Human aldo-keto reductase 1C3 (AKR1C3) is a steroid modifying enzyme involved in cancer progression. Here, A-ring modified 17α-picolyl and 17(E)-picolinylidene androstane derivatives are shown to inhibit AKR1C3 activity in vitro. None of the androstane derivatives have off-target affinity for the androgen receptor, based on a fluorescence assay in yeast cells. The X-ray structure of AKR1C3 in complex with the strongest inhibitor, a 17α-picolyl androstane with a C3-oxime modification, was determined at 1.7 Å resolution. Based on this crystal structure and molecular docking, inhibition of AKR1C3 by the 17α-picolyl or 17(E)-picolinylidene derivatives depends on interactions between the C3 modification and the NADP+ cofactor, while the C17α-picolyl or C17-picolinylidene group anchors the inhibitor to AKR1C3. Because one AKR1C3 inhibitor identified here was also previously reported to inhibit CYP17, it may be possible for future researchers to design dual AKR1C3/CYP17 inhibitors based on a steroid scaffold for potential treatment of advanced prostate cancers.

• Klíčová slova
• AKR1C3, CYP17, molecular docking, prostate cancer, protein X-ray crystallography,
• MeSH
• androstany * chemie   farmakologie   chemická syntéza   MeSH
• inhibitory enzymů * farmakologie   chemie   chemická syntéza   MeSH
• krystalografie rentgenová MeSH
• lidé MeSH
• molekulární struktura MeSH
• protein AKR1C3 * antagonisté a inhibitory   metabolismus   MeSH
• simulace molekulového dockingu MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• AKR1C3 protein, human MeSH Prohlížeč
• androstany * MeSH
• inhibitory enzymů * MeSH
• protein AKR1C3 * MeSH

Influenza virus, an RNA virus of the Orthomyxoviridae family, is responsible for widespread seasonal epidemics that result in 3 to 5 million severe illnesses and more than half a million deaths annually. Given the persistent circulation of pandemic influenza variants and increasing resistance to available inhibitors, there is an urgent need for new antiviral drugs effective against various viral subtypes. Viral RNA-dependent RNA polymerase, essential for viral replication, has emerged as a promising drug target. The PA subunit with endonuclease function is especially interesting, as development of the highly potent baloxavir marboxil (Xofluza) validated its importance as a novel drug target. Flavonoids have long been studied for their anti-influenza activity but have only recently been recognized as endonuclease inhibitors. We previously identified luteolin and its glucoside derivate, orientin, as potent endonuclease inhibitors, with their binding illustrated by X-ray crystallography structures. Building on this, we employed a scaffold-hopping approach based on the luteolin structure to design structurally distinct compounds that resemble the flavonoid scaffold. Using an AlphaScreen binding assay, we identified 33 as a submicromolar PA inhibitor with low toxicity. We solved the crystal structure of the PA endonuclease-binding pseudoflavonoid 36, which has similar structure and inhibitory potency to 33. Furthermore, we identified 24, 33, 34 and 36 as inhibitors of influenza polymerase in a minireplicon luciferase reporter assay as well as inhibitors of live H1N1 virus infection in A549 human lung cells.

• Publikační typ
• časopisecké články MeSH

Photorhabdus laumondii is a well-known bacterium with a complex life cycle involving mutualism with nematodes of the genus Heterorhabditis and pathogenicity towards insect hosts. It provides an excellent model for studying the diverse roles of lectins, saccharide-binding proteins, in both symbiosis and pathogenicity. This study focuses on the seven-bladed β-propeller lectins of P. laumondii (PLLs), examining their biochemical properties (structure and saccharide specificity) and biological functions (gene expression, interactions with the nematode symbiont, and the host immune system response). Structural analyses revealed diverse oligomeric states among PLLs and a unique organisation of binding sites not described outside the PLL lectin family. Lectins exhibited high specificity for fucosylated and O-methylated saccharides with a significant avidity effect for multivalent ligands. Gene expression analysis across bacterial growth phases revealed that PLLs are predominantly expressed during the exponential phase. Interaction studies with the host immune system demonstrated that PLL5 uniquely induced melanisation in Galleria mellonella hemolymph. Furthermore, PLL2, PLL3, and PLL5 interfered with reactive oxygen species production in human blood cells, indicating their potential role in modulating host immune responses. Biofilm formation assays and binding studies with nematode life stages showed no significant involvement of PLLs in nematode colonization. Our findings highlight the primary role of PLLs in Photorhabdus pathogenicity rather than in symbiosis and offer valuable insight into the fascinating dynamics within the Photorhabdus-nematode-insect triparted system.

• Klíčová slova
• Photorhabdus, glycan array, lectin, nematode, structure-function study,
• MeSH
• bakteriální proteiny * chemie   metabolismus   genetika   MeSH
• hlístice * mikrobiologie   MeSH
• lektiny * chemie   metabolismus   genetika   MeSH
• lidé MeSH
• Photorhabdus * metabolismus   chemie   genetika   MeSH
• symbióza MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriální proteiny * MeSH
• lektiny * MeSH

Microtubule associated protein 2 (MAP2) interacts with the regulatory protein 14-3-3ζ in a cAMP-dependent protein kinase (PKA) phosphorylation dependent manner. Using selective phosphorylation, calorimetry, nuclear magnetic resonance, chemical crosslinking, and X-ray crystallography, we characterized interactions of 14-3-3ζ with various binding regions of MAP2c. Although PKA phosphorylation increases the affinity of MAP2c for 14-3-3ζ in the proline rich region and C-terminal domain, unphosphorylated MAP2c also binds the dimeric 14-3-3ζ via its microtubule binding domain and variable central domain. Monomerization of 14-3-3ζ leads to the loss of affinity for the unphosphorylated residues. In neuroblastoma cell extract, MAP2c is heavily phosphorylated by PKA and the proline kinase ERK2. Although 14-3-3ζ dimer or monomer do not interact with the residues phosphorylated by ERK2, ERK2 phosphorylation of MAP2c in the C-terminal domain reduces the binding of MAP2c to both oligomeric variants of 14-3-3ζ.

• Klíčová slova
• 14‐3‐3 proteins, extracellular signal‐regulated kinase 2, microtubule‐associated protein, nuclear magnetic resonance, protein kinase A,
• MeSH
• fosforylace MeSH
• krystalografie rentgenová MeSH
• lidé MeSH
• mitogenem aktivovaná proteinkinasa 1 metabolismus   genetika   MeSH
• molekulární modely MeSH
• multimerizace proteinu MeSH
• proteinkinasy závislé na cyklickém AMP metabolismus   genetika   MeSH
• proteiny 14-3-3 * metabolismus   chemie   genetika   MeSH
• proteiny asociované s mikrotubuly * metabolismus   chemie   genetika   MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• MAPK1 protein, human MeSH Prohlížeč
• mitogenem aktivovaná proteinkinasa 1 MeSH
• proteinkinasy závislé na cyklickém AMP MeSH
• proteiny 14-3-3 * MeSH
• proteiny asociované s mikrotubuly * MeSH
• YWHAZ protein, human MeSH Prohlížeč

The production of high-quality crystals is a key step in crystallography in general, but control of crystallization conditions is even more crucial in serial crystallography, which requires sets of crystals homogeneous in size and diffraction properties. This protocol describes the implementation of a simple and user-friendly microfluidic device that allows both the production of crystals by the counter-diffusion method and their in situ analysis by serial crystallography. As an illustration, the whole procedure is used to determine the crystal structure of three proteins from data collected at room temperature at a synchrotron radiation source.

• Klíčová slova
• CrystalChip, crystallization, microcrystals, microfluidics, serial crystallography,
• MeSH
• konformace proteinů MeSH
• krystalizace metody   přístrojové vybavení   MeSH
• krystalografie rentgenová metody   přístrojové vybavení   MeSH
• proteiny * chemie   MeSH
• teplota MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• proteiny * MeSH

The LutR protein represses the transcription of genes encoding enzymes for the utilization of l-lactate in Bacillus subtilis through binding to a specific DNA region. In this study, we employed oligonucleotide probes modified by viscosity-sensitive tetramethylated thiophene-BODIPY fluorophores to investigate the impact of selected metabolites on the LutR-DNA complex. Our goal was to identify the effector molecule whose binding alters the protein-DNA affinity, thereby enabling gene transcription. The designed DNA probes exhibited distinctive responses to the binding and release of the protein, characterized by significant alterations in fluorescence lifetime. Through this method, we have identified l-lactate as the sole metabolite exerting a substantial modulating effect on the protein-DNA interaction and thus confirmed its role as an effector molecule. Moreover, we showed that our approach was able to follow conformation changes affecting affinity, which were not captured by other methods commonly used to study the protein-DNA interaction, such as electro-mobility shift assays and florescence anisotropy binding studies. This work underlines the potential of environment-sensitive fluorophore-linked nucleotide modifications, i.e. dCTBdp, for studying the dynamics and subtle changes of protein-DNA interactions.

• Publikační typ
• časopisecké články MeSH

In mycobacteria, σA is the primary sigma factor. This essential protein binds to RNA polymerase (RNAP) and mediates transcription initiation of housekeeping genes. Our knowledge about this factor in mycobacteria is limited. Here, we performed an unbiased search for interacting partners of Mycobacterium smegmatis σA. The search revealed a number of proteins; prominent among them was MoaB2. The σA-MoaB2 interaction was validated and characterized by several approaches, revealing that it likely does not require RNAP and is specific, as alternative σ factors (e.g., closely related σB) do not interact with MoaB2. The structure of MoaB2 was solved by X-ray crystallography. By immunoprecipitation and nuclear magnetic resonance, the unique, unstructured N-terminal domain of σA was identified to play a role in the σA-MoaB2 interaction. Functional experiments then showed that MoaB2 inhibits σA-dependent (but not σB-dependent) transcription and may increase the stability of σA in the cell. We propose that MoaB2, by sequestering σA, has a potential to modulate gene expression. In summary, this study has uncovered a new binding partner of mycobacterial σA, paving the way for future investigation of this phenomenon.IMPORTANCEMycobacteria cause serious human diseases such as tuberculosis and leprosy. The mycobacterial transcription machinery is unique, containing transcription factors such as RbpA, CarD, and the RNA polymerase (RNAP) core-interacting small RNA Ms1. Here, we extend our knowledge of the mycobacterial transcription apparatus by identifying MoaB2 as an interacting partner of σA, the primary sigma factor, and characterize its effects on transcription and σA stability. This information expands our knowledge of interacting partners of subunits of mycobacterial RNAP, providing opportunities for future development of antimycobacterial compounds.

• Klíčová slova
• MoaB2, RNA polymerase, mycobacteria, transcription, σA,
• MeSH
• bakteriální proteiny * metabolismus   genetika   MeSH
• DNA řízené RNA-polymerasy metabolismus   genetika   MeSH
• genetická transkripce MeSH
• krystalografie rentgenová MeSH
• Mycobacterium smegmatis * metabolismus   genetika   MeSH
• regulace genové exprese u bakterií * MeSH
• sigma faktor * metabolismus   genetika   MeSH
• transkripční faktory * metabolismus   genetika   MeSH
• vazba proteinů * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny * MeSH
• DNA řízené RNA-polymerasy MeSH
• sigma faktor * MeSH
• transkripční faktory * MeSH

Fibroblast growth factor 2 (FGF2) is a signaling protein that plays a significant role in tissue development and repair. FGF2 binds to fibroblast growth factor receptors (FGFRs) alongside its co-factor heparin, which protects FGF2 from degradation. The binding between FGF2 and FGFRs induces intracellular signaling pathways such as RAS-MAPK, PI3K-AKT, and STAT. FGF2 has strong potential for application in cell culturing, wound healing, and cosmetics but the potential is severely limited by its low protein stability. The thermostable variant FGF2-STAB was constructed by computer-assisted protein engineering to overcome the natural limitation of FGF2. Previously reported characterization of FGF2-STAB revealed an enhanced ability to induce MAP/ERK signaling while having a lower dependence on heparin when compared with FGF2-wt. Here we report the crystal structure of FGF2-STAB solved at 1.3 Å resolution. Protein stabilization is achieved by newly formed hydrophobic interactions, polar contacts, and one additional hydrogen bond. The overall structure of FGF2-STAB is similar to FGF2-wt and does not reveal information on the experimentally observed lower dependence on heparin. A noticeable difference in flexibility in the receptor binding region can explain the differences in signaling between FGF2-STAB and its wild-type counterpart. Our structural analysis provided molecular insights into the stabilization and unique biological properties of FGF2-STAB.

• Klíčová slova
• Protein flexibility, Stabilized fibroblast growth factor 2, X-ray structural analysis,
• Publikační typ
• časopisecké články MeSH

Mycobacterial HelD is a transcription factor that recycles stalled RNAP by dissociating it from nucleic acids and, if present, from the antibiotic rifampicin. The rescued RNAP, however, must disengage from HelD to participate in subsequent rounds of transcription. The mechanism of release is unknown. We show that HelD from Mycobacterium smegmatis forms a complex with RNAP associated with the primary sigma factor σA and transcription factor RbpA but not CarD. We solve several structures of RNAP-σA-RbpA-HelD without and with promoter DNA. These snapshots capture HelD during transcription initiation, describing mechanistic aspects of HelD release from RNAP and its protective effect against rifampicin. Biochemical evidence supports these findings, defines the role of ATP binding and hydrolysis by HelD in the process, and confirms the rifampicin-protective effect of HelD. Collectively, these results show that when HelD is present during transcription initiation, the process is protected from rifampicin until the last possible moment.

• MeSH
• adenosintrifosfát metabolismus   MeSH
• bakteriální proteiny * metabolismus   genetika   MeSH
• DNA řízené RNA-polymerasy * metabolismus   MeSH
• genetická transkripce MeSH
• iniciace genetické transkripce * MeSH
• Mycobacterium smegmatis * metabolismus   genetika   MeSH
• promotorové oblasti (genetika) * MeSH
• regulace genové exprese u bakterií MeSH
• rifampin * farmakologie   MeSH
• sigma faktor * metabolismus   genetika   MeSH
• transkripční faktory metabolismus   MeSH
• vazba proteinů MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• adenosintrifosfát MeSH
• bakteriální proteiny * MeSH
• DNA řízené RNA-polymerasy * MeSH
• rifampin * MeSH
• sigma faktor * MeSH
• transkripční faktory MeSH

The SorC family of transcriptional regulators plays a crucial role in controlling the carbohydrate metabolism and quorum sensing. We employed an integrative approach combining X-ray crystallography and cryo-electron microscopy to investigate architecture and functional mechanism of two prototypical representatives of two sub-classes of the SorC family: DeoR and CggR from Bacillus subtilis. Despite possessing distinct DNA-binding domains, both proteins form similar tetrameric assemblies when bound to their respective DNA operators. Structural analysis elucidates the process by which the CggR-regulated gapA operon is derepressed through the action of two effectors: fructose-1,6-bisphosphate and newly confirmed dihydroxyacetone phosphate. Our findings provide the first comprehensive understanding of the DNA binding mechanism of the SorC-family proteins, shedding new light on their functional characteristics.

• MeSH
• Bacillus subtilis * genetika   metabolismus   MeSH
• bakteriální proteiny * chemie   metabolismus   genetika   MeSH
• DNA bakterií metabolismus   chemie   genetika   MeSH
• DNA vazebné proteiny chemie   metabolismus   genetika   MeSH
• DNA chemie   metabolismus   MeSH
• elektronová kryomikroskopie * MeSH
• fruktosadifosfáty MeSH
• krystalografie rentgenová MeSH
• molekulární modely * MeSH
• multimerizace proteinu MeSH
• operon genetika   MeSH
• regulace genové exprese u bakterií MeSH
• represorové proteiny * chemie   metabolismus   genetika   MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• bakteriální proteiny * MeSH
• DNA bakterií MeSH
• DNA vazebné proteiny MeSH
• DNA MeSH
• fructose-1,6-diphosphate MeSH Prohlížeč
• fruktosadifosfáty MeSH
• represorové proteiny * MeSH