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Histone modifications influence the action of Snf2 family remodelling enzymes by different mechanisms.

Ferreira H, Flaus A, Owen-Hughes T - J. Mol. Biol. (2007)

Bottom Line: Specific patterns of histone acetylation are found to alter the rate of chromatin remodelling in different ways.In contrast, histone H4 tetra-acetylation was also found to reduce the activity of the Chd1 and Isw2 remodelling enzymes by reducing catalytic turnover without affecting recruitment.These observations illustrate a range of different means by which modifications to histones can influence the action of remodelling enzymes.

View Article: PubMed Central - PubMed

Affiliation: Division of Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.

ABSTRACT
Alteration of chromatin structure by chromatin modifying and remodelling activities is a key stage in the regulation of many nuclear processes. These activities are frequently interlinked, and many chromatin remodelling enzymes contain motifs that recognise modified histones. Here we adopt a peptide ligation strategy to generate specifically modified chromatin templates and used these to study the interaction of the Chd1, Isw2 and RSC remodelling complexes with differentially acetylated nucleosomes. Specific patterns of histone acetylation are found to alter the rate of chromatin remodelling in different ways. For example, histone H3 lysine 14 acetylation acts to increase recruitment of the RSC complex to nucleosomes. However, histone H4 tetra-acetylation alters the spectrum of remodelled products generated by increasing octamer transfer in trans. In contrast, histone H4 tetra-acetylation was also found to reduce the activity of the Chd1 and Isw2 remodelling enzymes by reducing catalytic turnover without affecting recruitment. These observations illustrate a range of different means by which modifications to histones can influence the action of remodelling enzymes.

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H4 tail regulates the catalytic activity of Isw2. (a) As Isw2 has been observed to move nucleosomes away from DNA ends, nucleosomes were assembled at a position close to a DNA end using the fragment 54A0. 3 fmol of Isw2 were incubated with 1pmol intact octamers assembled onto Cy3-labelled DNA and 1pmol octamers from which the first 19 amino acid residues of H4 had been deleted assembled on Cy5-labelled DNA for the times indicated at 30 °C in the presence of 1 mM ATP. gH4 nucleosomes were repositioned slower as shown in the graph. (b) In a similar comparison tetra-acetylated nucleosomes are repositioned slower than H4 V21C nucleosomes by Isw2. (c) Quantitative comparison of the effects of truncating and acetylating the H4 tail on Isw2 atpase activity. (d) Effects of H4 acetylation and truncation on the ATPase activity of Isw2. Reaction conditions are as for Figure 4 except using 0.2 nM Isw2 and different concentrations of 54W0 nucleosomes. Truncation of the H4 tail, and to a lesser extent histone acetylation, reduce the catalytic turnover of the enzyme without significantly affecting the Km.
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fig5: H4 tail regulates the catalytic activity of Isw2. (a) As Isw2 has been observed to move nucleosomes away from DNA ends, nucleosomes were assembled at a position close to a DNA end using the fragment 54A0. 3 fmol of Isw2 were incubated with 1pmol intact octamers assembled onto Cy3-labelled DNA and 1pmol octamers from which the first 19 amino acid residues of H4 had been deleted assembled on Cy5-labelled DNA for the times indicated at 30 °C in the presence of 1 mM ATP. gH4 nucleosomes were repositioned slower as shown in the graph. (b) In a similar comparison tetra-acetylated nucleosomes are repositioned slower than H4 V21C nucleosomes by Isw2. (c) Quantitative comparison of the effects of truncating and acetylating the H4 tail on Isw2 atpase activity. (d) Effects of H4 acetylation and truncation on the ATPase activity of Isw2. Reaction conditions are as for Figure 4 except using 0.2 nM Isw2 and different concentrations of 54W0 nucleosomes. Truncation of the H4 tail, and to a lesser extent histone acetylation, reduce the catalytic turnover of the enzyme without significantly affecting the Km.

Mentions: Subfamilies of Snf2 family chromatin remodelling proteins contain different motifs capable of interacting with histones raising the possibility that they may be regulated in different ways by histone modifications. One of the defining characteristics of the Iswi subfamily of remodelling enzymes is that they require a particular epitope within the H4 tail for efficient remodelling activity.33–36 One of the lysine residues adjacent to this motif, H4 K16, can be acetylated, and there is evidence that this reduces the activity of ISWI containing remodelling complexes.19,37 When we compared the relative rate of mobilisation of H4 tetra-acetylated nucleosomes relative to an unmodified control by the yeast Isw2 enzyme, we found that the rate is approximately 1.5-fold slower (Figure 5(b) and (c)). This reduction, whilst significant, is not as severe as deletion of the H4 tail (Figure 5(a) and (c)). However, its biological importance is underlined in studies on flies, where defects in the genetic interaction between H4 K16 acetylation and ISWI result in large scale chromosomal abnormalities.37


Histone modifications influence the action of Snf2 family remodelling enzymes by different mechanisms.

Ferreira H, Flaus A, Owen-Hughes T - J. Mol. Biol. (2007)

H4 tail regulates the catalytic activity of Isw2. (a) As Isw2 has been observed to move nucleosomes away from DNA ends, nucleosomes were assembled at a position close to a DNA end using the fragment 54A0. 3 fmol of Isw2 were incubated with 1pmol intact octamers assembled onto Cy3-labelled DNA and 1pmol octamers from which the first 19 amino acid residues of H4 had been deleted assembled on Cy5-labelled DNA for the times indicated at 30 °C in the presence of 1 mM ATP. gH4 nucleosomes were repositioned slower as shown in the graph. (b) In a similar comparison tetra-acetylated nucleosomes are repositioned slower than H4 V21C nucleosomes by Isw2. (c) Quantitative comparison of the effects of truncating and acetylating the H4 tail on Isw2 atpase activity. (d) Effects of H4 acetylation and truncation on the ATPase activity of Isw2. Reaction conditions are as for Figure 4 except using 0.2 nM Isw2 and different concentrations of 54W0 nucleosomes. Truncation of the H4 tail, and to a lesser extent histone acetylation, reduce the catalytic turnover of the enzyme without significantly affecting the Km.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC2279226&req=5

fig5: H4 tail regulates the catalytic activity of Isw2. (a) As Isw2 has been observed to move nucleosomes away from DNA ends, nucleosomes were assembled at a position close to a DNA end using the fragment 54A0. 3 fmol of Isw2 were incubated with 1pmol intact octamers assembled onto Cy3-labelled DNA and 1pmol octamers from which the first 19 amino acid residues of H4 had been deleted assembled on Cy5-labelled DNA for the times indicated at 30 °C in the presence of 1 mM ATP. gH4 nucleosomes were repositioned slower as shown in the graph. (b) In a similar comparison tetra-acetylated nucleosomes are repositioned slower than H4 V21C nucleosomes by Isw2. (c) Quantitative comparison of the effects of truncating and acetylating the H4 tail on Isw2 atpase activity. (d) Effects of H4 acetylation and truncation on the ATPase activity of Isw2. Reaction conditions are as for Figure 4 except using 0.2 nM Isw2 and different concentrations of 54W0 nucleosomes. Truncation of the H4 tail, and to a lesser extent histone acetylation, reduce the catalytic turnover of the enzyme without significantly affecting the Km.
Mentions: Subfamilies of Snf2 family chromatin remodelling proteins contain different motifs capable of interacting with histones raising the possibility that they may be regulated in different ways by histone modifications. One of the defining characteristics of the Iswi subfamily of remodelling enzymes is that they require a particular epitope within the H4 tail for efficient remodelling activity.33–36 One of the lysine residues adjacent to this motif, H4 K16, can be acetylated, and there is evidence that this reduces the activity of ISWI containing remodelling complexes.19,37 When we compared the relative rate of mobilisation of H4 tetra-acetylated nucleosomes relative to an unmodified control by the yeast Isw2 enzyme, we found that the rate is approximately 1.5-fold slower (Figure 5(b) and (c)). This reduction, whilst significant, is not as severe as deletion of the H4 tail (Figure 5(a) and (c)). However, its biological importance is underlined in studies on flies, where defects in the genetic interaction between H4 K16 acetylation and ISWI result in large scale chromosomal abnormalities.37

Bottom Line: Specific patterns of histone acetylation are found to alter the rate of chromatin remodelling in different ways.In contrast, histone H4 tetra-acetylation was also found to reduce the activity of the Chd1 and Isw2 remodelling enzymes by reducing catalytic turnover without affecting recruitment.These observations illustrate a range of different means by which modifications to histones can influence the action of remodelling enzymes.

View Article: PubMed Central - PubMed

Affiliation: Division of Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK.

ABSTRACT
Alteration of chromatin structure by chromatin modifying and remodelling activities is a key stage in the regulation of many nuclear processes. These activities are frequently interlinked, and many chromatin remodelling enzymes contain motifs that recognise modified histones. Here we adopt a peptide ligation strategy to generate specifically modified chromatin templates and used these to study the interaction of the Chd1, Isw2 and RSC remodelling complexes with differentially acetylated nucleosomes. Specific patterns of histone acetylation are found to alter the rate of chromatin remodelling in different ways. For example, histone H3 lysine 14 acetylation acts to increase recruitment of the RSC complex to nucleosomes. However, histone H4 tetra-acetylation alters the spectrum of remodelled products generated by increasing octamer transfer in trans. In contrast, histone H4 tetra-acetylation was also found to reduce the activity of the Chd1 and Isw2 remodelling enzymes by reducing catalytic turnover without affecting recruitment. These observations illustrate a range of different means by which modifications to histones can influence the action of remodelling enzymes.

Show MeSH