title: Self-association of linker histone H5 and of its globular domain: evidence for specific self-contacts.
abstract: The ability of avian-specific linker histone H5, and the globular domains of H5 (GH5) and H1(0) (GH1(0), to self-associate either free in solution or when bound to DNA was investigated. All three proteins underwent a salt-dependent increase in turbidity that may be indicative of nonspecific interactions. Dithiobis(succinimidyl propionate) cross-linking was used to measure specific contacts for both H5 and GH5 free in solution and bound to DNA. H5 and GH5 each became cross-linked in solution, with GH5 displaying divalent polymerization interactions, which suggests that two specific surfaces were involved in the assembly process. For GH5-DNA complexes, cross-linking appeared to be largely the consequence of aggregation, but under low concentrations of DSP, cross-linking GH5 was observed to assemble preferentially onto DNA before oligomerizing to form massive aggregates. Both linear and supercoiled DNA facilitated GH5 interactions compared to assembly in solution; differences in the distribution of cross-linked polymer sizes indicates that assembly is dependent on both the presence of DNA and the morphology of the DNA. Finally, on the basis of a technique referred to as quantitative proteolysis, GH5 assembly on DNA appears to involve specific protein-protein contacts involving the C terminus of one partner. Overall, the cumulative results reported here support the premise that linker histones assemble specifically both in solution and on DNA.
authors.affiliation: Department of Biochemistry and Biophysics, Oregon State University, Corvallis 97331-7305, USA.
authors.forename: G J
authors.initials: GJ
authors.lastname: Carter
authors.forename: K
authors.initials: K
authors.lastname: van Holde
mesh_terms: D000818:Animals; D002645:Chickens; D002918:Chymotrypsin; D002942:Circular Dichroism; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D006657:Histones / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D008958:Models, Molecular; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012965:Sodium Chloride; D012996:Solutions; D013388:Succinimides; D014961:X-Ray Diffraction
chemical_list: D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D006657:Histones; D009841:Oligonucleotides; D012996:Solutions; D013388:Succinimides; D012965:Sodium Chloride; C035759:3,3'-dithiobis(sulfosuccinimidyl propionate); D002918:Chymotrypsin