Mammalian Hsp70 and Hsp110 proteins bind to RNA motifs involved in mRNA stability.

T Henics, E Nagy, H J Oh, P Csermely, A von Gabain, J R Subjeck

The Journal of biological chemistry 1999 Jun 11

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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 alpha-helical structure or the alpha-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.

Citation

T Henics, E Nagy, H J Oh, P Csermely, A von Gabain, J R Subjeck. Mammalian Hsp70 and Hsp110 proteins bind to RNA motifs involved in mRNA stability. The Journal of biological chemistry. 1999 Jun 11;274(24):17318-24