Ribosomes are responsible for the rapid and accurate production of all the thousands of different proteins in cells in all forms of life on earth. The ability of these molecuar machines to do this depends upon a complex structure that is both stable and flexible, allowing it to interact with ligands in a dynamic fashion. The mature ribosome has binding sites for multiple ligands, including initiation factors, elongation factors, termination factors, tRNAs and mRNA, and it must ratchet between multiple stable conformations, moving tRNAs in and out at enormous rates. The accurate assembly of a fully functional eukaryotic ribosome involves over 200 accessory assembly factors, whose function, in many cases, is still unknown. However much recent excitement has focused on the role of some of these proteins in quality control checkpoints that occur late in the biogenesis process in the cytoplasm. We have recently proposed that the 60S subunit undergoes a cytoplasmic "test drive" in which newly assembled ribosomes are tested for function by biogenesis factors that structurally mimic translation factors. This proposal seeks to understand the mechanism of 60S maturation, focusing on the last steps of this pathway, the release of Tif6 and Nmd3, which, we believe, comprise the primary quality control checks on the large subunit. This proposal is directed at understanding quality control mechanisms that assess the functional and structural integrity of the large ribosomal subunit. This proposal builds on our recent results from the previous funding period suggesting that the newly assembled subunit undergoes a "test drive" that uses molecular mimics of translation factors prior to bona fide translation. In collaboration with Dr Jan Cools (VIB, Belgium) we have also recently shown that a defect in this quality control check is associated with ~8% of pediatric acute T-cell leukemia samples. Defects in this step are also associated with Shwachman-Diamond syndrome, an inherited disease that manifests in bone marrow failure, pancreatic dysfunction and predisposition to cancers among other conditions. These results highlight the importance of understanding the mechanism of this quality control step for its potential target for new drug therapies.

Public Health Relevance

This project delineates essential and fundamental molecular pathways that are conserved throughout eukaryotes. Understanding these pathways and how they are integrated with other cellular pathways will provide the intellectual underpinning for investigator carrying out translational research. This project also defines the mechanism of a critical quality control step in assembling ribosomes, the machines that are responsible for translating our genetic code into proteins. Two human diseases, Acute T-cell lymphoblastic leukemia and Shwachman-Diamond syndrome, are known to be associated with defects in this quality control step.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
2R01GM053655-18
Application #
8723619
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Bender, Michael T
Project Start
Project End
Budget Start
Budget End
Support Year
18
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Texas Austin
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
City
Austin
State
TX
Country
United States
Zip Code
78712
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Sulima, Sergey O; Gulay, Suna P; Anjos, Margarida et al. (2014) Eukaryotic rpL10 drives ribosomal rotation. Nucleic Acids Res 42:2049-63
Sardana, Richa; Zhu, Jieyi; Gill, Michael et al. (2014) Physical and functional interaction between the methyltransferase Bud23 and the essential DEAH-box RNA helicase Ecm16. Mol Cell Biol 34:2208-20
Sulima, Sergey O; Patchett, Stephanie; Advani, Vivek M et al. (2014) Bypass of the pre-60S ribosomal quality control as a pathway to oncogenesis. Proc Natl Acad Sci U S A 111:5640-5
Hartl, Tom A; Ni, Julie; Cao, Jian et al. (2013) Regulation of ribosome biogenesis by nucleostemin 3 promotes local and systemic growth in Drosophila. Genetics 194:101-15
Castle, Christopher D; Sardana, Richa; Dandekar, Varada et al. (2013) Las1 interacts with Grc3 polynucleotide kinase and is required for ribosome synthesis in Saccharomyces cerevisiae. Nucleic Acids Res 41:1135-50
De Keersmaecker, Kim; Atak, Zeynep Kalender; Li, Ning et al. (2013) Exome sequencing identifies mutation in CNOT3 and ribosomal genes RPL5 and RPL10 in T-cell acute lymphoblastic leukemia. Nat Genet 45:186-90
Sardana, Richa; White, Joshua P; Johnson, Arlen W (2013) The rRNA methyltransferase Bud23 shows functional interaction with components of the SSU processome and RNase MRP. RNA 19:828-40
Hines, Justin K; Li, Xiaomo; Du, Zhiqiang et al. (2011) [SWI], the prion formed by the chromatin remodeling factor Swi1, is highly sensitive to alterations in Hsp70 chaperone system activity. PLoS Genet 7:e1001309
Sengupta, Jayati; Bussiere, Cyril; Pallesen, Jesper et al. (2010) Characterization of the nuclear export adaptor protein Nmd3 in association with the 60S ribosomal subunit. J Cell Biol 189:1079-86

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