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. 1999 Jan 15;442(2-3):189-92.
doi: 10.1016/s0014-5793(98)01649-4.

Transition protein 4 from boar late spermatid nuclei is a topological factor that stimulates DNA-relaxing activity of topoisomerase I

K Akama  1 , M Kondo, H Sato, M Nakano
Affiliations

Transition protein 4 from boar late spermatid nuclei is a topological factor that stimulates DNA-relaxing activity of topoisomerase I

K Akama et al. FEBS Lett. .

Abstract

Transition protein 4 (TP4) from boar late spermatid nuclei, having higher affinity for double-stranded DNA and a local melting activity of DNA, stimulated SV40 DNA-relaxing activity of eukaryotic topoisomerase I at TP4/DNA molar ratios of 6.6-11. A TP4-spermidine mixture stimulated the activity of topoisomerase I much more than spermidine alone, but no more than TP4 alone, and poly-L-arginine did not. These results suggest that TP4 contributes to the chromatin reorganization in the late spermatid nuclei from nucleosomal-type structure with negatively supercoiled DNA to nucleoprotamine structure with no supercoiled DNA.

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