Mammalian Hsp70 and Hsp110 Proteins Bind to RNA Motifs Involved in mRNA Stability

• Published in: The Journal of biological chemistry Vol. 274; no. 24; pp. 17318 - 17324
• Main Authors: Henics, T, Nagy, E, Oh, H J, Csermely, P, von Gabain, A, Subjeck, J R
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 11.06.1999
• Subjects: 3' Untranslated Regions; Adenosine Triphosphate - pharmacology; Base Composition; Base Sequence; Binding Sites; Carrier Proteins - metabolism; HSC70 Heat-Shock Proteins; HSP110 Heat-Shock Proteins; HSP70 Heat-Shock Proteins - genetics; HSP70 Heat-Shock Proteins - metabolism; Lactalbumin; Molecular Sequence Data; Mutation; Precipitin Tests; Protein Binding - drug effects; RNA, Messenger - metabolism; RNA-Binding Proteins - metabolism; Sequence Deletion
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.274.24.17318

In this study, in vitro RNA binding by members of the mammalian 70-kDa heat shock protein (Hsp) family was examined. We show that Hsp/Hsc70 and Hsp110 proteins preferentially bound AU-rich RNA in vitro . Inhibition of RNA binding by ATP suggested the involvement of the N-terminal ATP-binding domain. By using deletion mutants of Hsp110 protein, a diverged Hsp70 family member, RNA binding was localized to the N-terminal ATP-binding domain of the molecule. The C-terminal peptide-binding domain did not bind RNA, but its engagement by a peptide substrate abrogated RNA binding by the N terminus of the protein. Interestingly, removal of the C-terminal α-helical structure or the α-loop domain unique to Hsp110 immediately downstream of the peptide-binding domain, but not both, resulted in considerably increased RNA binding as compared with the wild type protein. Finally, a 70-kDa activity was immunoprecipitated from RNA-protein complexes formed in vitro between cytoplasmic proteins of human lymphocytes and AU-rich RNA. These findings support the idea that certain heat shock proteins may act as RNA-binding entities in vivo to guide the appropriate folding of RNA substrates for subsequent regulatory processes such as mRNA degradation and/or translation.