Resistance of spores of Bacillus species to ultraviolet light.
Dormant spores of the various Bacillus species, including B. subtilis, are 5 to 50 times more resistant to UV radiation than are the corresponding growing cells. This elevated spore UV resistance is due to: a) the photochemistry of DNA within spores, as UV generates few if any cyclobutane dimers, but rather a photoproduct (Fig. 1) called spore photoproduct (SP; 5-thyminyl-5,6-dihydrothymine); and b) DNA repair, in particular SP-specific repair, during spore germination. The novel UV photochemistry of spore DNA is largely due to its saturation with a group of small, acid-soluble proteins (SASP), which are unique to spores and whose binding alters the DNA conformation and thus its photochemistry. SP-specific repair is also unique to spores and is carried out by a light-independent SP-lyase, an iron-sulfur protein that utilizes S-adenosylmethionine to catalyze SP monomerization without DNA backbone cleavage.
Setlow
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Department of Biochemistry, University of Connecticut Health Center, Farmington, Connecticut 06032, USA. setlow@sun.uchc.edu
D000595:Amino Acid Sequence; D001407:Bacillus / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects*; D004260:DNA Repair; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics* / Q000528:radiation effects*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011740:Pyrimidine Dimers; D011836:Radiation Tolerance; D013171:Spores, Bacterial / Q000235:genetics / Q000528:radiation effects; D013941:Thymine / Q000031:analogs & derivatives*; D014466:Ultraviolet Rays
D004269:DNA, Bacterial; D011740:Pyrimidine Dimers; C009484:5-thyminyl-5,6-dihydrothymine; D013941:Thymine