RECJ PROTEIN INTERACTIONS

细胞采用许多DNA修复和突变避免机制来保护遗传完整性。 如果没有这些重要的过程，细胞就会发生突变、染色体畸变或死亡。 修复缺陷的人类综合征已被确定，包括神经和免疫缺陷，癌症倾向和过早衰老。许多DNA修复和突变避免机制的一个共同特征是DNA的降解，由DNA外切核酸酶蛋白完成。 核酸外切酶切除有害的DNA损伤或复制错误，并促进断裂染色体的重组修复。 核酸外切酶还可以防止导致突变的不适当的基因重排。 当细胞面临DNA损伤时，核酸外切酶产生细胞分裂停滞的分子信号。 对DNA重组、修复和诱变的分子理解将需要参与这些过程的核酸外切酶的知识。 我们的目的是确定重组和修复E.大肠杆菌和酿酒酵母。 我们试图了解它们的生化特性，它们的分子伴侣以及它们在体内发挥的作用。从E.大肠杆菌一直是我们之前研究的重点。 我们已经表明，RecJ是在古细菌，真细菌和真核生物中发现的蛋白质大家族的成员。 我们将继续分析这种蛋白质的结构和功能。 将测定RecJ核酸外切酶与参与DNA复制或修复的其他蛋白质的物理或功能相互作用。我们从大肠杆菌中鉴定出两种新的核酸外切酶。杆菌 我们将继续描述它们的生物化学特性，并分析这些核酸外切酶的突变体的遗传稳定性、重组和DNA修复缺陷。 由于很明显，这些功能中的一些在遗传上是多余的，因此将评估这些和其他基因中的多个突变体的遗传特性。将在ssExo突变体中进行DNA修复的物理监测和SOS调节的评估。 第三种推定的DNA外切核酸酶来自E.将测定大肠杆菌对寡核苷酸的活性。 突变体和遗传抑制这一功能的特点。我们将研究来自酿酒酵母的推定的3'核酸外切酶（基于序列相似性）的作用。这些基因将在E.大肠杆菌，以验证它们是否编码核酸外切酶。 将检查保留残留物中的突变体的生物学效应。

Cells employ numerous DNA repair and mutation avoidance mechanisms to protect genetic integrity. In the absence of these important processes, cells suffer mutations, chromosomal aberrations or death. Repair-deficient human syndromes have been identified and include neurological and immunological defects, cancer-proneness and premature aging. One common feature of many DNA repair and mutation avoidance mechanisms is the degradation of DNA, accomplished by DNA exonuclease proteins. Exonucleases excise offending DNA lesions or replication errors and promote recombinational repair of broken chromosomes. Exonucleases also prevent inappropriate genetic rearrangements that lead to mutation. Exonucleases produce molecular signals for cell division arrest when the cell is confronted with DNA damaged. A molecular understanding of DNA recombination, repair and mutagenesis will require knowledge of the exonucleases that participate in these processes. Our objective is to define recombination and repair exonucleases of E. coli and Saccharomyces cereviseae. We seek to understand their biochemical properties, their molecular partners and what roles they play in vivo. The RecJ exonuclease from E. coli has been the focus of much of our previous investigation. We have shown that RecJ is a member of a large family of proteins found in archaebacteria, eubacteria and eukaryotes. We will continue to analyze the structure and function of this protein. Physical or functional interactions of RecJ exonuclease with other proteins involved in DNA replication or repair will be assayed. We have identified two new exonucleases from the bacterium E. coli. We will continue to characterize their biochemistry and will analyze mutants in these exonucleases for genetic stability, recombination and DNA repair defects. As it is clear that some of these functions are genetically redundant, multiple mutants in these and other genes will assessed for genetic properties. Physical monitoring of DNA repair and assessment of SOS regulation will be performed in ssExo mutants. A third putative DNA exonuclease from E. coli will be assayed for activity on oligonucleotides. Mutants and genetic suppressors of this function will be characterized. We will investigate the role of putative 3' exonucleases (based on sequence similarity) from the yeast Saccharomyces cerevisiae. The genes will be expressed in E. coli to verify if they encode exonucleases. Mutants in conservied residues will be examined for biological effects.