Human initiation factor eIF3 subunit b interacts with HCV IRES RNA through its N‐terminal RNA recognition motif

Many viral mRNAs contain a 5′‐UTR RNA element called internal ribosome‐entry site (IRES), which bypasses the requirement of some canonical initiation factors allowing cap‐independent translation. The IRES of hepatitis‐C virus drives translation by directly recruiting 40S ribosomal subunits and binds to eIF3 which plays a critical role in both cap‐dependent and cap‐independent translation. However, the molecular basis for eIF3 activity in either case remains enigmatic. Here we report that subunit b of the eIF3 complex directly binds to HCV IRES domain III via its N‐terminal‐RRM. Because eIF3b was previously shown to be involved in eIF3j binding, biological implications are discussed.