Structure and function of DNA repair enzymes

点击翻译按钮获取中文摘要

In this research project a number of novel DNA repair genes and proteins were isolated and structures of various repair proteins were determined as listed below ;1) Cyclobutane pyrimidine dimer (CPD) photolyases from various higher eukaryotes including aplacental mammals and a 6-4photoproduct (64PP) photolyase gene from Drosophila melanogaster were firstly isolated. Novel UV endonuclease genes for CPD and 64PP was isolated from eukaryotes and a procaryote.2) APEX (AP endonuclease) gene was isolated from mouse and its roles in DNA repair and development were identified.3) A human gene encoding a RecQ homolog was isolated. Disruption of a yeast homolog of the cloned human gene gave a MMS sensitive, sporulation-deficient mutant.4) A novel photosensitive human cell line like a Cockayne's syndrome (CS) was identified.5) p53 protein was found to be induced in cell lines of CS of XPA with less UV dose than in XPC or HeLa cells. It was concluded that transcription block by UV damage activates p53.6) An in vitro assay for NER was established using SV40 mini chromosome and used to isolate XPC and HHR23 genes. Furthermore, the association of both gene products was found to be essential for NER activity.7) Structures of repair proteins, RUVC,XPA,T4 CPD glycosylase, 3-methyl adenine glycosylase and CPD photolyase, were firstly determined.