Understanding the RNA Binding Molecular Mechanisms IN IUR of Human LARP1

Shiva Adhikari, Robert Silvers

Florida State University, Tallahassee

LARP1 (La-Related Protein 1) is an RNA-binding protein that is primarily involved in the translation and stability of mRNAs. Human LARP1 (Hs LARP1) is found to play a role in post-translation regulation of 5’ terminal oligopyrimidine motif (5’ TOP), a cis-regulatory RNA component of the 7-methylguanosine cap of TOP mRNAs. The La-module (LaMOD) of HsLARP1 has been shown to bind with 5’TOP and 3’ poly(A) motifs of mRNA compared to other LARPs. As LARP1 has been found to repress TOP mRNA translation via the C-terminal DM15 region, the role of the N-terminal La-Module in the regulation of TOP mRNAs is still ambiguous. Since it has been known that LaMOD in HsLARP1 has a folded La motif (La-M) domain followed by an intrinsically unstructured region (IUR). Here, we investigate the dynamics of the unstructured region of human LARP1 along with its effects on the activity of La-module. We devised the constructs to express and purify IUR regions of humans LARP1 using a self-cleaving peptide N-pro EDDIE to study the RNA-binding mechanisms followed by structure characterization using NMR experiments.

In this particular research, we expressed and purified the Intrinsically Unstructured regions (IUR) of human LARP1, and set up multiple biophysical experiments such as; Electrophoretic Mobility shit assay (EMSA), Microscale Thermophoresis (MST) to study the mechanism of RNA-binding interaction of La-related protein 1 (LARP1). We then utilized the use solution-state Nuclear magnetic resonance spectroscopy (NMR) to structurally characterize the interactions between RNA and LARP1.