ULTRAVIOLET-IRRADIATION OF DNA COMPLEXED WITH ALPHA-BETA-TYPE SMALL, ACID-SOLUBLE PROTEINS FROM SPORES OF BACILLUS OR CLOSTRIDIUM SPECIES MAKES SPORE PHOTOPRODUCT BUT NOT THYMINE DIMERS
ULTRAVIOLET-IRRADIATION OF DNA COMPLEXED WITH ALPHA-BETA-TYPE SMALL, ACID-SOLUBLE PROTEINS FROM SPORES OF BACILLUS OR CLOSTRIDIUM SPECIES MAKES SPORE PHOTOPRODUCT BUT NOT THYMINE DIMERS
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DOI：
10.1073/pnas.88.19.8288
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发表时间：
1991-10-01
影响因子：
11.1
通讯作者：
SETLOW, P
中科院分区：
文献类型：
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作者：
NICHOLSON, WL;SETLOW, B;SETLOW, P
紫外线照射的复合物的DNA和α/β型小，酸溶性蛋白（SASP）从枯草芽孢杆菌孢子得到的嘧啶二聚体的量减少和孢子光产物的量增加的SASP/DNA的比例增加。当SASP饱和的DNA在254 nm、30 kJ/m2下照射时，嘧啶二聚体和孢子光产物的产率分别小于总胸腺嘧啶的0.2%和8%; DNA与来自蜡状芽孢杆菌、巨大芽孢杆菌或双酶梭菌孢子的α/β型SASP的复合物也在UV照射下产生孢子光产物。然而，在防止复合物形成的条件下将这些SASP与DNA孵育或使用不形成复合物的突变SASP并不影响体外形成的光产物。这些结果表明，体内细菌孢子DNA的UV光化学是由于α/β型SASP的结合，已知这种结合导致体外DNA构象从B型变为A型。离体条件下孢子光产物的产量明显低于体内条件下，这可能与孢子中存在SASP以外的物质有关。有人建议，作为这些因素扩散出孢子萌发的第一分钟，孢子光产率变得类似于观察到的SASP/DNA复合物在体外照射。
UV irradiation of complexes of DNA and an alpha/beta-type small, acid-soluble protein (SASP) from Bacillus subtilis spores gave decreasing amounts of pyrimidine dimers and increasing amounts of spore photoproduct as the SASP/DNA ratio was increased. The yields of pyrimidine dimers and spore photoproduct were < 0.2% and 8% of total thymine, respectively, when DNA saturated with SASP was irradiated at 254 nm with 30 kJ/m2; in the absence of SASP the yields were reversed-4.5% and 0.3%, respectively. Complexes of DNA with alpha/beta-type SASP from Bacillus cereus, Bacillus megaterium, or Clostridium bifermentans spores also gave spore photoproduct upon UV irradiation. However, incubation of these SASPs with DNA under conditions preventing complex formation or use of mutant SASPs that do not form complexes did not affect the photoproducts formed in vitro. These results suggest that the UV photochemistry of bacterial spore DNA in vivo is due to the binding of alpha/beta-type SASP, a binding that is known to cause a change in DNA conformation in vitro from the B form to the A form. The yields of spore photoproduct in vitro were significantly lower than in vivo, perhaps because of the presence of substances other than SASP in spores. It is suggested that as these factors diffuse out in the first minutes of spore germination, spore photoproduct yields become similar to those observed for irradiation of SASP/DNA complexes in vitro.