Structural Basis of Binding of P-body-associated Proteins GW182 and Ataxin-2 by the Mlle Domain of Poly(A)-binding Protein

• Published in: The Journal of biological chemistry 2010-04, Vol.285 (18), p.13599-13606
• Main Authors: Kozlov, Guennadi, Safaee, Nozhat, Rosenauer, Angelika, Gehring, Kalle
• Format: Article
• Language: English
• Subjects: Ataxin-2; Ataxins; Autoantigens - chemistry; Autoantigens - genetics; Autoantigens - metabolism; Binding Sites - physiology; Cytoplasmic Granules - chemistry; Cytoplasmic Granules - genetics; Cytoplasmic Granules - metabolism; Deadenylation; Humans; Multiprotein Complexes - chemistry; Multiprotein Complexes - genetics; Multiprotein Complexes - metabolism; Mutagenesis; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; P-body; PAM2; Peptides - chemistry; Peptides - genetics; Peptides - metabolism; Poly(A)-binding Protein; Poly(A)-Binding Protein I - chemistry; Poly(A)-Binding Protein I - genetics; Poly(A)-Binding Protein I - metabolism; Polyadenylation; Protein Binding - physiology; Protein Biosynthesis - physiology; Protein Structure and Folding; Protein Structure, Quaternary; Protein Structure, Tertiary; RNA; RNA Processing; RNA Processing, Post-Transcriptional - physiology; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA-Binding Proteins; Stress Granule; Structure-Activity Relationship; Translation Control; X-ray Crystallography
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M109.089540

Poly(A)-binding protein (PABPC1) is involved in multiple aspects of mRNA processing and translation. It is a component of RNA stress granules and binds the RNA-induced silencing complex to promote degradation of silenced mRNAs. Here, we report the crystal structures of the C-terminal Mlle (or PABC) domain in complex with peptides from GW182 (TNRC6C) and Ataxin-2. The structures reveal overlapping binding sites but with unexpected diversity in the peptide conformation and residues involved in binding. The mutagenesis and binding studies show low to submicromolar binding affinity with overlapping but distinct specificity determinants. These results rationalize the role of the Mlle domain of PABPC1 in microRNA-mediated mRNA deadenylation and suggest a more general function in the assembly of cytoplasmic RNA granules.