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
- Univ. of Connecticut Health Center, Farmington (United States)
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/m{sup 2}; 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.
- OSTI ID:
- 5603049
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America; (United States), Vol. 88:19; ISSN 0027-8424
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DNA
PHOTOCHEMISTRY
NUCLEOPROTEINS
RADIOSENSITIVITY EFFECTS
PYRIMIDINE DIMERS
RADIOINDUCTION
BACILLUS SUBTILIS
BACTERIAL SPORES
CLOSTRIDIUM
EXTREME ULTRAVIOLET RADIATION
BACILLUS
BACTERIA
CHEMISTRY
ELECTROMAGNETIC RADIATION
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PROTEINS
RADIATIONS
SPORES
ULTRAVIOLET RADIATION
550201* - Biochemistry- Tracer Techniques