Binding of small acid-soluble spore proteins from Bacillus subtilis changes the conformation of DNA from B to A.
Small acid-soluble spore proteins (SASPs) appear 3-4 hr after the onset of sporulation in Gram-positive bacteria and constitute up to 20% of the protein of mature spores. Previous studies using Bacillus subtilis deletion mutants lacking SASP-alpha and -beta have shown that such mutations abolish the elevated resistance of spores to UV radiation. Analyses using circular dichroism and Fourier-transform infrared spectroscopy now demonstrate that binding alpha/beta-type SASPs to DNA in vitro causes a structural change in DNA, from the B to the A conformation. This may provide the basis whereby alpha/beta-type SASPs confer increased spore UV resistance in vivo--by changing spore DNA conformation, they alter DNA photochemistry such that UV irradiation produces spore photoproduct instead of the more lethal cyclobutane-type thymine dimers.
Mohr
S C
SC
Department of Chemistry, Boston University, MA 02215.
Sokolov
N V
NV
He
C M
CM
Setlow
P
P
D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D002942:Circular Dichroism; D004247:DNA / Q000378:metabolism* / Q000648:ultrastructure; D005583:Fourier Analysis; D007700:Kinetics; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D012808:Sigma Factor; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D013171:Spores, Bacterial / Q000378:metabolism; D014157:Transcription Factors
D001426:Bacterial Proteins; D012808:Sigma Factor; D014157:Transcription Factors; C092468:spoIIR protein, Bacillus subtilis; C030069:spore-specific proteins, Bacillus; D004247:DNA