GENETIC EFFECTS OF PHOTOADDUCTS AND PHOTOCROSS-LINKS IN DNA OF PHAGE-LAMBDA EXPOSED TO 360 NM LIGHT AND TRI-METHYLPSORALEN OR KHELLIN
GENETIC EFFECTS OF PHOTOADDUCTS AND PHOTOCROSS-LINKS IN DNA OF PHAGE-LAMBDA EXPOSED TO 360 NM LIGHT AND TRI-METHYLPSORALEN OR KHELLIN
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DOI：
10.1016/0005-2787(77)90319-7
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发表时间：
1977-01-01
期刊：
影响因子：
--
通讯作者：
HOWARDFLANDERS, P
中科院分区：
文献类型：
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作者：
CASSUTO, E;GROSS, N;HOWARDFLANDERS, P
呋喃香豆素4，5‘’，8-三甲基补骨脂素使细胞和病毒对360 nm的光敏感，在它们的DNA中产生交联链和单加合物。呋喃黄色素是一种不如补骨脂素有效的增敏剂，但也能在DNA中诱导交联键和加合物。交联链的数量随着暴露于光的时间的平方而增加。Khellin比补骨脂素需要更大的影响，可能是因为远端不饱和键的角度对相邻碱基对的交联嘧啶不太有利。通过调整360 nm光的曝光时间，λ。用补骨脂素和Khellin破坏噬菌体以产生相同数量的交联物。这些暴露产生的[~3H]khellin是噬菌体DNA中[~3H]补骨脂素加合物的8倍。用非放射性光敏剂进行类似的曝光，以确定.lambda的有效性。在产生基因重组体时携带交联链和单加合物的噬菌体。用补骨脂素和昆兰蛋白受损的噬菌体进行噬菌体-噬菌体遗传杂交，在抑制条件下阻止受损DNA的复制。交叉链接是.apprx。在复压条件下，诱导重组的效率是单加合物的20倍。对野生型细菌[大肠杆菌]的空斑形成能力的存活测试表明，交联物是.apprx。比加合物有效15倍。因此，在补骨脂素受损的同种免疫杂交中。感染野生型溶原菌的噬菌体3/4的诱导重组可以归因于交联链而不是单加合物。
The furocoumarin 4,5'',8-trimethylpsoralen sensitizes cells and viruses to 360 nm light, producing cross-links and monoadducts in their DNA. The furanochromone khellin is a less effective sensitizing agent than psoralen, but also induces cross-links and adducts in DNA. The number of cross-links increases as the square of the time of exposure to light. Greater fluences were required for khellin than for psoralen, possibly because of the less favorable angle of the distal unsaturated bonds for cross-linking pyrimidines in adjacent base pairs. By adjusting the time of exposure to 360 nm light, .lambda. phages were damaged with [3H]psoralen and [3H]khellin to produce equal numbers of cross-links. These exposures produced 8-times more [3H]khellin than [3H]psoralen adducts in the DNA of the phages. Similar exposures were made with nonradioactive photosensitizers to determine the effectiveness of .lambda. phages carrying cross-links and monoadducts in producing genetic recombinants. Phage-prophage genetic crosses were performed with psoralen and khellin-damaged phages under repressed conditions in which replication of the damaged DNA was blocked. Cross-links were .apprx. 20-times more effective than monoadducts for inducing recombination under repressed conditions. Tests on the survival of plaque forming ability on wild type bacteria [Escherichia coli], showed that cross-links were .apprx. 15-times more effective than the adducts. Thus in homoimmune crosses with psoralen-damaged .lambda. phages infecting wild type lysogens > 3/4 of the induced recombination can be attributed to cross-links rather than to monoadducts.