MCDB seminar will be from Jahree Sosa from the Berman lab will be presenting their research titled:
Title: Examining the effects of an extension in plant LARP1 on the structure and function of its DM15 region
Friday, March 21, 2025
A219B Langley Hall
12:00 PM
The protein production capacity of eukaryotic cells relies on the careful regulation of ribosome biogenesis. One master regulatory switch of this process in eukaryotic systems is a protein kinase complex, target of rapamycin complex 1 (TORC1). TORC1 integrates cellular cues to regulate the cell’s capacity for protein synthesis by targeting other proteins involved in ribosome biogenesis and altering their activity via post-translational modification. One target of TORC1 is La-related protein 1 (LARP1), a ubiquitous eukaryotic RNA-binding protein with at least 2 RNA-binding domains that each has the ability to selectively and specifically interact with distinct RNA structures and sequences. The mRNA cap-binding DM15 domain of all studied LARP1 proteins to date has been shown to bind and regulate the translation of terminal oligo pyrimidine (TOP) mRNAs, a class of eukaryotic RNAs that encodes the protein components of the translation machinery. The domain binds TOP mRNA sequences through direct recognition of the m7G cap and characteristic +1C of TOP mRNAs by conserved residues. Interestingly, plant LARP1 proteins are predicted to have a DM15 region with an extended C-terminal end, as compared to all other organisms. To investigate the putatively extended structure and RNA-binding activity of plant LARP1 DM15 domains, I am investigating the structure and biochemical behavior of the LARP1a DM15 domain of model plant organism, Arabidopsis thaliana (atDM15).
The crystal structure of atDM15 bound to m7GTP resolved to 2.0 Å resolution reveals that atDM15 contains an additional alpha helix C-terminal to the RNA-binding surface of DM15 domains; the orientation of the C-terminal helix creates a possible steric block, thereby forcing the alignment of the RNA to bind in the +1G pocket. atDM15 also recognizes the m7GTP cap by the same conserved residues and pocket as all other studied DM15 domains to date. Additionally, early biochemical characterization of atDM15 suggests a preference for binding capped RNA sequences that are pyrimidine-rich. Future work will use mutagenesis to examine interesting differences in the RNA-binding site and elsewhere in the structure to assess the contribution of these residues to the RNA-binding activity of atDM15.