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Bujnicki, J. M.

Publications and source records attributed to Bujnicki, J. M..

23 records · Page 2Linked to original sources

RNA fragment assembly with experimental restraints

We present RNA Masonry, a computer program and a web service for a fully automated assembly of RNA fragments into geometrically plausible models fulfilling user-provided secondary structure constraints and restraints on tertiary contacts and Small Angle X-ray Scattering (SAXS) data. We illustrate the method description with its recent application to structural studies of viral RNAs with SAXS restraints. The program web server is available at http://iimcb.genesilico.pl/rnamasonry. Contactgchojnowski@embl-hamburg.de

bioinformatics↗

AnnapuRNA: a scoring function for predicting RNA-small molecule interactions.

RNA is considered as an attractive target for new small molecule drugs. Designing active compounds can be facilitated by computational modeling. Most of the available tools developed for these prediction purposes, such as molecular docking or scoring functions, are parametrized for protein targets. The performance of these methods, when applied to RNA-ligand systems, is insufficient. To overcome these problems, we developed AnnapuRNA, a new knowledge-based scoring function designed to evaluate RNA-ligand complex structures, generated by any computational docking method. We also evaluated three main factors that may influence the structure prediction, i.e., starting conformer of a ligand, the docking program, and the scoring function used. We applied the AnnapuRNA method for a post-hoc study of the recently published structures of the FMN riboswitch. Software is available at https://github.com/filipspl/AnnapuRNA Author SummaryDrug development is a lengthy and complicated process, which requires costly experiments on a very large number of chemical compounds. The identification of chemical molecules with desired properties can be facilitated by computational methods. A number of methods were developed for computer-aided design of drugs that target protein molecules. However, recently the ribonucleic acid (RNA) emerged as an attractive target for the development of new drugs. Unfortunately, the portfolio of the computer methods that can be applied to study RNA and its interactions with small chemical molecules is very limited. This situation motivated us to develop a new computational method, with which to predict RNA-small molecule interactions. To this end, we collected the information on the statistics of interactions in experimentally determined structures of complexes formed by RNA with small molecules. We then used the statistical data to train machine learning methods aiming to distinguish between RNA-ligand interactions observed experimentally and other interactions that can be observed in theoretical analyses, but are not observed in nature. The resulting method called AnnapuRNA is superior to other similar tools and can be used to predict preferred ligands of RNA molecules and how RNA and small molecules interact with each other.

bioinformatics↗

Genome-wide mapping of therapeutically-relevant SARS-CoV-2 RNA structures

SARS-CoV-2 is a betacoronavirus with a linear single-stranded, positive-sense RNA genome of [~]30 kb, whose outbreak caused the still ongoing COVID-19 pandemic. The ability of coronaviruses to rapidly evolve, adapt, and cross species barriers makes the development of effective and durable therapeutic strategies a challenging and urgent need. As for other RNA viruses, genomic RNA structures are expected to play crucial roles in several steps of the coronavirus replication cycle. Despite this, only a handful of functionally conserved structural elements within coronavirus RNA genomes have been identified to date. Here, we performed RNA structure probing by SHAPE-MaP to obtain a single-base resolution secondary structure map of the full SARS-CoV-2 coronavirus genome. The SHAPE-MaP probing data recapitulate the previously described coronavirus RNA elements (5' UTR, ribosomal frameshifting element, and 3' UTR), and reveal new structures. Secondary structure-restrained 3D modeling of highly-structured regions across the SARS-CoV-2 genome allowed for the identification of several putative druggable pockets. Furthermore, [~]8% of the identified structure elements show significant covariation among SARS-CoV-2 and other coronaviruses, hinting at their functionally-conserved role. In addition, we identify a set of persistently single-stranded regions having high sequence conservation, suitable for the development of antisense oligonucleotide therapeutics. Collectively, our work lays the foundation for the development of innovative RNA-targeted therapeutic strategies to fight SARS-related infections.

genetics↗

RNA and DNA G-quadruplexes bind to human Dicer and inhibit its activity

Guanine (G)-rich single-stranded nucleic acids can adopt G-quadruplex structures. Accumulating evidence indicates that G-quadruplexes serve important regulatory roles in fundamental biological processes such as DNA replication, transcription, and translation, while aberrant G-quadruplex formation is linked to genome instability and cancer. Understanding the biological functions played by G-quadruplexes requires detailed knowledge of their protein interactome. Here, we report that both RNA and DNA G-quadruplexes are bound by human Dicer in vitro. Using in vitro binding assays, mutation studies, and computational modeling we demonstrate that G-quadruplexes can interact with the Platform-PAZ-Connector helix cassette of Dicer, the region responsible for anchoring microRNA precursors (pre-miRNAs). Consequently, we show that G-quadruplexes efficiently and stably inhibit the cleavage of pre-miRNA by Dicer. Our data highlight the potential of human Dicer for binding of G-quadruplexes and allow us to propose a G-quadruplex-driven sequestration mechanism of Dicer regulation.

biochemistry↗

Surface-driven RNA-refolding by the OB-fold proteins of the Trypanosoma brucei editosome

RNA editing in African trypanosomes represents an RNA-processing reaction that generates functional mitochondrial transcripts from sequence-deficient pre-mRNAs. The reaction is catalyzed by a macromolecular protein complex known as the editosome. Editosomes have been demonstrated to execute RNA-chaperone activity to overcome the highly folded nature of pre-edited substrate mRNAs. The molecular basis of this activity is unknown. Here we test five OB-fold proteins of the editosome as potential candidates. We show that the different proteins interact by hetero-oligomerization and we demonstrate that all proteins execute RNA-chaperone activity. Activity differences correlate with the surface areas of the proteins and map predominantly to the intrinsically disordered subdomains of the polypeptides. To provide a structural context for our findings we present a coarse-grained model of the editosome. The model suggests that an inner core of catalytically active editosome components is separated from an outer shell of IDP-domains that act as RNA-remodeling sites.

molecular biology↗