tailieunhanh - Báo cáo khoa học: Nuclear aggregates of polyamines are supramolecular structures that play a crucial role in genomic DNA protection and conformation

In a previous study we showed that natural polyamines interact in the nuclear environment with phosphate groups to form molecular aggregates [nuclear aggregates of polyamines (NAPs)] with estimated molecular mass values of 8000, 4800 and 1000 Da. NAPs were found to interact with genomic DNA, influence its conformation and interfere with the action of nucleases. | ềFEBS Journal Nuclear aggregates of polyamines are supramolecular structures that play a crucial role in genomic DNA protection and conformation Luciano D Agostino1 Massimiliano di Pietro1 and Aldo Di Luccia2 1 Department of Clinicaland ExperimentalMedicine Federico II University of Naples Italy 2 Department of AnimalProduction University of Bari Italy Keywords DNA conformation DNA protection molecular aggregates polyamines supra-molecular chemistry Correspondence L. D Agostino MD Facolta di Medicina Federico II Edificio-6 Via S. Pansini 5 80131 Naples Italy Fax 39 081746 2707 Tel 39 081746 2707 E-mail luciano@ Received 4 April2005 accepted 19 May 2005 doi In a previous study we showed that natural polyamines interact in the nuclear environment with phosphate groups to form molecular aggregates nuclear aggregates of polyamines NAPs with estimated molecular mass values of 8000 4800 and 1000 Da. NAPs were found to interact with genomic DNA influence its conformation and interfere with the action of nucleases. In the present work we demonstrated that NAPs protect naked genomic DNA from DNase I whereas natural polyamines spermine spermidine and putrescine fail to do so. In the context of DNA protection NAPs induced noticeable changes in DNA conformation which were revealed by temperature-dependent modifications of DNA electrophoretic properties. In addition we presented for NAPs a structural model of polyamine aggregation into macropolycyclic compounds. We believe that NAPs are the sole biological forms by which polyamines efficiently protect genomic DNA against DNase I while maintaining its dynamic structure. Polyamines interact with DNA phosphate groups by means of nonspecific electrostatic bonds 1 . This interaction has been shown to result in the protection of small DNA molecules from common damaging agents such as ionizing radiation and reactive oxygen species 2 3 . Polyamines in solution with polynucleotides have also been