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The plasticity of WDR5 peptide-binding cleft enables the binding of the SET1 family of histone methyltransferases.

Zhang P, Lee H, Brunzelle JS, Couture JF - Nucleic Acids Res. (2012)

Bottom Line: We herein provide biochemical and structural evidence showing that WDR5 binds the Win motifs of MLL2-4, SET1A and SET1B.Comparative analysis of WDR5-Win complexes reveals that binding of the Win motifs is achieved by the plasticity of WDR5 peptidyl-arginine-binding cleft allowing the C-terminal ends of the Win motifs to be maintained in structurally divergent conformations.Overall, our findings illustrate the function of WDR5 in scaffolding the SET1 family of KMTs and further emphasize on the important role of WDR5 in regulating global histone H3 Lys-4 methylation.

View Article: PubMed Central - PubMed

Affiliation: Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada.

ABSTRACT
In mammals, the SET1 family of lysine methyltransferases (KMTs), which includes MLL1-5, SET1A and SET1B, catalyzes the methylation of lysine-4 (Lys-4) on histone H3. Recent reports have demonstrated that a three-subunit complex composed of WD-repeat protein-5 (WDR5), retinoblastoma-binding protein-5 (RbBP5) and absent, small, homeotic disks-2-like (ASH2L) stimulates the methyltransferase activity of MLL1. On the basis of studies showing that this stimulation is in part controlled by an interaction between WDR5 and a small region located in close proximity of the MLL1 catalytic domain [referred to as the WDR5-interacting motif (Win)], it has been suggested that WDR5 might play an analogous role in scaffolding the other SET1 complexes. We herein provide biochemical and structural evidence showing that WDR5 binds the Win motifs of MLL2-4, SET1A and SET1B. Comparative analysis of WDR5-Win complexes reveals that binding of the Win motifs is achieved by the plasticity of WDR5 peptidyl-arginine-binding cleft allowing the C-terminal ends of the Win motifs to be maintained in structurally divergent conformations. Consistently, enzymatic assays reveal that WDR5 plays an important role in the optimal stimulation of MLL2-4, SET1A and SET1B methyltransferase activity by the RbBP5-ASH2L heterodimer. Overall, our findings illustrate the function of WDR5 in scaffolding the SET1 family of KMTs and further emphasize on the important role of WDR5 in regulating global histone H3 Lys-4 methylation.

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Stimulation of the SET1 family of KMTs activity on histone H3 by the core complex. Radiometric methyltransferase assays performed with MLL2 (A), MLL3 (B), MLL4 (C), SET1A (D) and SET1B (E) either in the absence or presence of WDR5 and the RbBP5–ASH2L complex. Methyltransferase assays were performed at a concentration of enzyme in the linear range of activity of MLL2 (1 µM), MLL3 (0.5 µM), MLL4 (1 µM), SET1A (1 µM) and SET1B (0.5 µM) complexes. Activity is represented as the average of three independent experiments performed in triplicate. Error bars indicate the standard deviation between the assays.
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gkr1235-F4: Stimulation of the SET1 family of KMTs activity on histone H3 by the core complex. Radiometric methyltransferase assays performed with MLL2 (A), MLL3 (B), MLL4 (C), SET1A (D) and SET1B (E) either in the absence or presence of WDR5 and the RbBP5–ASH2L complex. Methyltransferase assays were performed at a concentration of enzyme in the linear range of activity of MLL2 (1 µM), MLL3 (0.5 µM), MLL4 (1 µM), SET1A (1 µM) and SET1B (0.5 µM) complexes. Activity is represented as the average of three independent experiments performed in triplicate. Error bars indicate the standard deviation between the assays.

Mentions: The Win motif of MLL1 is important for its interaction with the WDR5–RbBP5–ASH2L complex and thereby stimulation of its methyltransferase activity (23). After showing that WDR5 binds the Win motifs of MLL1-4 and SET1A/B, we examined the role of the WDR5–RbBP5–ASH2L complex in stimulating the other members of the SET1 family of methyltransferases. A comparison of SET1 KMT activity in the absence or presence of the WDR5–RbBP5–ASH2L complex confirmed that the core complex enhances the methyltransferase activity of all members, with the exception of MLL5, but with differences in the fold of stimulation. Specifically, the WDR5–RbBP5–ASH2L complex stimulated MLL2/MLL3 and MLL4 activity by ∼52/256- and ∼15-fold, respectively, while co-incubation of SET1A and SET1B with the core complex subunits increased methylation of histone H3 by ∼40- and ∼1290-fold (Figure 4). The stimulatory roles of the core complex on SET1B can be rationalized by the nearly undetectable activity of these KMTases on histone H3 in the absence of the WDR5–RbBP5–ASH2L complex. Overall, these observations support initial in vivo data showing that the members of the core complex are critical for global levels of histone H3K4 methylation.Figure 4.


The plasticity of WDR5 peptide-binding cleft enables the binding of the SET1 family of histone methyltransferases.

Zhang P, Lee H, Brunzelle JS, Couture JF - Nucleic Acids Res. (2012)

Stimulation of the SET1 family of KMTs activity on histone H3 by the core complex. Radiometric methyltransferase assays performed with MLL2 (A), MLL3 (B), MLL4 (C), SET1A (D) and SET1B (E) either in the absence or presence of WDR5 and the RbBP5–ASH2L complex. Methyltransferase assays were performed at a concentration of enzyme in the linear range of activity of MLL2 (1 µM), MLL3 (0.5 µM), MLL4 (1 µM), SET1A (1 µM) and SET1B (0.5 µM) complexes. Activity is represented as the average of three independent experiments performed in triplicate. Error bars indicate the standard deviation between the assays.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3351189&req=5

gkr1235-F4: Stimulation of the SET1 family of KMTs activity on histone H3 by the core complex. Radiometric methyltransferase assays performed with MLL2 (A), MLL3 (B), MLL4 (C), SET1A (D) and SET1B (E) either in the absence or presence of WDR5 and the RbBP5–ASH2L complex. Methyltransferase assays were performed at a concentration of enzyme in the linear range of activity of MLL2 (1 µM), MLL3 (0.5 µM), MLL4 (1 µM), SET1A (1 µM) and SET1B (0.5 µM) complexes. Activity is represented as the average of three independent experiments performed in triplicate. Error bars indicate the standard deviation between the assays.
Mentions: The Win motif of MLL1 is important for its interaction with the WDR5–RbBP5–ASH2L complex and thereby stimulation of its methyltransferase activity (23). After showing that WDR5 binds the Win motifs of MLL1-4 and SET1A/B, we examined the role of the WDR5–RbBP5–ASH2L complex in stimulating the other members of the SET1 family of methyltransferases. A comparison of SET1 KMT activity in the absence or presence of the WDR5–RbBP5–ASH2L complex confirmed that the core complex enhances the methyltransferase activity of all members, with the exception of MLL5, but with differences in the fold of stimulation. Specifically, the WDR5–RbBP5–ASH2L complex stimulated MLL2/MLL3 and MLL4 activity by ∼52/256- and ∼15-fold, respectively, while co-incubation of SET1A and SET1B with the core complex subunits increased methylation of histone H3 by ∼40- and ∼1290-fold (Figure 4). The stimulatory roles of the core complex on SET1B can be rationalized by the nearly undetectable activity of these KMTases on histone H3 in the absence of the WDR5–RbBP5–ASH2L complex. Overall, these observations support initial in vivo data showing that the members of the core complex are critical for global levels of histone H3K4 methylation.Figure 4.

Bottom Line: We herein provide biochemical and structural evidence showing that WDR5 binds the Win motifs of MLL2-4, SET1A and SET1B.Comparative analysis of WDR5-Win complexes reveals that binding of the Win motifs is achieved by the plasticity of WDR5 peptidyl-arginine-binding cleft allowing the C-terminal ends of the Win motifs to be maintained in structurally divergent conformations.Overall, our findings illustrate the function of WDR5 in scaffolding the SET1 family of KMTs and further emphasize on the important role of WDR5 in regulating global histone H3 Lys-4 methylation.

View Article: PubMed Central - PubMed

Affiliation: Ottawa Institute of Systems Biology, Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, ON, Canada.

ABSTRACT
In mammals, the SET1 family of lysine methyltransferases (KMTs), which includes MLL1-5, SET1A and SET1B, catalyzes the methylation of lysine-4 (Lys-4) on histone H3. Recent reports have demonstrated that a three-subunit complex composed of WD-repeat protein-5 (WDR5), retinoblastoma-binding protein-5 (RbBP5) and absent, small, homeotic disks-2-like (ASH2L) stimulates the methyltransferase activity of MLL1. On the basis of studies showing that this stimulation is in part controlled by an interaction between WDR5 and a small region located in close proximity of the MLL1 catalytic domain [referred to as the WDR5-interacting motif (Win)], it has been suggested that WDR5 might play an analogous role in scaffolding the other SET1 complexes. We herein provide biochemical and structural evidence showing that WDR5 binds the Win motifs of MLL2-4, SET1A and SET1B. Comparative analysis of WDR5-Win complexes reveals that binding of the Win motifs is achieved by the plasticity of WDR5 peptidyl-arginine-binding cleft allowing the C-terminal ends of the Win motifs to be maintained in structurally divergent conformations. Consistently, enzymatic assays reveal that WDR5 plays an important role in the optimal stimulation of MLL2-4, SET1A and SET1B methyltransferase activity by the RbBP5-ASH2L heterodimer. Overall, our findings illustrate the function of WDR5 in scaffolding the SET1 family of KMTs and further emphasize on the important role of WDR5 in regulating global histone H3 Lys-4 methylation.

Show MeSH
Related in: MedlinePlus