Dissecting Monomer-Dimer Equilibrium of an RNase P Protein Provides Insight Into the Synergistic Flexibility of 5’ Leader Pre-tRNA Recognition

Authors

Danyun Zeng, Marquette University
Ainur Abzhanova, Marquette University
Benjamin P. Brown, Vanderbilt University
Nicholas J. Reiter, Marquette UniversityFollow

Document Type

Article

Publication Date

9-2021

Publisher

Frontiers Media S.A.

Source Publication

Frontiers in Molecular Biosciences

Source ISSN

2296-889x

Abstract

Ribonuclease P (RNase P) is a universal RNA-protein endonuclease that catalyzes 5’ precursor-tRNA (ptRNA) processing. The RNase P RNA plays the catalytic role in ptRNA processing; however, the RNase P protein is required for catalysis in vivo and interacts with the 5’ leader sequence. A single P RNA and a P protein form the functional RNase P holoenzyme yet dimeric forms of bacterial RNase P can interact with non-tRNA substrates and influence bacterial cell growth. Oligomeric forms of the P protein can also occur in vitro and occlude the 5’ leader ptRNA binding interface, presenting a challenge in accurately defining the substrate recognition properties. To overcome this, concentration and temperature dependent NMR studies were performed on a thermostable RNase P protein from Thermatoga maritima. NMR relaxation (R₁, R₂), heteronuclear NOE, and diffusion ordered spectroscopy (DOSY) experiments were analyzed, identifying a monomeric species through the determination of the diffusion coefficients (D) and rotational correlation times (τ_c). Experimental diffusion coefficients and τ_c values for the predominant monomer (2.17 ± 0.36 * 10⁻¹⁰ m²/s, τ_c = 5.3 ns) or dimer (1.87 ± 0.40* 10⁻¹⁰ m²/s, τ_c = 9.7 ns) protein assemblies at 45°C correlate well with calculated diffusion coefficients derived from the crystallographic P protein structure (PDB 1NZ0). The identification of a monomeric P protein conformer from relaxation data and chemical shift information enabled us to gain novel insight into the structure of the P protein, highlighting a lack of structural convergence of the N-terminus (residues 1–14) in solution. We propose that the N-terminus of the bacterial P protein is partially disordered and adopts a stable conformation in the presence of RNA. In addition, we have determined the location of the 5’ leader RNA in solution and measured the affinity of the 5’ leader RNA–P protein interaction. We show that the monomer P protein interacts with RNA at the 5’ leader binding cleft that was previously identified using X-ray crystallography. Data support a model where N-terminal protein flexibility is stabilized by holoenzyme formation and helps to accommodate the 5’ leader region of ptRNA. Taken together, local structural changes of the P protein and the 5’ leader RNA provide a means to obtain optimal substrate alignment and activation of the RNase P holoenzyme.

Comments

Published version. Frontiers in Molecular Biosciences, Vol. 8 (September 3, 2021): 730274. DOI. © 2021 Zeng, Abzhanova, Brown and Reiter. Used with permission.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Zeng, Danyun; Abzhanova, Ainur; Brown, Benjamin P.; and Reiter, Nicholas J., "Dissecting Monomer-Dimer Equilibrium of an RNase P Protein Provides Insight Into the Synergistic Flexibility of 5’ Leader Pre-tRNA Recognition" (2021). Chemistry Faculty Research and Publications. 1046.
https://epublications.marquette.edu/chem_fac/1046