Binding of small, acid-soluble spore proteins to DNA plays a significant role in the resistance of Bacillus subtilis spores to hydrogen peroxide.
Dormant spores of Bacillus subtilis which lack the majority of the alpha/beta-type small, acid-soluble proteins (SASP) (termed alpha- beta- spores) that coat the DNA in wild-type spores are significantly more sensitive to hydrogen peroxide than are wild-type spores. Hydrogen peroxide treatment of alpha- beta- spores causes DNA strand breaks more readily than does comparable treatment of wild-type spores, and alpha- beta- spores, but not wild-type spores, which survive hydrogen peroxide treatment have acquired a significant number of mutations. The hydrogen peroxide resistance of wild-type spores appears to be acquired in at least two incremental steps during sporulation. The first increment is acquired at about the time of alpha/beta-type SASP synthesis, and the second increment is acquired approximately 2 h later, at about the time of dipicolinic acid accumulation. During sporulation of the alpha- beta- strain, only the second increment of hydrogen peroxide resistance is acquired. In contrast, sporulation mutants which accumulate alpha/beta-type SASP but progress no further in sporulation acquire only the first increment of hydrogen peroxide resistance. These findings strongly suggest that binding of alpha/beta-type SASP to DNA provides one increment of spore hydrogen peroxide resistance. Indeed, binding of alpha/beta-type SASP to DNA in vitro provides strong protection against cleavage of DNA by hydrogen peroxide.
Setlow
B
B
Department of Biochemistry, University of Connecticut Health Center, Farmington 06030-3305.
Setlow
P
P
D001412:Bacillus subtilis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D004269:DNA, Bacterial / Q000187:drug effects / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004352:Drug Resistance, Microbial; D006861:Hydrogen Peroxide / Q000494:pharmacology; D009154:Mutation; D012808:Sigma Factor; D013171:Spores, Bacterial / Q000187:drug effects / Q000378:metabolism; D014157:Transcription Factors
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C092468:spoIIR protein, Bacillus subtilis; C030069:spore-specific proteins, Bacillus; D006861:Hydrogen Peroxide