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Proc Natl Acad Sci U S A. 2017 Jul 11;114(28):E5530-E5538. doi: 10.1073/pnas.1703133114. Epub 2017 Jun 26.

Grc3 programs the essential endoribonuclease Las1 for specific RNA cleavage.

Author information

1
Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709.
2
Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
3
Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709.
4
Signal Transduction Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709; robin.stanley@nih.gov.

Abstract

Las1 is a recently discovered endoribonuclease that collaborates with Grc3-Rat1-Rai1 to process precursor ribosomal RNA (rRNA), yet its mechanism of action remains unknown. Disruption of the mammalian Las1 gene has been linked to congenital lethal motor neuron disease and X-linked intellectual disability disorders, thus highlighting the necessity to understand Las1 regulation and function. Here, we report that the essential Las1 endoribonuclease requires its binding partner, the polynucleotide kinase Grc3, for specific C2 cleavage. Our results establish that Grc3 drives Las1 endoribonuclease cleavage to its targeted C2 site both in vitro and in Saccharomyces cerevisiae. Moreover, we observed Las1-dependent activation of the Grc3 kinase activity exclusively toward single-stranded RNA. Together, Las1 and Grc3 assemble into a tetrameric complex that is required for competent rRNA processing. The tetrameric Grc3/Las1 cross talk draws unexpected parallels to endoribonucleases RNaseL and Ire1, and establishes Grc3/Las1 as a unique member of the RNaseL/Ire1 RNA splicing family. Together, our work provides mechanistic insight for the regulation of the Las1 endoribonuclease and identifies the tetrameric Grc3/Las1 complex as a unique example of a protein-guided programmable endoribonuclease.

KEYWORDS:

HEPN domain; Las1; endoribonuclease; polynucleotide kinase; pre-rRNA processing

PMID:
28652339
PMCID:
PMC5514736
DOI:
10.1073/pnas.1703133114
[Indexed for MEDLINE]
Free PMC Article

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