The Bacillus subtilis HBsu protein modifies the effects of alpha/beta-type, small acid-soluble spore proteins on DNA.
HBsu, the Bacillus subtilis homolog of the Escherichia coli HU proteins and the major chromosomal protein in vegetative cells of B. subtilis, is present at similar levels in vegetative cells and spores ( approximately 5 x 10(4) monomers/genome). The level of HBsu in spores was unaffected by the presence or absence of the alpha/beta-type, small acid-soluble proteins (SASP), which are the major chromosomal proteins in spores. In developing forespores, HBsu colocalized with alpha/beta-type SASP on the nucleoid, suggesting that HBsu could modulate alpha/beta-type SASP-mediated properties of spore DNA. Indeed, in vitro studies showed that HBsu altered alpha/beta-type SASP protection of pUC19 from DNase digestion, induced negative DNA supercoiling opposing alpha/beta-type SASP-mediated positive supercoiling, and greatly ameliorated the alpha/beta-type SASP-mediated increase in DNA persistence length. However, HBsu did not significantly interfere with the alpha/beta-type SASP-mediated changes in the UV photochemistry of DNA that explain the heightened resistance of spores to UV radiation. These data strongly support a role for HBsu in modulating the effects of alpha/beta-type SASP on the properties of DNA in the developing and dormant spore.
Ross
M A
MA
Department of Biochemistry, University of Connecticut Health Center, Farmington, Connecticut 06032, USA.
Setlow
P
P
D001412:Bacillus subtilis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism / Q000502:physiology; D001426:Bacterial Proteins / Q000378:metabolism*; D004264:DNA Topoisomerases, Type I / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D004278:DNA, Superhelical / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism; D019281:Dimerization; D005455:Fluorescent Antibody Technique; D008970:Molecular Weight; D010777:Photochemistry; D010957:Plasmids / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D011740:Pyrimidine Dimers / Q000235:genetics / Q000378:metabolism / Q000528:radiation effects; D012808:Sigma Factor; D013171:Spores, Bacterial / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects; D014157:Transcription Factors; D014466:Ultraviolet Rays
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D004268:DNA-Binding Proteins; C075779:Hbsu protein, bacteria; D011740:Pyrimidine Dimers; D012808:Sigma Factor; D014157:Transcription Factors; C092468:spoIIR protein, Bacillus subtilis; C030069:spore-specific proteins, Bacillus; D003851:Deoxyribonucleases; D004264:DNA Topoisomerases, Type I