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

doi:10.1016/j.celrep.2021.109663

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

Microbiology-Immunology

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

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 language	English (US)
Article number	109663
Journal	Cell reports
Volume	36
Issue number	10
DOIs	https://doi.org/10.1016/j.celrep.2021.109663
State	Published - Sep 7 2021

Funding

We thank the Arnold and Mabel Beckman Center for Cryo-EM and Center for High Performance Computing at the University of Utah for support in data collection and data processing, respectively. This work was supported by grants from the NIH to M.G.R. ( F31 AI152548 ), P.S.S. ( R35 GM133772 ), and D.W. ( R01 AI127456 and Diversity Supplement R01 AI127456-S ). We thank the Arnold and Mabel Beckman Center for Cryo-EM and Center for High Performance Computing at the University of Utah for support in data collection and data processing, respectively. This work was supported by grants from the NIH to M.G.R. (F31 AI152548), P.S.S. (R35 GM133772), and D.W. (R01 AI127456 and Diversity Supplement R01 AI127456-S). M.G.R. generated cell lines and performed the bulk of functional studies, with assistance from N.M. N.M. and H.A. performed and analyzed reporter assays. M.S. isolated ribosomes and analyzed cryo-EM data with P.S.S. P.S.S. and D.W. oversaw the project. M.G.R. drafted the manuscript. P.S.S. and D.W. contributed to editing. All authors reviewed and approved the manuscript. The authors declare no competing interests. One or more of the authors of this paper self-identifies as an underrepresented ethnic minority in science. One or more of the authors of this paper received support from a program designed to increase minority representation in science.

Keywords

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

ASJC Scopus subject areas

General Biochemistry, Genetics and Molecular Biology

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10.1016/j.celrep.2021.109663

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title = "Negative charge in the RACK1 loop broadens the translational capacity of the human ribosome",

abstract = "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.",

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AU - Shen, Peter S.

AU - Walsh, Derek

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

Abstract

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Keywords

ASJC Scopus subject areas

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