交转录报告系统。

DESCRIPTION: (Applicant's Description) In a variety of organisms, mutations that cause depletion of DNA replication enzymes increase the incidence of genetic instability-- events that are characterized by elevated rates of recombination deletion, and/or chromosome loss. Many of the cellular phenotypes of Werner Syndrome (WS) suggest that it falls into this class of genetic defect. The Werner syndrome gene WRN was recently cloned and sequenced and was found to encode a DNA helicase of the RecQ family. The applicants propose that cells that carry out replication in the absence of the WRN helicase leave behind lesions in the DNA that are repaired by a recombination system that produces the genomic rearrangements. They plan to explore this possibility in yeast, by looking for specific types of replication defects that might be generated in the absence of the yeast WRN helicase homologue, Sgs1p. In addition, by studying the types of recombination events induced in yeast cells deficient for the Sgs1 protein, and by looking for proteins that interact with both the normal WRN and Sgs1 helicases, they hope to gain insight into the types of primary damage generated by the replication machinery in the absence of this helicase. The identification of yeast proteins with homology to human proteins and the ability to study them genetically in yeast has led to an understanding of many processes that contribute to human disease. Because of the small genome size of S. cerevisiae-- recently sequenced in its entirety-- the physical analysis of chromosomes during their replication is quite feasible. In no other eukaryotic organism have the cis-acting elements and trans-acting proteins for replication initiation been as well characterized as they have been in yeast. Moreover, the ease with which the genome can be manipulated makes yeast an ideal host organism in which to study basic chromosome biology. Finally, yeast provides a user-friendly cellular environment in which to study protein-protein interactions by way of the two-hybrid transcriptional reporter system.