[Interaction of eukaryotic DNA with apolipoprotein A-I and its complexes with glucocorticoids].
A biochemically active complex of apolipoprotein A-I with tetrahydrocortisol was revealed, which increases gene expression in hepatocytes. It was shown by the method of fluorescent probe that titration of rat liver DNA by the apolipoprotein A-I-tetrahydrocortisol complex leads to the appearance of single-stranded fragments. The effect of the complex on the secondary structure of native DNA was confirmed by the method of small-angle X-ray scattering. It was shown that approximately 54 apolipoprotein A-I molecules carrying tetrahydrocortisol as a ligand bind to one molecule of isolated native DNA, inducing a break of hydrogen bonds between the pair of nitrous bases. It is concluded that the cooperative effect of high-density lipoproteins and cortisol in the regulation of gene expression in hepatocytes with the participation of resident liver macrophages is accomplished by a new biochemical mechanism. This mechanism makes itself evident as a result of the interaction of DNA with the apolipoprotein A-I-tetrahydrocortisol complex, the appearance of single-stranded DNA regions in binding sites, and subsequent initiation of gene transcription.
Panin
L E
LE
Institute of Biochemistry, Siberian Division, Russian Academy of Medical Sciences, Novosibirsk, Russia.
Tuzikov
F V
FV
Tuzikova
N A
NA
Gimautdinova
O I
OI
Poliakov
L M
LM
D000818:Animals; D016632:Apolipoprotein A-I / Q000737:chemistry / Q000378:metabolism*; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D005260:Female; D006860:Hydrogen Bonding; D008099:Liver / Q000166:cytology / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D012542:Scattering, Radiation; D013760:Tetrahydrocortisol / Q000737:chemistry / Q000378:metabolism*
D016632:Apolipoprotein A-I; D013760:Tetrahydrocortisol; D004247:DNA