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. Author manuscript; available in PMC: 2015 Dec 30.
Published in final edited form as: Annu Rev Biochem. 2013;82:81–118. doi: 10.1146/annurev-biochem-072711-165700

Figure 6.

Figure 6

Structures of expanded and paired modules bound to methyl-arginine and unmodified arginine-containing peptides. (a) The 2.8-Å crystal structure of the complex of the extended Tudor module of SND1 bound to R15me2s-containing N-terminal PIWI peptide, Protein Data Bank (PDB) reference 3NTI. The core fold of the Tudor domain is shown in blue, and the extensions are shown in green. The R15me2s-containing N-terminal PIWI peptide can be traced from Arg11 to Arg17 (R11 to R17). (b) Positioning of R15me2s in the aromatic-lined cage pocket of the Tudor domain in the SND1 complex. (c) The 1.8-Å crystal structure of the complex of the PHD finger of UHRF1 bound to the H3(1–9) peptide (PDB: 3SOU). The bound H3 peptide can be traced from Ala1 to Arg8 (A1 to R8). Note the network of hydrogen bonds involving Arg2 (R2) and residues on the PHD finger. (d) The 1.5-Å crystal structure of the complex of the WD40 motif of WDR5 bound to the H3(1–9)K4me2 peptide. The bound K4me2-containing peptide can be traced from Ala1 to Arg8 (A1 to R8) (PDB: 2H6N). (e) Intermolecular hydrogen-bonding interactions stabilizing insertion of Arg2 (R2) into the central channel of the WD40 motif in the H3(1–9)K4me2-WDR5 complex. (f) Insertion of symmetrical Arg2me2 (R2me2s) into the central channel of the WD40 motif in the H3(1–15)R2me2s-WDR5 complex solved at 1.9 Å (PDB: 4A7J). (g) The 3.18-Å crystal structure of the complex of the chromodomains and ankyrin repeats of Arabidopsis thaliana cpSRP43 bound to an Arg-Arg-Lys-Arg (RRKR)-containing peptide (PDB: 3UI2). The side chains of Arg536 (R536) and Arg537 (R537) of the bound RRKR-containing peptide from Gln528 to Lys540 (Q528-K540) are positioned in adjacent pockets at the interface between the fourth ankyrin repeat and the second chromodomain in the complex. (h) Position of Arg536 (R536) of the RRKR-containing peptide within an aromatic-lined cage pocket in the complex. (i) Positioning of Arg537 (R537) of the RRKR-containing peptide in a pocket lined by a Trp and two acidic side chains in the complex. Abbreviation: C, C terminus.