Cloning of a cDNA for DNA supercoiling factor reveals a distinctive Ca(2+)-binding protein.
DNA supercoiling factor is a protein capable of generating negative supercoils into a relaxed DNA in conjunction with eukaryotic DNA topoisomerase II. A cDNA clone encoding the Bombyx mori supercoiling factor has been isolated and characterized. The cDNA sequence contains an open reading frame of 322 amino acids rich in acidic residues. A local region of the predicted polypeptide shares a weak homology with the central portion of bacterial DNA gyrase A subunit. The cDNA sequence also predicts two direct repeats within the factor. Each repeat unit consists of a potential EF-hand domain. The factor contains three other potential EF-hand domains and actually binds Ca2+. Moreover, the supercoiling reaction has been shown to be activated by Ca2+. These results implicate Ca2+ in the control of the superhelical state of DNA.
Ohta
T
T
Department of Developmental Genetics, National Institute of Genetics, Graduate University for Advanced Studies, Mishima, Japan.
Kobayashi
M
M
Hirose
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000737:chemistry*; D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D003001:Cloning, Molecular; D004250:DNA Topoisomerases, Type II / Q000737:chemistry; D004278:DNA, Superhelical / Q000737:chemistry; D029721:Drosophila Proteins; D008969:Molecular Sequence Data; D009687:Nuclear Proteins
D002135:Calcium-Binding Proteins; C115373:DNA supercoiling factor, Drosophila; D004278:DNA, Superhelical; D029721:Drosophila Proteins; D009687:Nuclear Proteins; D004250:DNA Topoisomerases, Type II; D002118:Calcium