Poster abstracts
Poster number 159 submitted by Geqi Li
The role of the Nop2 N-terminal IDR in yeast ribosome biogenesis
Stefanie Hedayati (Department of Biological Sciences, Carnegie Mellon University), Geqi Li (Department of Biological Sciences, Carnegie Mellon University), Nadia Ghetie (Department of Biological Sciences, Carnegie Mellon University), Collin Bachert (Department of Biological Sciences, Carnegie Mellon University), John L. Woolford Jr. (Department of Biological Sciences, Carnegie Mellon University)
Abstract:
Ribosome biogenesis in yeast requires the coordinated action of ~200 assembly factors (AFs), more than half of which contain intrinsically disordered regions (IDRs) conserved across eukaryotes. Although IDRs are increasingly recognized as critical mediators in macromolecular interactions and cellular physiology sensing, their functions in ribosome assembly remain poorly understood. Cryo-EM structures of pre-ribosome intermediates have defined the positions of many AFs, ribosomal proteins, and compacted rRNA, yet the conformational heterogeneity of IDRs leaves their roles unresolved.
To investigate how IDRs influence ribosome maturation, we focused on the N-terminal IDR of the ribosome assembly factor Nop2, which consists of a stretch of basic residues followed by an extended acidic tract. Partial deletions, charge scrambling, and block reorganization within this region produced a dominant-negative slow-growth phenotype, blocking assembly prior to Nop2 release from pre-ribosomes.
We are examining Nop2 IDR sequences from fungi and metazoa. We have begun by replacing the N-term IDR with that of Schizosaccharomyces pombe, Drosophila, and Humans. While the metazoan counterparts failed to complement, the S.pombe IDR enabled slow growth. Ongoing work is probing how IDR charge distribution shapes dynamic interactions within pre-ribosomal particles and drives large-scale conformational transitions, using cryo-EM analysis of nop2 mutant complexes.
References:
LaPeruta AJ, Micic J, Woolford JL Jr. (2022). Principles governing release of pre-ribosomes from nucleolus to nucleoplasm in yeast. Nucleic Acids Res 51(20):10867–83.
LaPeruta AJ, Hedayati S, Micic J, Fitzgerald F, Kim D, Oualline G, Woolford JL Jr. (2023). Puf6, Nog2, uL2 & eL43 cooperate to release nascent 60S subunits. Nucleic Acids Res 51(20):11277–90.
Ayers TN, Woolford JL Jr. (2024). Roles of ribosomal proteins in nucleolar 60S assembly in yeast. Biomolecules 14(8):975.
Lyons H, Veettil RT, Pradhan P, Fornero C, De La Cruz N, Ito K, Eppert M, Roeder RG, Sabari BR. (2023). Functional partitioning of transcriptional regulators by charge blocks. Cell 186(2):327–45.e28.
Keywords: Ribosome biogenesis, Intrinsically disordered regions, Assembly factors