The future of integrated structural biology

NMR characterisation of the antibiotic resistance-mediating 32mer RNA from the 23S ribosomal RNA

The increasing prevalence of antibiotic resistance represents a significant public health concern, underscoring the urgent need for the development of novel therapeutic strategies. The antibiotic effects of macrolides, the second most widely used class of antibiotics, are counteracted by Erm proteins through the methylation of adenosine 2058 of the 23S ribosomal RNA (rRNA) (~ 2900 nucleotides), yielding either monomethylated or dimethylated A2058. This methylation is the molecular basis for preventing macrolides from binding and leads to the development of resistance of bacteria including Staphylococcus, Streptococcus and Enterococcus. While the function of Erm proteins have been thoroughly investigated, the role of the ribosomal RNA in acquiring antibiotic resistance is frequently underestimated, given that the ribosomal RNA is the actual target for methylation. Here, we present the comprehensive 1H, 13C and 15N NMR resonance assignment for the part of the 23S rRNA that serves as the Erm substrate in antimicrobial resistance. Furthermore, we compare the chemical shift signature of the unmethylated to the monomethylated and dimethylated RNA construct and show that changes in the RNA upon methylation are locally restricted. The resonance assignments provide a starting point for investigating and targeting the molecular mechanism of the resistance-conferring Erm proteins.

Nanosecond Hyperquenching for Electron Cryo-Microscopy Without Air-Water Interface Artifacts

A major challenge in electron cryo-microscopy (ECM) imaging is preparing the protein specimen without the artifacts caused by the surface tension at the air-water interface (AWI). Here, we report nanosecond hyperquenching (NHQ) - a method of preparing ECM samples without AWI-bound protein macromolecules. The fast narrow sample jet impinges the eutectic propane-ethane (PET) liquid cryogen at 77 K and breaks up, forming 30-150-nm-thick vitrified films. NHQ films with the protein particles are formed directly in the PET cryogen, precluding AWI tension-driven protein adsorption, preferred orientation, subunit dissociation and denaturation. The formed film surfaces are essentially specimen-free, with a 2.7-nm-thick protein depleted layer of hyperquenched glassy water (HGW). This "surface sealing" appears to be the first essential stage of vitrification at NHQ conditions; it occurs in about 35 ps on cryogen encounter. We outline the depletion mechanism, where the growing HGW layer displaces protein particles from the surface inwards the film.

Always on the Move: Overview on Chromatin Dynamics within Nuclear Processes

Our genome is organized into chromatin, a dynamic and modular structure made of nucleosomes. Chromatin organization controls access to the DNA sequence, playing a fundamental role in cell identity and function. How nucleosomes enable these processes is an active area of study. In this review, we provide an overview of chromatin dynamics, its properties, mechanisms, and functions. We highlight the diverse ways by which chromatin dynamics is controlled during transcription, DNA replication, and repair. Recent technological developments have promoted discoveries in this area, to which we provide an outlook on future research directions.

Maintaining the Integral Membrane Proteome: Revisiting the Functional Repertoire of Integral Membrane Proteases

Cells in all kingdoms of life employ dedicated protein quality control machineries for both their cytosolic and membrane proteome ensuring cellular functionality. These crucial systems consist besides a large variety of molecular chaperones, ensuring a proper fold and consequently function of the client's proteome, of several proteases to clean out damaged, unfunctional and potentially toxic proteins. One of the key features underlying the functional cycle of these quality control systems is the inherent flexibility of their bound clients which for a long time impaired detailed structural characterization, with advanced high-resolution NMR spectroscopy in the last decade playing a key role contributing to the present understanding of their functional properties. Although these studies laid the foundation of the present knowledge of the mechanistic details of the maintenance of cytosolic proteins, the understanding of related systems employed for membrane associated as well as integral membrane proteins remains rather sparse to date. Herein, we review the crucial contributions of structural and dynamical biology approaches, possessing the power to resolve both structure and dynamics of such systems as well as enabling the elucidation of the functional repertoire of multimeric proteases involved in maintaining a functional membrane proteome.

RNA structure prediction using deep learning - A comprehensive review

In computational biology, accurate RNA structure prediction offers several benefits, including facilitating a better understanding of RNA functions and RNA-based drug design. Implementing deep learning techniques for RNA structure prediction has led tremendous progress in this field, resulting in significant improvements in prediction accuracy. This comprehensive review aims to provide an overview of the diverse strategies employed in predicting RNA secondary structures, emphasizing deep learning methods. The article categorizes the discussion into three main dimensions: feature extraction methods, existing state-of-the-art learning model architectures, and prediction approaches. We present a comparative analysis of various techniques and models highlighting their strengths and weaknesses. Finally, we identify gaps in the literature, discuss current challenges, and suggest future approaches to enhance model performance and applicability in RNA structure prediction tasks. This review provides a deeper insight into the subject and paves the way for further progress in this dynamic intersection of life sciences and artificial intelligence.

On interrogating electron microscopy images to discover proteins in the cell

Interrogating individual two-dimensional (2D) cryo-EM images for the presence of defined three-dimensional (3D) structures that correspond to previously known (or predicted) macromolecular complexes is very challenging, but offers attractive opportunities for the analysis of large numbers of specimens. The work of Zhang et al. [(2025), IUCrJ, 12, 155-176] represents a significant step forward towards this goal.

Protein structure and interactions elucidated with in-cell NMR for different cell cycle phases and in 3D human tissue models

Most of our knowledge of protein structure and function originates from experiments performed with purified proteins resuspended in dilute, buffered solutions. However, most proteins function in crowded intracellular environments with complex compositions. Significant efforts have been made to develop tools to study proteins in their native cellular settings. Among these tools, in-cell NMR spectroscopy has been the sole technique for characterizing proteins in the intracellular space of living cells at atomic resolution and physiological temperature. Nevertheless, due to technological constraints, in-cell NMR studies have been limited to asynchronous single-cell suspensions, precluding obtaining information on protein behavior in different cellular states. In this study, we present a methodology that allows for obtaining an atomically resolved NMR readout of protein structure and interactions in living human cells synchronized in specific cell cycle phases and within 3D models of human tissue. The described approach opens avenues for investigating how protein structure or drug recognition responds to cell-cell communication or changes in intracellular space composition during transitions among cell cycle phases.