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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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MLL3 methylates histone H3 in the absence of the core complex subunits. Comparative analysis of MLL's enzymatic activity in the absence of the core complex subunits. Assays were performed in the presence of 5.0 µM of enzymes. Activity is represented as in Figure 4.
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gkr1235-F5: MLL3 methylates histone H3 in the absence of the core complex subunits. Comparative analysis of MLL's enzymatic activity in the absence of the core complex subunits. Assays were performed in the presence of 5.0 µM of enzymes. Activity is represented as in Figure 4.

Mentions: Following the identification that the WDR5–RbBP5–ASH2L complex stimulates all members of the SET1 family, we sought to evaluate the methylation of histone H3 by MLL1-4 in the absence of the core complex subunits. To examine the catalytic activity of each MLL, we incubated each KMT with a histone H3 peptide and a tritiated cofactor. As shown in Figure 5, we failed to detect histone H3 methylation by MLL1, MLL2 and MLL4 while a similar assay performed with MLL3 resulted in a notable accumulation of the methylated peptide. These observations suggest that MLL3 enzymatic activity may play a role independent of the WDR5–RbBP5–ASH2L complex.Figure 5.


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)

MLL3 methylates histone H3 in the absence of the core complex subunits. Comparative analysis of MLL's enzymatic activity in the absence of the core complex subunits. Assays were performed in the presence of 5.0 µM of enzymes. Activity is represented as in Figure 4.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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

gkr1235-F5: MLL3 methylates histone H3 in the absence of the core complex subunits. Comparative analysis of MLL's enzymatic activity in the absence of the core complex subunits. Assays were performed in the presence of 5.0 µM of enzymes. Activity is represented as in Figure 4.
Mentions: Following the identification that the WDR5–RbBP5–ASH2L complex stimulates all members of the SET1 family, we sought to evaluate the methylation of histone H3 by MLL1-4 in the absence of the core complex subunits. To examine the catalytic activity of each MLL, we incubated each KMT with a histone H3 peptide and a tritiated cofactor. As shown in Figure 5, we failed to detect histone H3 methylation by MLL1, MLL2 and MLL4 while a similar assay performed with MLL3 resulted in a notable accumulation of the methylated peptide. These observations suggest that MLL3 enzymatic activity may play a role independent of the WDR5–RbBP5–ASH2L complex.Figure 5.

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