Calcium binding to HMG1 protein induces DNA looping by the HMG-box domains.
Electron microscopy has shown that non-histone chromosomal HMG1 could induce DNA looping or compaction in the presence (but not in the absence) of Ca2+. The effect of calcium on DNA looping and compaction was interpreted as calcium binding to the acidic C-domain of HMG1. Both individual DNA-binding HMG1-box domains A and B were found to be involved in DNA looping and compaction. Treatment of HMG1 with a thiol-specific reagent, N-ethylmaleimide, inhibited the ability of the protein to induce DNA looping and compaction but not the electrostatic interaction with DNA. These results indicated that cysteine-sulfhydryl groups of the HMG1-box domains A and B are specifically involved in DNA looping and compaction, and that in the absence of calcium the acidic C-domain down-regulates these effects by modulation of the DNA-binding properties of the HMG1-box domains.
Stros
M
M
Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská, Brno.
Reich
J
J
Kolíbalová
A
A
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002417:Cattle; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D006609:High Mobility Group Proteins / Q000737:chemistry / Q000378:metabolism*; D008099:Liver / Q000737:chemistry; D008854:Microscopy, Electron; D009690:Nucleic Acid Conformation; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013950:Thymus Gland / Q000737:chemistry
D006609:High Mobility Group Proteins; D011994:Recombinant Proteins; D004247:DNA; D005033:Ethylmaleimide; D002118:Calcium