title: Biophysical characterization of the DNA binding and condensing properties of adenoviral core peptide mu.
abstract: Cationic peptides containing Lys and Arg residues interact with DNA via charge-charge interactions and are known to play an important role in DNA charge neutralization and condensation processes. In this paper, we describe investigations of the interaction of the cationic adenovirus core complex peptide mu with a dodecameric ODN (12 bp) and pDNA (7528 bp) using a combination of fluorescence spectroscopy, circular dichroism spectroscopy, isothermal titration calorimetry, and photon correlation spectroscopy. Comparisons are made with protamine, a cationic peptide well-known for DNA charge neutralization and condensation. Equilibrium dissociation constants are derived independently by both CD and ITC methods for the interaction between protamine or mu with pDNA (K(d) = 0.6-1 microM). Thermodynamic data are also obtained by ITC, indicating strong charge-charge interactions. The interaction of protamine with pDNA takes place with decreasing entropy (-28.7 cal mol(-1) K(-1)); unusually, the interaction of mu with pDNA takes place with increasing entropy (Delta S degrees (bind) = 11.3 cal mol(-1) K(-1)). Although protamine and mu appear to destabilize pDNA double helix character to similar extents, according to CD thermal titration analyses, PCS studies show that interactions between mu and pDNA result in the formation of significantly more size-stable condensed particles than protamine. The enhanced flexibility and size stability of mu-DNA (MD) particles (80-110 nm) compared to protamine counterparts suggest that MD particles are ideal for use as a part of new nonviral gene delivery vectors.
authors.affiliation: Department of Chemistry, Imperial College Genetic Therapies Centre, Flowers Building, Armstrong Road, South Kensington, London SW7 2AZ, UK. mike.keller@ic.ac.uk
authors.forename: Michael
authors.initials: M
authors.lastname: Keller
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Tagawa
authors.forename: Monika
authors.initials: M
authors.lastname: Preuss
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Miller
mesh_terms: D000256:Adenoviridae / Q000378:metabolism*; D002151:Calorimetry; D002412:Cations; D002942:Circular Dichroism; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D019277:Entropy; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors; D007700:Kinetics; D009841:Oligonucleotides / Q000378:metabolism; D010455:Peptides / Q000737:chemistry*; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D014758:Viral Core Proteins / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D002412:Cations; D004268:DNA-Binding Proteins; D009841:Oligonucleotides; D010455:Peptides; D014758:Viral Core Proteins; C061289:virion protein mu, adenovirus; D004247:DNA