Two new photoaffinity polyamines appear to alter the helical twist of DNA in nucleosome core particles.
Two new photoaffinity derivatives of polyamines have been synthesized by the reaction of spermine or spermidine with methyl 4-azidobenzimidate. The new compounds were purified chromatographically and characterized by several methods including proton magnetic resonance spectroscopy. The spermine derivative is N1-ABA-spermine [(azidobenzamidino)spermine], and the spermidine derivative is a mixture of N1- and N8-ABA-spermidine. ABA-spermine stabilizes nucleosome core particles in thermal denaturation experiments, with similar but not identical effects when compared with the parent polyamine, spermine. In circular dichroism experiments, ABA-spermine was capable of producing a B----Z transition in poly(dG-m5dC) at a concentration of 30 microM, compared with 5 microM required to produce the same effect with spermine. On the other hand, ANB-spermine [(azidonitrobenzoyl)spermine; Morgan, J. E., Calkins, C. C., & Matthews, H. R. (1989) Biochemistry 28, 5095-5106] stabilized the B form of poly(dG-br5dC). ABA-spermine is a potent inhibitor of ornithine decarboxylase from Escherichia coli, giving 50% inhibition at 0.12 mM, while ANB-spermine is a modest inhibitor, comparable to spermine or spermidine. Under conditions of nitrogen-limited growth, yeast take up ABA-spermine and ABA-spermidine at approximately one-third to half the rate of spermidine or spermine. In contrast, ANB-spermine was not significantly taken up. The photoaffinity polyamines were used to photoaffinity label the DNA in nucleosome core particles, and the sites of labeling were determined by exonuclease protection. All photoaffinity reagents showed both nonspecific labeling and specific sites of higher occupancy. However, the positions of the sites varied: the ANB-spermine sites confirmed those previously reported (Morgan et al., 1989); the ABA-spermine and ABA-spermidine sites were spaced at 9.8 bp intervals from the 3' end of each DNA strand. This observation, together with the effect of spermine on the circular dichroism of DNA in nucleosome core particles, implies that polyamines alter the helical twist of DNA in nucleosome core particles. The ABA-polyamines are offered as general-purpose photoaffinity polyamine reagents.
Clark
E
E
Department of Biological Chemistry, University of California, Davis 95616.
Swank
R A
RA
Morgan
J E
JE
Basu
H
H
Matthews
H R
HR
D000345:Affinity Labels / Q000494:pharmacology*; D000818:Animals; D001386:Azides / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology*; D001665:Binding Sites; D002417:Cattle; D004247:DNA / Q000187:drug effects* / Q000648:ultrastructure; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D009690:Nucleic Acid Conformation; D009707:Nucleosomes / Q000187:drug effects / Q000502:physiology*; D009955:Ornithine Decarboxylase / Q000378:metabolism; D011073:Polyamines / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013095:Spermidine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D013096:Spermine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D013950:Thymus Gland / Q000502:physiology
D000345:Affinity Labels; D001386:Azides; D007202:Indicators and Reagents; D009707:Nucleosomes; D011073:Polyamines; C068638:N(1)-(azidobenzamidino)spermine; D013096:Spermine; D004247:DNA; D009955:Ornithine Decarboxylase; D013095:Spermidine