Andrews AJ , Downing G , Brown K , Park YJ , Luger K .

GM067777 NIGMS NIH HHS , R01 GM067777-06 NIGMS NIH HHS , Howard Hughes Medical Institute , R01 GM067777 NIGMS NIH HHS , HHMI_LUGER_K Howard Hughes Medical Institute

	FIGURE 1. Fluorescence change as a function of protein binding. A, fluorescence (A.U.) as a function of wavelength (nm), with closed circles/squares representing the signal from the excitation of Alexa-488 (yNap1m*) in the presence (closed squares) or absence (closed circles) of H2A/H2B and the open circles/squares representing Alexa-546 (H2A/H2B(T112C)) in the presence (open squares) or absence (open circles) of yNap1. B, normalized fluorescence change as a function of either H2A/H2B titrated into Alexa-546-labeled yNap1 (closed squares) or yNap1 titrated into Alexa-546 labeled H2A/H2B (open circles). C, change in fluorescence plotted as a function of the ratio of H2A/H2B to yNap1. The intersection of the linear phase with the plateau is equal to the molar ratio at which yNap1 is saturated. These data suggest that two H2A/H2B dimers bind one yNap1 dimer or that one H2A/H2B binds one yNap1 monomer. The conditions were 20–50 mm Tris, pH 7.5, 1 mm dithiothreitol, 0.1 mg/ml bovine serum albumin, 90–120 mm NaCl, (1–5) × 10–10 m Alexa-labeled protein, and (0–5) × 10–7 m non-labeled protein. For results of the fit see Table 1.
	FIGURE 2. Affinity and stoichiometry of the yNap1-H2A/H2B dimer complex. Normalized change in fluorescence as a function of yNap1 (open circles), yNap1(74–417) (open squares), yNap1(1–365) (closed triangles), and yNap1(74–365) (closed circles), all as monomers. The conditions were 20–50 mm Tris, pH 7.5, 1 mm dithiothreitol, 0.1 mg/ml bovine serum albumin, 90–120 mm NaCl, (0.5–1) × 10–10 m Alexa-488-H2A/H2B(T112C), and (0–5 × 10–7 m yNap1 or its truncations. For results of the fit see Table 1.
	FIGURE 3. Cooperativity is dependent on both the ionic strength and histone tails. A, Hill plot of H2A/H2B binding yNap1 at ∼0.15 m (closed circles) and ∼0.35 m (open squares-same data in all plots) ionic strength. The slopes of these data result in a nH of 1 ± 0.1 and 2.4 ± 0.2, respectively. B, normalized fluorescence change as a function of histone dimer. Closed circles are tail-less dimers, and open squares are major type histone dimer. Inset of B is the Hill plot of the tail-less (closed circles) and major type (open squares) dimer. The slopes of these data result in an nH of 1.5 ± 0.1 and 1.0 ± 0.1, respectively.
	FIGURE 4. The interaction of yNap1 and DNA with histone tetramer. A, normalized fluorescence change as a function of histone tetramer binding to (yNap1m*)-Alexa-546 (closed circles), tail-less (H3/H4)2 (open squares), and H3(H113A)/H4 (plotted as tetramer) (open squares). Inset of A is the stoichiometry of (H3/H4)2 to yNAP dimer. (H3/H4)2 was titrated against 1×10–7 m (yNap1m*)-Alexa-546 to result in a stoichiometry of 1 histone tetramer to 1 yNap1 dimer. B, normalized fluorescence change as a function of DNA binding to (H3/H4(E63C))2-Alexa-488 (10–10 m). Buffer conditions were 20–50 mm Tris, pH 7.5, 1 mm dithiothreitol, 0.1 mg/ml bovine serum albumin, and 300 mm NaCl.
	FIGURE 5. Binding and stoichiometry of H1 to yNap1. The normalized fluorescence change as a function of linker histone H1 binding to (yNap1m*)-Alexa-546. Inset is the stoichiometry of H1 to yNap1. While two phases were easily discernible the second did not level out as expected. These data suggest specific binding of two H1 linker histones to yNap1 and a possible third nonspecific H1-yNap1 interaction.

Banks, Folding mechanism of the (H3-H4)2 histone tetramer of the core nucleosome. 2004, Pubmed

Banks, Folding mechanism of the (H3-H4)2 histone tetramer of the core nucleosome. 2004, Pubmed
De Koning, Histone chaperones: an escort network regulating histone traffic. 2007, Pubmed
Dyer, Reconstitution of nucleosome core particles from recombinant histones and DNA. 2004, Pubmed
Eitoku, Histone chaperones: 30 years from isolation to elucidation of the mechanisms of nucleosome assembly and disassembly. 2008, Pubmed
Galichet, Developmentally controlled farnesylation modulates AtNAP1;1 function in cell proliferation and cell expansion during Arabidopsis leaf development. 2006, Pubmed
Karantza, Thermodynamic studies of the core histones: ionic strength and pH dependence of H2A-H2B dimer stability. 1995, Pubmed
Karantza, Thermodynamic studies of the core histones: pH and ionic strength effects on the stability of the (H3-H4)/(H3-H4)2 system. 1996, Pubmed
Kepert, NAP1 modulates binding of linker histone H1 to chromatin and induces an extended chromatin fiber conformation. 2005, Pubmed
Luger, Crystal structure of the nucleosome core particle at 2.8 A resolution. 1997, Pubmed
Luger, Expression and purification of recombinant histones and nucleosome reconstitution. 1999, Pubmed
Mazurkiewicz, On the mechanism of nucleosome assembly by histone chaperone NAP1. 2006, Pubmed
McBryant, Preferential binding of the histone (H3-H4)2 tetramer by NAP1 is mediated by the amino-terminal histone tails. 2003, Pubmed , Xenbase
McBryant, Self-association of the yeast nucleosome assembly protein 1. 2004, Pubmed
Nakagawa, Multistep chromatin assembly on supercoiled plasmid DNA by nucleosome assembly protein-1 and ATP-utilizing chromatin assembly and remodeling factor. 2001, Pubmed
Park, The structure of nucleosome assembly protein 1. 2006, Pubmed
Park, Structure and function of nucleosome assembly proteins. 2006, Pubmed
Park, A new fluorescence resonance energy transfer approach demonstrates that the histone variant H2AZ stabilizes the histone octamer within the nucleosome. 2004, Pubmed , Xenbase
Park, A beta-hairpin comprising the nuclear localization sequence sustains the self-associated states of nucleosome assembly protein 1. 2008, Pubmed
Park, Nucleosome assembly protein 1 exchanges histone H2A-H2B dimers and assists nucleosome sliding. 2005, Pubmed
Sharma, The coactivators CBP/p300 and the histone chaperone NAP1 promote transcription-independent nucleosome eviction at the HTLV-1 promoter. 2008, Pubmed
Starich, NMR structure of HMfB from the hyperthermophile, Methanothermus fervidus, confirms that this archaeal protein is a histone. 1996, Pubmed
Tóth, Association states of nucleosome assembly protein 1 and its complexes with histones. 2005, Pubmed
Varga-Weisz, Binding of histones H1 and H5 and their globular domains to four-way junction DNA. 1994, Pubmed
Varga-Weisz, Competition between linker histones and HMG1 for binding to four-way junction DNA: implications for transcription. 1994, Pubmed
Zlatanova, Nap1: taking a closer look at a juggler protein of extraordinary skills. 2007, Pubmed , Xenbase