title: Localization of low-molecular-weight basic proteins in Bacillus megaterium spores by cross-linking with ultraviolet light.
abstract: Two low-molecular-weight basic proteins, termed A and B proteins, comprise about 15% of the protein of dormant spores of Bacillus megaterium. Irradiation of intact dormant spores with ultraviolet light results in covalent cross-linking of the A and B proteins to other spore macromolecules. The cross-linked A and B proteins are precipitated by ethanol and can be solubilized by treatment with deoxyribonuclease (75%) or ribonuclease (25%). Irradiation of complexes formed in vitro between deoxyribonucleic acid (DNA) or ribonucleic acid and a mixture of the low-molecular-weight basic proteins from spores also resulted in cross-linking of A and B proteins to nucleic acids. The dose-response curves for formation of covalent cross-links were similar for irradiation of both a protein-DNA complex in vitro and intact spores. However, if irradiation was carried out in vitro under conditions where DNA-protein complexes were disrupted, no covalent cross-links were formed. These data suggest that significant amounts of the low-molecular-weight basic proteins unique to bacterial spores are associated with spore DNA in vivo.
mesh_terms: D001410:Bacillus megaterium / Q000032:analysis*; D001426:Bacterial Proteins / Q000032:analysis*; D004269:DNA, Bacterial / Q000032:analysis*; D004307:Dose-Response Relationship, Radiation; D012329:RNA, Bacterial / Q000032:analysis; D013171:Spores, Bacterial / Q000032:analysis; D014466:Ultraviolet Rays
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012329:RNA, Bacterial