Structural inventory of native ribosomal ABCE1-43S pre-initiation complex

ABSTRACT: In eukaryotic translation, the termination and recycling phases are linked to subsequent initiation by persistence of several factors. These comprise the large eIF3 complex, eIF3j (Hcr1 in yeast) and the ATP-binding cassette protein ABCE1 (Rli1 in yeast). The ATPase is mainly active as a recycling factor, but it can remain bound to the dissociated 40S subunit until formation of 43S pre-initiation complexes. However, its functional role and native architectural context remains largely enigmatic. Here, we present an architectural inventory of native yeast and human ABCE1-containing pre-initiation complexes by cryo-EM. We found that ABCE1 was mostly associated with early 43S but also later 48S phases of initiation. It adopted a novel hybrid conformation of its nucleotide binding sites, which was stabilized by the N-terminus of eIF3j. Further, eIF3j occupied the mRNA entry channel via its ultimate C-terminus explaining its antagonistic role with respect to mRNA binding. Moreover, the native human samples provided a near-complete molecular picture of the architecture and sophisticated interaction network of the 43S-bound eIF3 complex and also the eIF2 ternary complex containing the initiator tRNA.

INSTRUMENT(S):

ORGANISM(S): Saccharomyces Cerevisiae (baker's Yeast)

SUBMITTER: Mia Potocnjak  

LAB HEAD: Roland Beckmann

PROVIDER: PXD020849 | Pride | 2020-10-16

REPOSITORIES: Pride