Poster abstracts
Poster number 169 submitted by Lizette Zavala
Unraveling the biochemical characteristics of target of EGR1 (TOE1) linked to pontocerebellar hypoplasia
Lizette Zavala (Biochemistry and Molecular Biology, University of Chicago), Magdalena Sobien (Biochemistry and Molecular Biology, University of Chicago), Cassandra Hayne (Biochemistry and Molecular Biology, University of Chicago)
Abstract:
Target of EGR1 (TOE1) is 3'-to-5' Cajal associated-deadenylase involved in the maturation of Pol-II transcribed small nuclear RNAs (snRNAs). In addition to trimming poly(A) tails, TOE1 has been previously shown to have exonuclease activity—a unique feature to this deadenylase. Additionally, mutations found within the TOE1 gene have been linked to Pontocerebellar Hypoplasia type 7 (PCH7) and seem to disrupt proper maturation for snRNA targets. PCH7 is a rare recessive neurodevelopmental and neurodegenerative disease characterized by gonad abnormalities, atrophy to the pons and cerebellum, and leads to early mortality. Currently, the mechanism by which these PCH7-linked mutations impact TOE1’s biochemical characteristics is not known. We utilized AlphaFold (AF) to generate computationally predicted structural models of TOE1 with which to study the molecular environment surrounding residues linked to PCH7. Based on the AF models, we hypothesized that PCH7-linked mutations could impact thermal stability, activity, or oligomerization.
Indeed, our biochemical assays demonstrate variability in the biochemical properties of TOE1 variants, compared wild-type TOE1. We found that eight PCH7-linked variants have significantly lower thermal stability compared to WT. Three PCH7-linked variants exhibit impaired deadenylase activity, and all but two PCH7-linked variants had impaired exonuclease activity. Finally, we provide evidence for dimerization of WT TOE1 and found that one mutation, F148Y, shifts the TOE1 oligomer to a monomer. Together, our findings highlight the many facets of TOE1’s biochemical properties are impacted by the various PCH7 mutations tested.
References:
This work is covered in a recent pre-print: Zavala, L., Sobien, M., & Hayne, C. K. (2025). Biochemical characterizations of Pontocerebellar Hypoplasia linked mutations of Target of Egr1 (TOE1) reveal impacts on thermal stability, ribonuclease activity, and oligomerization. bioRxiv: the preprint server for biology, 2025.09.18.672001. https://doi.org/10.1101/2025.09.18.672001
Keywords: RNA processing, Deadenylase, Exonuclease