INVOLVEMENT OF HELICASE-II (UVRD GENE-PRODUCT) AND DNA-POLYMERASE-I IN EXCISION MEDIATED BY THE UVRABC PROTEIN COMPLEX
INVOLVEMENT OF HELICASE-II (UVRD GENE-PRODUCT) AND DNA-POLYMERASE-I IN EXCISION MEDIATED BY THE UVRABC PROTEIN COMPLEX
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DOI：
10.1073/pnas.82.15.4925
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发表时间：
1985-01-01
影响因子：
11.1
通讯作者：
GROSSMAN, L
中科院分区：
文献类型：
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作者：
CARON, PR;KUSHNER, SR;GROSSMAN, L
由大肠杆菌uvrABC蛋白复合物催化的紫外线照射DNA反应的双峰切口性质可能导致12至13个核苷酸长的受损片段被切除。含有紫外线诱导的嘧啶二聚体的寡核苷酸片段在非变性的体外反应条件下不释放。此外，uvrABC蛋白与切割的DNA稳定结合，并且在切割事件发生后不会翻转。结果表明，当同时催化三磷酸脱氧核苷底物聚合时，受损片段从亲本uvrabc切割的DNA中释放取决于螯合条件或同时添加uvrD基因产物（解旋酶II）和polA基因产物（DNA聚合酶I）。这种多蛋白催化的一系列反应的产物作为多核苷酸连接酶的底物，导致DNA链完整性的恢复。将uvrD蛋白添加到切割的DNA-uvrABC复合体中也会导致uvrC蛋白的周转。这表明，切口、切除、再合成和结扎的修复过程是由修复体结构中的蛋白质复合物协调催化的。
The bimodal-incision nature of the reaction of UV-irradiated DNA catalyzed by the Escherichia coli uvrABC protein complex potentially leads to excision of a 12- to 13-nucleotide-long damaged fragment. The oligonucleotide fragment containing the UV-induced pyrimidine dimer is not released under nondenaturing in vitro reaction conditions. Also, the uvrABC proteins are stable bound to the incised DNA and do not turn over after the incision event. It is shown that release of the damaged fragment from the parental uvrABC-incised DNA is dependent upon either chelating conditions or the simultaneous addition of the uvrD gene product (helicase II) and the polA gene product (DNA polymerase I) when polymerization of deoxynucleoside triphosphate substrates is concomitantly catalyzed. The product of this multiprotein-catalyzed series of reactions serves as a substrate for polynucleotide ligase, resulting in the restoration of the integrity of the strands of DNA. The addition of the uvrD protein to the incised DNA-uvrABC complex also results in turnover of the uvrC protein. It is suggested that the repair processes of incision, excision, resynthesis and ligation are coordinately catalyzed by a complex of proteins in a repairosome configuration.