Backbone and side chain NMR assignments for the ribosome binding factor A (RbfA) from Staphylococcus aureus

Structural aspects of RimP binding on small ribosomal subunit from Staphylococcus aureus

Ribosome biogenesis is an energy-intense multistep process where even minimal defects can cause severe phenotypes up to cell death. Ribosome assembly is facilitated by biogenesis factors such as ribosome assembly factors. These proteins facilitate the interaction of ribosomal proteins with rRNA and correct rRNA folding. One of these maturation factors is RimP which is required for efficient 16S rRNA processing and 30S ribosomal subunit assembly. Here, we describe the binding mode of Staphylococcus aureus RimP to the small ribosomal subunit and present a 4.2 Å resolution cryo-EM reconstruction of the 30S-RimP complex. Together with the solution structure of RimP solved by NMR spectroscopy and RimP-uS12 complex analysis by EPR, DEER, and SAXS approaches, we show the specificity of RimP binding to the 30S subunit from S. aureus. We believe the results presented in this work will contribute to the understanding of the RimP role in the ribosome assembly mechanism.

Yet Another Similarity between Mitochondrial and Bacterial Ribosomal Small Subunit Biogenesis Obtained by Structural Characterization of RbfA from S. aureus

Ribosome biogenesis is a complex and highly accurate conservative process of ribosomal subunit maturation followed by association. Subunit maturation comprises sequential stages of ribosomal RNA and proteins' folding, modification and binding, with the involvement of numerous RNAses, helicases, GTPases, chaperones, RNA, protein-modifying enzymes, and assembly factors. One such assembly factor involved in bacterial 30S subunit maturation is ribosomal binding factor A (RbfA). In this study, we present the crystal (determined at 2.2 Å resolution) and NMR structures of RbfA as well as the 2.9 Å resolution cryo-EM reconstruction of the 30S-RbfA complex from Staphylococcus aureus (S. aureus). Additionally, we show that the manner of RbfA action on the small ribosomal subunit during its maturation is shared between bacteria and mitochondria. The obtained results clarify the function of RbfA in the 30S maturation process and its role in ribosome functioning in general. Furthermore, given that S. aureus is a serious human pathogen, this study provides an additional prospect to develop antimicrobials targeting bacterial pathogens.

In vitro Reconstitution of the S. aureus 30S Ribosomal Subunit and RbfA Factor Complex for Structural Studies

Ribosome-binding factor A (RbfA) from Staphylococcus aureus is a cold adaptation protein that is required for the growth of pathogenic cells at low temperatures (10-15°C). RbfA is involved in the processing of 16S rRNA, as well as in the assembly and stabilization of the small 30S ribosomal subunit. Structural studies of the 30S-RbfA complex will help to better understand their interaction, the mechanism of such complexes, and the fundamental process such as 30S subunit assembly that determines and controls the overall level of protein biosynthesis. This article describes protocols for preparation of RbfA and the small 30S ribosomal subunits and reconstitution and optimization of the 30S-RbfA complex to obtain samples suitable for cryo-electron microscopy studies.