The N-terminal K Homology Domain of the Poly(rC)-binding Protein Is a Major Determinant for Binding to the Poliovirus 5′-Untranslated Region and Acts as an Inhibitor of Viral Translation

Deborah Silvera,Andrea V Gamarnik,Raul Andino

doi:10.1074/jbc.274.53.38163

Deborah Silvera, Andrea V Gamarnik + Show 1 more

Open Access

https://doi.org/10.1074/jbc.274.53.38163

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Abstract

The poly(rC)-binding proteins (PCBP1 and PCBP2) are RNA-binding proteins whose RNA recognition motifs are composed of three K homology (KH) domains. These proteins are involved in both the stabilization and translational regulation of several cellular and viral RNAs. PCBP1 and PCBP2 specifically interact with both the 5'-element known as the cloverleaf structure and the large stem-loop IV RNA of the poliovirus 5'-untranslated region. We have found that the first KH domain of PCBP2 (KH1) specifically interacts with the viral RNAs, and together with viral protein 3CD, KH1 forms a high affinity ternary ribonucleoprotein complex with the cloverleaf RNA, resembling the full-length PCBP protein. Furthermore, KH1 acts as a dominant-negative mutant to inhibit translation from a poliovirus reporter gene in both Xenopus laevis oocytes and HeLa cell in vitro translation extracts.

Highlights

Translation in eukaryotic cells is a highly regulated process involving a complex protein machinery
No other known RNA-binding motif is found within the PCBPs, and the K homologous (KH) domains are able to function as discreet and independent nucleic acid-binding units: expression of each of the three domains individually demonstrated that the KH1 and KH3 domains of PCBP1 and PCBP2 bind to poly(rC) homopolymers [19]
Role of KH Domains in PCBP Binding to the Poliovirus 5Ј-UTR—We have mapped the determinants for PCBP2 binding to two RNA structures of the poliovirus 5Ј-UTR, the cloverleaf and stem-loop IV

Summary

Introduction

Translation in eukaryotic cells is a highly regulated process involving a complex protein machinery. These proteins facilitate viral translation through the interaction with both the first stemloop domain (which folds into a cloverleaf-like structure) and stem-loop IV of the poliovirus 5Ј-UTR [5,6,7,8].

Results

Conclusion