Data di Pubblicazione:
2005
Citazione:
Positively charged surfaces increase the flexibility of DNA / A. Podestà, M. Indrieri, D.C. Brogioli, G.S. Manning, P. Milani, R. Guerra, L. Finzi, D. Dunlap. - In: BIOPHYSICAL JOURNAL. - ISSN 0006-3495. - 89:4(2005), pp. 2558-2563. [10.1529/biophysj.105.064667]
Abstract:
Many proteins ‘‘bind’’ DNA through positively charged amino acids on their surfaces. However, to overcome
significant energetic and topological obstacles, proteins that bend or package DNA might also modulate the stiffness that is
generated by repulsions between phosphates within DNA. Much previous work describes how ions change the flexibility of DNA
in solution, but when considering macromolecules such as chromatin in which the DNA contacts the nucleosome core each turn
of the double helix, it may be more appropriate to assess the flexibility of DNA on charged surfaces. Mica coated with positively
charged molecules is a convenient substrate upon which the flexibility of DNA may be directly measured with a scanning force
microscope. In the experiments described below, the flexibility of DNA increased as much as fivefold depending on the
concentration and type of polyamine used to coat mica. Using theory that relates charge neutralization to flexibility, we predict
that phosphate repulsions were attenuated by ;50% in the most flexible DNA observed. This simple method is an important
tool for investigating the physiochemical causes and molecular biological effects of DNA flexibility, which affects DNA
biochemistry ranging from chromatin stability to viral encapsulation.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
atomic force microscopy ; biochemistry ; biomechanics ; DNA ; molecular biophysics
Elenco autori:
A. Podestà, M. Indrieri, D.C. Brogioli, G.S. Manning, P. Milani, R. Guerra, L. Finzi, D. Dunlap
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