Negative charge in the RACK1 loop broadens the translational capacity of the human ribosome

Madeline G. Rollins, Manidip Shasmal, Nathan Meade, Helen Astar, Peter S. Shen*, Derek Walsh*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Although the roles of initiation factors, RNA binding proteins, and RNA elements in regulating translation are well defined, how the ribosome functionally diversifies remains poorly understood. In their human hosts, poxviruses phosphorylate serine 278 (S278) at the tip of a loop domain in the small subunit ribosomal protein RACK1, thereby mimicking negatively charged residues in the RACK1 loops of dicot plants and protists to stimulate translation of transcripts with 5′ poly(A) leaders. However, how a negatively charged RACK1 loop affects ribosome structure and its broader translational output is not known. Here, we show that although ribotoxin-induced stress signaling and stalling on poly(A) sequences are unaffected, negative charge in the RACK1 loop alters the swivel motion of the 40S head domain in a manner similar to several internal ribosome entry sites (IRESs), confers resistance to various protein synthesis inhibitors, and broadly supports noncanonical modes of translation.

Original languageEnglish (US)
Article number109663
JournalCell reports
Issue number10
StatePublished - Sep 7 2021


  • IRES
  • alternative initiation
  • cryo-EM
  • mRNA specification
  • post-translational modification
  • protein synthesis
  • ribosome
  • selective translation
  • structure

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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