title: DNA chain unwinding and annealing reactions of lipocortin (annexin) I heterotetramer: regulation by Ca(2+) and Mg(2+).
abstract: Lipocortin I-S100 (calcyclin) heterotetramer exhibited ATPase activity in the presence of dsDNA but not ssDNA. To demonstrate its helicase activity, an 80-mer polynucleotide complementary to the replication origin of M13mp18 was synthesized, and the oligonucleotide, (dC)(20), was ligated to either its 5'- or 3'- end for binding to lipocortin. Lipocortin I heterotetramer displaced chains of the partially Y-shaped duplexes with a dC-tail at either the 5'- or 3'- end. The chain displacement required ATP and Mg(2+). Nonhydrolyzable ATP analogues were not effective. Lipocortin I heterotetramer also catalyzed annealing of the polynucleotides to M13mp18. Ca(2+) and phospholipids but not ATP and Mg(2+) were essential for this reaction. Since the chain displacing and annealing reactions were inhibited by monospecific anti-lipocortin I or anti-S100 antibodies, the present observations suggest that the lipocortin I heterotetramer regulates unwinding and annealing of DNA by Mg(2+) (plus ATP) and Ca(2+) (and phospholipids), respectively.
authors.affiliation: Department of Pharmaceutical Sciences, Wayne State University, Detroit, Michigan 48202, USA.
authors.forename: Aiko
authors.initials: A
authors.lastname: Hirata
authors.forename: Fusao
authors.initials: F
authors.lastname: Hirata
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D017305:Annexin A1 / Q000378:metabolism; D002118:Calcium / Q000494:pharmacology*; D004247:DNA / Q000378:metabolism*; D004265:DNA Helicases / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D008274:Magnesium / Q000494:pharmacology*; D009693:Nucleic Acid Hybridization; D010743:Phospholipids / Q000494:pharmacology; D009418:S100 Proteins / Q000378:metabolism*
chemical_list: D017305:Annexin A1; D010743:Phospholipids; D009418:S100 Proteins; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; D004265:DNA Helicases; D008274:Magnesium; D002118:Calcium