Immune surveillance involves the continual migration of antigen-scavenging immune cells from the tissues to downstream lymph nodes via lymphatic vessels. To enable such passage, cells first dock with the lymphatic entry receptor LYVE-1 on the outer surface of endothelium, using their endogenous hyaluronan glycocalyx, anchored by a second hyaluronan receptor, CD44. Why the process should require two different hyaluronan receptors and by which specific mechanism the LYVE-1•hyaluronan interaction enables lymphatic entry is however unknown. Here we describe the crystal structures and binding mechanics of murine and human LYVE-1•hyaluronan complexes. These reveal a highly unusual, sliding mode of ligand interaction, quite unlike the conventional sticking mode of CD44, in which the receptor grabs free hyaluronan chain-ends and winds them in through conformational re-arrangements in a deep binding cleft, lubricated by a layer of structured waters. Our findings explain the mode of action of a dedicated lymphatic entry receptor and define a distinct, low tack adhesive interaction that enables migrating immune cells to slide through endothelial junctions with minimal resistance, while clinging onto their hyaluronan glycocalyx for essential downstream functions.

• MeSH
• antigeny CD44 * metabolismus   MeSH
• glykokalyx metabolismus   MeSH
• krystalografie rentgenová MeSH
• kyselina hyaluronová * metabolismus   chemie   MeSH
• leukocyty metabolismus   MeSH
• lidé MeSH
• lymfatické cévy * metabolismus   MeSH
• membránové transportní proteiny metabolismus   MeSH
• myši MeSH
• vazba proteinů * MeSH
• vezikulární transportní proteiny metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antigeny CD44 * MeSH
• kyselina hyaluronová * MeSH
• LYVE1 protein, human MeSH Prohlížeč
• membránové transportní proteiny MeSH
• vezikulární transportní proteiny MeSH
• Xlkd1 protein, mouse MeSH Prohlížeč

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

Chloride Intracellular Channel (CLIC) family members uniquely transition between soluble and membrane-associated conformations. Despite decades of extensive functional and structural studies, CLICs' function as ion channels remains debated, rendering our understanding of their physiological role incomplete. Here, we expose the function of CLIC5 as a fusogen. We demonstrate that purified CLIC5 directly interacts with the membrane and induces fusion, as reflected by increased liposomal diameter and lipid and content mixing between liposomes. Moreover, we show that this activity is facilitated by acidic pH, a known trigger for CLICs' transition to a membrane-associated conformation, and that increased exposure of the hydrophobic inter-domain interface is crucial for this process. Finally, mutation of a conserved hydrophobic interfacial residue diminishes the fusogenic activity of CLIC5 in vitro and impairs excretory canal extension in C. elegans in vivo. Together, our results unravel the long-sought physiological role of these enigmatic proteins.

• MeSH
• Caenorhabditis elegans * genetika   metabolismus   MeSH
• chloridové kanály metabolismus   MeSH
• chloridy * metabolismus   MeSH
• liposomy MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• chloridové kanály MeSH
• chloridy * MeSH
• liposomy MeSH

Aldo-keto reductase 1C3 (AKR1C3) catalyzes the reduction of androstenedione to testosterone and reduces the effectiveness of chemotherapeutics. AKR1C3 is a target for treatment of breast and prostate cancer and AKR1C3 inhibition could be an effective adjuvant therapy in the context of leukemia and other cancers. In the present study, steroidal bile acid fused tetrazoles were screened for their ability to inhibit AKR1C3. Four C24 bile acids with C-ring fused tetrazoles were moderate to strong AKR1C3 inhibitors (37-88% inhibition), while B-ring fused tetrazoles had no effect on AKR1C3 activity. Based on a fluorescence assay in yeast cells, these four compounds displayed no affinity for estrogen receptor-α, or the androgen receptor, suggesting a lack of estrogenic or androgenic effects. A top inhibitor showed specificity for AKR1C3 over AKR1C2, and inhibited AKR1C3 with an IC50 of ∼7 μM. The structure of AKR1C3·NADP+ in complex with this C-ring fused bile acid tetrazole was determined by X-ray crystallography at 1.4 Å resolution, revealing that the C24 carboxylate is anchored to the catalytic oxyanion site (H117, Y55); meanwhile the tetrazole interacts with a tryptophan (W227) important for steroid recognition. Molecular docking predicts that all four top AKR1C3 inhibitors bind with nearly identical geometry, suggesting that C-ring bile acid fused tetrazoles represent a new class of AKR1C3 inhibitors.

• Publikační typ
• časopisecké články MeSH

Rel stringent factors are bifunctional ribosome-associated enzymes that catalyze both synthesis and hydrolysis of the alarmones (p)ppGpp. Besides the allosteric control by starved ribosomes and (p)ppGpp, Rel is regulated by various protein factors depending on specific stress conditions, including the c-di-AMP-binding protein DarB. However, how these effector proteins control Rel remains unknown. We have determined the crystal structure of the DarB2:RelNTD2 complex, uncovering that DarB directly engages the SYNTH domain of Rel to stimulate (p)ppGpp synthesis. This association with DarB promotes a SYNTH-primed conformation of the N-terminal domain region, markedly increasing the affinity of Rel for ATP while switching off the hydrolase activity of the enzyme. Binding to c-di-AMP rigidifies DarB, imposing an entropic penalty that precludes DarB-mediated control of Rel during normal growth. Our experiments provide the basis for understanding a previously unknown mechanism of allosteric regulation of Rel stringent factors independent of amino acid starvation.

• Publikační typ
• časopisecké články MeSH

The programmable synthesis of rationally engineered crystal architectures for the precise arrangement of molecular species is a foundational goal in nanotechnology, and DNA has become one of the most prominent molecules for the construction of these materials. In particular, branched DNA junctions have been used as the central building block for the assembly of 3D lattices. Here, crystallography is used to probe the effect of all 36 immobile Holliday junction sequences on self-assembling DNA crystals. Contrary to the established paradigm in the field, most junctions yield crystals, with some enhancing the resolution or resulting in unique crystal symmetries. Unexpectedly, even the sequence adjacent to the junction has a significant effect on the crystal assemblies. Six of the immobile junction sequences are completely resistant to crystallization and thus deemed "fatal," and molecular dynamics simulations reveal that these junctions invariably lack two discrete ion binding sites that are pivotal for crystal formation. The structures and dynamics detailed here could be used to inform future designs of both crystals and DNA nanostructures more broadly, and have potential implications for the molecular engineering of applied nanoelectronics, nanophotonics, and catalysis within the crystalline context.

• MeSH
• DNA chemie   MeSH
• konformace nukleové kyseliny MeSH
• křížová struktura DNA * genetika   MeSH
• krystalizace MeSH
• nanostruktury * chemie   MeSH
• nanotechnologie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• DNA MeSH
• křížová struktura DNA * MeSH

Influenza neuraminidase is responsible for the escape of new viral particles from the infected cell surface. Several neuraminidase inhibitors are used clinically to treat patients or stockpiled for emergencies. However, the increasing development of viral resistance against approved inhibitors has underscored the need for the development of new antivirals effective against resistant influenza strains. A facile, sensitive, and inexpensive screening method would help achieve this goal. Recently, we described a multiwell plate-based DNA-linked inhibitor antibody assay (DIANA). This highly sensitive method can quantify femtomolar concentrations of enzymes. DIANA also has been applied to high-throughput enzyme inhibitor screening, allowing the evaluation of inhibition constants from a single inhibitor concentration. Here, we report the design, synthesis, and structural characterization of a tamiphosphor derivative linked to a reporter DNA oligonucleotide for the development of a DIANA-type assay to screen potential influenza neuraminidase inhibitors. The neuraminidase is first captured by an immobilized antibody, and the test compound competes for binding to the enzyme with the oligo-linked detection probe, which is then quantified by qPCR. We validated this novel assay by comparing it with the standard fluorometric assay and demonstrated its usefulness for sensitive neuraminidase detection as well as high-throughput screening of potential new neuraminidase inhibitors.

• Klíčová slova
• DIANA, assay, crystallography, influenza neuraminidase,
• MeSH
• antivirové látky chemie   farmakologie   MeSH
• chřipka lidská farmakoterapie   enzymologie   virologie   MeSH
• DNA chemie   MeSH
• inhibitory enzymů chemie   farmakologie   MeSH
• kyseliny fosforité chemie   MeSH
• lidé MeSH
• neuraminidasa antagonisté a inhibitory   metabolismus   MeSH
• oseltamivir analogy a deriváty   chemie   MeSH
• preklinické hodnocení léčiv metody   MeSH
• reprodukovatelnost výsledků MeSH
• virové proteiny antagonisté a inhibitory   metabolismus   MeSH
• virus chřipky A účinky léků   enzymologie   fyziologie   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antivirové látky MeSH
• DNA MeSH
• inhibitory enzymů MeSH
• kyseliny fosforité MeSH
• neuraminidasa MeSH
• oseltamivir MeSH
• tamiphosphor MeSH Prohlížeč
• virové proteiny MeSH

Neuraminidase is the main target for current influenza drugs. Reduced susceptibility to oseltamivir, the most widely prescribed neuraminidase inhibitor, has been repeatedly reported. The resistance substitutions I223V and S247N, alone or in combination with the major oseltamivir-resistance mutation H275Y, have been observed in 2009 pandemic H1N1 viruses. We overexpressed and purified the ectodomain of wild-type neuraminidase from the A/California/07/2009 (H1N1) influenza virus, as well as variants containing H275Y, I223V, and S247N single mutations and H275Y/I223V and H275Y/S247N double mutations. We performed enzymological and thermodynamic analyses and structurally examined the resistance mechanism. Our results reveal that the I223V or S247N substitution alone confers only a moderate reduction in oseltamivir affinity. In contrast, the major oseltamivir resistance mutation H275Y causes a significant decrease in the enzyme’s ability to bind this drug. Combination of H275Y with an I223V or S247N mutation results in extreme impairment of oseltamivir’s inhibition potency. Our structural analyses revealed that the H275Y substitution has a major effect on the oseltamivir binding pose within the active site while the influence of other studied mutations is much less prominent. Our crystal structures also helped explain the augmenting effect on resistance of combining H275Y with both substitutions.

• Klíčová slova
• crystal structure, influenza neuraminidase, isothermal titration calorimetry, oseltamivir, resistance,
• MeSH
• antivirové látky farmakologie   MeSH
• chřipka lidská virologie   MeSH
• inhibitory enzymů farmakologie   MeSH
• kalorimetrie MeSH
• kinetika MeSH
• krystalizace MeSH
• lidé MeSH
• missense mutace MeSH
• neuraminidasa chemie   genetika   MeSH
• oseltamivir farmakologie   MeSH
• replikace viru MeSH
• substituce aminokyselin MeSH
• termodynamika MeSH
• virová léková rezistence genetika   MeSH
• virové proteiny chemie   genetika   MeSH
• virus chřipky A, podtyp H1N1 účinky léků   enzymologie   genetika   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antivirové látky MeSH
• inhibitory enzymů MeSH
• neuraminidasa MeSH
• oseltamivir MeSH
• virové proteiny MeSH

Human insulin is a pivotal protein hormone controlling metabolism, growth, and aging and whose malfunctioning underlies diabetes, some cancers, and neurodegeneration. Despite its central position in human physiology, the in vivo oligomeric state and conformation of insulin in its storage granules in the pancreas are not known. In contrast, many in vitro structures of hexamers of this hormone are available and fall into three conformational states: T6, T3Rf3, and R6 As there is strong evidence for accumulation of neurotransmitters, such as serotonin and dopamine, in insulin storage granules in pancreatic β-cells, we probed by molecular dynamics (MD) and protein crystallography (PC) if these endogenous ligands affect and stabilize insulin oligomers. Parallel studies independently converged on the observation that serotonin binds well within the insulin hexamer (site I), stabilizing it in the T3R3 conformation. Both methods indicated serotonin binding on the hexamer surface (site III) as well. MD, but not PC, indicated that dopamine was also a good site III ligand. Some of the PC studies also included arginine, which may be abundant in insulin granules upon processing of pro-insulin, and stable T3R3 hexamers loaded with both serotonin and arginine were obtained. The MD and PC results were supported further by in solution spectroscopic studies with R-state-specific chromophore. Our results indicate that the T3R3 oligomer is a plausible insulin pancreatic storage form, resulting from its complex interplay with neurotransmitters, and pro-insulin processing products. These findings may have implications for clinical insulin formulations.

• Klíčová slova
• crystal structure, dopamine, insulin, pancreatic islet, serotonin, vesicles,
• MeSH
• beta-buňky * chemie   metabolismus   MeSH
• biologické modely * MeSH
• inzulin * chemie   metabolismus   MeSH
• lidé MeSH
• multimerizace proteinu * MeSH
• neurotransmiterové látky metabolismus   MeSH
• počítačová simulace * MeSH
• sekreční vezikuly * chemie   metabolismus   MeSH
• serotonin metabolismus   MeSH
• simulace molekulární dynamiky MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• inzulin * MeSH
• neurotransmiterové látky MeSH
• serotonin MeSH

UNLABELLED: In order to initiate an infection, viruses need to deliver their genomes into cells. This involves uncoating the genome and transporting it to the cytoplasm. The process of genome delivery is not well understood for nonenveloped viruses. We address this gap in our current knowledge by studying the uncoating of the nonenveloped human cardiovirus Saffold virus 3 (SAFV-3) of the family Picornaviridae SAFVs cause diseases ranging from gastrointestinal disorders to meningitis. We present a structure of a native SAFV-3 virion determined to 2.5 Å by X-ray crystallography and an 11-Å-resolution cryo-electron microscopy reconstruction of an "altered" particle that is primed for genome release. The altered particles are expanded relative to the native virus and contain pores in the capsid that might serve as channels for the release of VP4 subunits, N termini of VP1, and the RNA genome. Unlike in the related enteroviruses, pores in SAFV-3 are located roughly between the icosahedral 3- and 5-fold axes at an interface formed by two VP1 and one VP3 subunit. Furthermore, in native conditions many cardioviruses contain a disulfide bond formed by cysteines that are separated by just one residue. The disulfide bond is located in a surface loop of VP3. We determined the structure of the SAFV-3 virion in which the disulfide bonds are reduced. Disruption of the bond had minimal effect on the structure of the loop, but it increased the stability and decreased the infectivity of the virus. Therefore, compounds specifically disrupting or binding to the disulfide bond might limit SAFV infection. IMPORTANCE: A capsid assembled from viral proteins protects the virus genome during transmission from one cell to another. However, when a virus enters a cell the virus genome has to be released from the capsid in order to initiate infection. This process is not well understood for nonenveloped viruses. We address this gap in our current knowledge by studying the genome release of Human Saffold virus 3 Saffold viruses cause diseases ranging from gastrointestinal disorders to meningitis. We show that before the genome is released, the Saffold virus 3 particle expands, and holes form in the previously compact capsid. These holes serve as channels for the release of the genome and small capsid proteins VP4 that in related enteroviruses facilitate subsequent transport of the virus genome into the cell cytoplasm.

• MeSH
• Cardiovirus chemie   fyziologie   ultrastruktura   MeSH
• elektronová kryomikroskopie MeSH
• HeLa buňky MeSH
• krystalografie rentgenová MeSH
• lidé MeSH
• počítačové zpracování obrazu MeSH
• svlékání virového obalu * MeSH
• virové struktury * MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH