2. Academic Validation
  3. Nascent alt-protein chemoproteomics reveals a pre-60S assembly checkpoint inhibitor

Nascent alt-protein chemoproteomics reveals a pre-60S assembly checkpoint inhibitor

  • Nat Chem Biol. 2022 Jun;18(6):643-651. doi: 10.1038/s41589-022-01003-9.
Xiongwen Cao 1 2,  Alexandra Khitun 1 2,  Cecelia M Harold 3,  Carson J Bryant 4,  Shu-Jian Zheng 1 2,  Susan J Baserga 3 4 5,  Sarah A Slavoff 6 7 8
Affiliations

Affiliations

  • 1 Department of Chemistry, Yale University, New Haven, CT, USA.
  • 2 Institute of Biomolecular Design and Discovery, Yale University, West Haven, CT, USA.
  • 3 Department of Genetics, Yale University School of Medicine, New Haven, CT, USA.
  • 4 Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA.
  • 5 Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT, USA.
  • 6 Department of Chemistry, Yale University, New Haven, CT, USA. sarah.slavoff@yale.edu.
  • 7 Institute of Biomolecular Design and Discovery, Yale University, West Haven, CT, USA. sarah.slavoff@yale.edu.
  • 8 Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA. sarah.slavoff@yale.edu.
PMID: 35393574 DOI: 10.1038/s41589-022-01003-9
Abstract

Many unannotated microproteins and alternative proteins (alt-proteins) are coencoded with canonical proteins, but few of their functions are known. Motivated by the hypothesis that alt-proteins undergoing regulated synthesis could play important cellular roles, we developed a chemoproteomic pipeline to identify nascent alt-proteins in human cells. We identified 22 actively translated alt-proteins or N-terminal extensions, one of which is post-transcriptionally upregulated by DNA damage stress. We further defined a nucleolar, cell-cycle-regulated alt-protein that negatively regulates assembly of the pre-60S ribosomal subunit (MINAS-60). Depletion of MINAS-60 increases the amount of cytoplasmic 60S ribosomal subunit, upregulating global protein synthesis and cell proliferation. Mechanistically, MINAS-60 represses the rate of late-stage pre-60S assembly and export to the cytoplasm. Together, these results implicate MINAS-60 as a potential checkpoint inhibitor of pre-60S assembly and demonstrate that chemoproteomics enables hypothesis generation for uncharacterized alt-proteins.

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