Self-association of the yeast nucleosome assembly protein 1.
The self-association properties of the yeast nucleosome assembly protein 1 (yNAP1) have been investigated using biochemical and biophysical methods. Protein cross-linking and calibrated gel filtration chromatography of yNAP1 indicate the protein exists as a complex mixture of species at physiologic ionic strength (75-150 mM). Sedimentation velocity reveals a distribution of species of 4.5-12 Svedbergs (S) over a 50-fold range of concentrations. The solution-state complexity is reduced at higher ionic strength, allowing for examination of the fundamental oligomer. Sedimentation equilibrium of a homogeneous 4.5 S population at 500 mM sodium chloride reveals these species to be yNAP1 dimers. These dimers self-associate to form higher order oligomers at more moderate ionic strength. Titration of guanidine hydrochloride converts the higher order oligomers to the homogeneous 4.5 S dimer and then converts the 4.5 S dimers to 2.5 S monomers. Circular dichroism shows that guanidine-mediated dissociation of higher order oligomers into yNAP1 dimers is accompanied by only slight changes in secondary structure. Dissociation of the dimer requires a nearly complete denaturation event.
Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870, USA.
Steven J
SJ
McBryant
Olve B
OB
Peersen
D018797:Cell Cycle Proteins; D002850:Chromatography, Gel; D002942:Circular Dichroism; D019281:Dimerization; D009687:Nuclear Proteins; D056490:Nucleosome Assembly Protein 1; D009994:Osmolar Concentration; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014461:Ultracentrifugation
D018797:Cell Cycle Proteins; C533556:NAP1 protein, S cerevisiae; D009687:Nuclear Proteins; D056490:Nucleosome Assembly Protein 1; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins