Biophysical reviews最新文献

In this session, six invited speakers presented their innovative research to investigate the structure and dynamics of bacterial and archaeal supramolecular assembly systems. They explained their research from the perspective of bacterial genetics, molecular biology, biochemistry, biophysics, structural biology, cell biology, microscopy imaging, and molecular dynamics simulation. The session started with a section on the mechanism of pilus assembly in cyanobacteria. It then moved on to surface architecture of a nano-sized archaeon, bacterial flagellar protein export and assembly, flagella-driven motility in bacteria and other unique assembly systems. The session highlighted significant accomplishments in the field and also presented a variety of outstanding challenges.

Synthetic biology is a broad field with a unifying theme of learning through building. At IUPAB2024 in Kyoto, Japan, five researchers gave lectures focusing on in vitro synthetic biology, where the built objects were not living cells but in vitro systems composed of biomolecules. The talks sparked lively discussions on the knowledge gained about living cells from in vitro reconstructions.

It is a great privilege for me to have been elected to the IUPAB Council earlier this year and to represent the African continent on the Council. In this short commentary, I am giving a very brief account of my academic training, biophysics research activities, and biophysics educational and outreach activities in Africa.

This commentary is a report on the 1st Next Gen. Conversation: Albany @ Ruston 2024 held on the campus of Louisiana Tech University June 11-15, 2024. The 2nd Next Gen. Conversation will be held at Louisiana Tech University June 9-13, 2026. A planning meeting will be held in June 2025 at Louisiana Tech.

This editorial for Volume 16, Issue 3 of Biophysical Reviews highlights the three-dimensional structural and dynamic information encoded in DNA sequences and introduces the topics covered in this special issue of the journal on Multiscale Simulations of DNA from Electrons to Nucleosomes. Biophysical Reviews is the official journal of the International Union for Pure and Applied Biophysics (IUPAB 2024). The international scope of the articles in the issue exemplifies the goals of IUPAB to organize worldwide advancements, co-operation, communication, and education in biophysics.

Protein-nucleic acid (PNA) binding plays critical roles in the transcription, translation, regulation, and three-dimensional organization of the genome. Structural models of proteins bound to nucleic acids (NA) provide insights into the chemical, electrostatic, and geometric properties of the protein structure that give rise to NA binding but are scarce relative to models of unbound proteins. We developed a deep learning approach for predicting PNA binding given the unbound structure of a protein that we call PNAbind. Our method utilizes graph neural networks to encode the spatial distribution of physicochemical and geometric properties of protein structures that are predictive of NA binding. Using global physicochemical encodings, our models predict the overall binding function of a protein, and using local encodings, they predict the location of individual NA binding residues. Our models can discriminate between specificity for DNA or RNA binding, and we show that predictions made on computationally derived protein structures can be used to gain mechanistic understanding of chemical and structural features that determine NA recognition. Binding site predictions were validated against benchmark datasets, achieving AUROC scores in the range of 0.92-0.95. We applied our models to the HIV-1 restriction factor APOBEC3G and showed that our model predictions are consistent with and help explain experimental RNA binding data.

Supplementary information: The online version contains supplementary material available at 10.1007/s12551-024-01201-w.

DNA carries more than the list of biochemical instructions that drive the basic functions of living systems. The sequence of base pairs includes a multitude of structural and energetic signals that determine the degree to which the long, threadlike molecule moves and how it responds to proteins and other molecules involved in its processing and packaging. The arrangements of successive base pairs in high-resolution protein-DNA crystal structures provide useful benchmarks for atomic-level simulations of double-helical DNA as well as information potentially useful in interpreting the properties of specific DNA sequences. The set of currently available structures has enough examples to characterize the conformational preferences of the DNA base-pair steps within the context of their immediate neighbors, i.e., in the context of tetramers, and reveals surprising effects of certain neighbors on local chain properties. The proteins in contact with DNA present various microenvironments that sense and/or induce the observed spatial forms. The cumulative buildup of amino-acid atoms in different protein-DNA complexes produces a binding cloud around the double helix with subtle sequence-dependent features. While the microenvironment presented by each protein to DNA is highly unique, the overall composition of amino-acid atoms within close range of DNA in a broad collection of structures is fairly uniform. The buildup of protein atoms of different types around the DNA provides new information for the improvement of nucleic acid force fields and fresh ideas for the exploration of the properties of DNA in solution.

Predicting the structure and dynamics of RNA molecules still proves challenging because of the relative scarcity of experimental RNA structures on which to train models and the very sensitive nature of RNA towards its environment. In the last decade, several atomistic force fields specifically designed for RNA have been proposed and are commonly used for simulations. However, it is not necessarily clear which force field is the most suitable for a given RNA molecule. In this contribution, we propose the use of the computational energy landscape framework to explore the energy landscape of RNA systems as it can bring complementary information to the more standard approaches of enhanced sampling simulations based on molecular dynamics. We apply the EL framework to the study of a small RNA pseudoknot, the Aquifex aeolicus tmRNA pseudoknot PK1, and we compare the results of five different RNA force fields currently available in the AMBER simulation software, in implicit solvent. With this computational approach, we can not only compare the predicted 'native' states for the different force fields, but the method enables us to study metastable states as well. As a result, our comparison not only looks at structural features of low energy folded structures, but provides insight into folding pathways and higher energy excited states, opening to the possibility of assessing the validity of force fields also based on kinetics and experiments providing information on metastable and unfolded states.

Supplementary information: The online version contains supplementary material available at 10.1007/s12551-024-01202-9.

This Editorial for Volume 16 Issue 2 first describes the issue contents before describing some upcoming events within Biophysical Reviews and concludies with an announcement on the transition of Chief Editors thanks to the outgoing Chief Editor.

Water oxidation in photosystem II (PSII) is performed by the oxygen-evolving complex Mn₄CaO₅ which can be extracted from PSII and then reconstructed using exogenous cations Mn(II) and Ca²⁺. The binding efficiency of other cations to the Mn-binding sites in Mn-depleted PSII was investigated without any positive results. At the same time, a study of the Fe cations interaction with Mn-binding sites showed that it binds at a level comparable with the binding of Mn cations. Binding of Fe(II) cations first requires its light-dependent oxidation. In general, the interaction of Fe(II) with Mn-depleted PSII has a number of features similar to the two-quantum model of photoactivation of the complex with the release of oxygen. Interestingly, incubation of Ca-depleted PSII with Fe(II) cations under certain conditions is accompanied by the formation of a chimeric cluster Mn/Fe in the oxygen-evolving complex. PSII with the cluster 2Mn2Fe was found to be capable of water oxidation, but only to the H₂O₂ intermediate. However, the cluster 3Mn1Fe can oxidize water to O₂ with an efficiency about 25% of the original in the absence of extrinsic proteins PsbQ and PsbP. In the presence of these proteins, the efficiency of O₂ evolution can reach 80% of the original when adding exogenous Ca²⁺. In this review, we summarized information on the formation of chimeric Mn-Fe clusters in the oxygen-evolving complex. The data cited may be useful for detailing the mechanism of water oxidation.