scholarly journals Electron cryo-microscopy of Bacteriophage PR772 reveals the composition and structure of the elusive vertex complex and the capsid architecture

2019 ◽  
Author(s):  
Hemanth. K. N. Reddy ◽  
Janos Hajdu ◽  
Marta Carroni ◽  
Martin Svenda
Keyword(s):  
Lipid Membrane ◽  
3D Structure ◽  
Vital Role ◽  
Host Recognition ◽  
Protein Conformations ◽  
Wild Type ◽  
Composition And Structure ◽  
Recognition Protein ◽  
New Protein ◽  
Wild Type Virion

AbstractBacteriophage PR772, a member of theTectiviridaefamily, has a 70-nm diameter icosahedral protein capsid that encapsulates a lipid membrane, dsDNA, and various internal proteins. An icosahedrally averaged CryoEM reconstruction of the wild-type virion and a localized reconstruction of the vertex region reveals the composition and the structure of the vertex complex along with new protein conformations that play a vital role in maintaining the capsid architecture of the virion. The overall resolution of the virion is 2.75 Å, while the resolution of the protein capsid is 2.3 Å. The conventional penta-symmetron formed by the capsomeres is replaced by a large vertex complex in the pseudo T=25 capsid. All the vertices contain the host-recognition protein, P5; two of these vertices show the presence of the receptor-binding protein, P2. The 3D structure of the vertex complex shows interactions with the viral membrane, indicating a possible mechanism for viral infection.

scholarly journals Electron cryo-microscopy of bacteriophage PR772 reveals the elusive vertex complex and the capsid architecture

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Hemanth KN Reddy ◽  
Marta Carroni ◽  
Janos Hajdu ◽  
Martin Svenda
Keyword(s):  
Lipid Membrane ◽  
3D Structure ◽  
Vital Role ◽  
Host Recognition ◽  
Protein Conformations ◽  
Wild Type ◽  
Viral Membrane ◽  
Recognition Protein ◽  
New Protein ◽  
Wild Type Virion

Bacteriophage PR772, a member of the Tectiviridae family, has a 70 nm diameter icosahedral protein capsid that encapsulates a lipid membrane, dsDNA, and various internal proteins. An icosahedrally averaged CryoEM reconstruction of the wild-type virion and a localized reconstruction of the vertex region reveal the composition and the structure of the vertex complex along with new protein conformations that play a vital role in maintaining the capsid architecture of the virion. The overall resolution of the virion is 2.75 Å, while the resolution of the protein capsid is 2.3 Å. The conventional penta-symmetron formed by the capsomeres is replaced by a large vertex complex in the pseudo T = 25 capsid. All the vertices contain the host-recognition protein, P5; two of these vertices show the presence of the receptor-binding protein, P2. The 3D structure of the vertex complex shows interactions with the viral membrane, indicating a possible mechanism for viral infection.

Streblus asper Lour. exerts MAPK and SKN-1 mediated anti-aging, anti-photoaging activities and imparts neuroprotection by ameliorating Aβ in Caenorhabditis elegans

2021 ◽  
pp. 1-17
Author(s):  
Mani Iyer Prasanth ◽  
James Michael Brimson ◽  
Dicson Sheeja Malar ◽  
Anchalee Prasansuklab ◽  
Tewin Tencomnao
Keyword(s):  
Oxidative Stress ◽  
Caenorhabditis Elegans ◽  
Stress Resistance ◽  
Vital Role ◽  
Transgenic Strain ◽  
Wild Type ◽  
Neuroprotective Effects ◽  
C Elegans ◽  
Streblus Asper

BACKGROUND: Streblus asper Lour., has been reported to have anti-aging and neuroprotective efficacies in vitro. OBJECTIVE: To analyze the anti-aging, anti-photoaging and neuroprotective efficacies of S. asper in Caenorhabditis elegans. METHODS: C. elegans (wild type and gene specific mutants) were treated with S. asper extract and analyzed for lifespan and other health benefits through physiological assays, fluorescence microscopy, qPCR and Western blot. RESULTS: The plant extract was found to increase the lifespan, reduce the accumulation of lipofuscin and modulate the expression of candidate genes. It could extend the lifespan of both daf-16 and daf-2 mutants whereas the pmk-1 mutant showed no effect. The activation of skn-1 was observed in skn-1::GFP transgenic strain and in qPCR expression. Further, the extract can extend the lifespan of UV-A exposed nematodes along with reducing ROS levels. Additionally, the extract also extends lifespan and reduces paralysis in Aβ transgenic strain, apart from reducing Aβ expression. CONCLUSIONS: S. asper was able to extend the lifespan and healthspan of C. elegans which was independent of DAF-16 pathway but dependent on SKN-1 and MAPK which could play a vital role in eliciting the anti-aging, anti-photoaging and neuroprotective effects, as the extract could impart oxidative stress resistance and neuroprotection.

scholarly journals Modulation of HIF-2α PAS-B domain contributes to physiological responses

2018 ◽  
Vol 115 (52) ◽  
pp. 13240-13245 ◽  
Author(s):  
Zhihui Feng ◽  
Xuan Zou ◽  
Yaomin Chen ◽  
Hanzhi Wang ◽  
Yingli Duan ◽  
...  
Keyword(s):  
Body Weight ◽  
Metabolic Regulation ◽  
Body Weight Gain ◽  
Metabolic Stress ◽  
Vital Role ◽  
Mutant Mice ◽  
Single Mutation ◽  
Wild Type ◽  
Adipose Mass

Hypoxia-inducible factors (HIFs) are transcription factors in the basic helix–loop–helix PER-ARNT-SIM (bHLH-PAS) protein family that contain internal hydrophobic cavities within their PAS-A and PAS-B domains. Among HIFs, the HIF-2α PAS-B domain contains a relatively large cavity exploited for the development of specific artificial ligands such as PT2399. Administration of PT2399 could suppress HIF-2α target gene expression without affecting HIF-1 activity in mice under hypoxia conditions. A single mutation (S305M) within the HIF-2α PAS-B domain suppressed HIF-2α activity while conferring resistance to PT2399 in vivo, indicating the vital role of PAS-B domain in HIF-2α hypoxia response. In contrast, the mutant mice did not phenocopy PT2399 intervention in wild-type mice under metabolic stress. Under a high-fat diet (HFD), the mutant mice exert enhanced adipogenesis and obtain larger adipose mass and body weight gain compared to wild type. However, administration of PT2399 along with HFD feeding sufficiently suppressed HFD-induced body weight and adipose mass increase through suppression of adipogenesis and lipogenesis. The accompanying decreased lipid accumulation in the liver and improved glucose tolerance in wild-type mice were not observed in the mutant mice indicating negative regulation of HIF-2α on obesity and a complex role for the PAS-B domain in metabolic regulation. Notably, short-term administration of PT2399 to obese mice decreased adipose mass and improved metabolic condition. These results indicate a regulatory role for HIF-2α in obesity progression and suggest a therapeutic opportunity for PT2399 in obesity and associated metabolic disorders.

scholarly journals Seipin traps triacylglycerols to facilitate their nanoscale clustering in the ER membrane

2020 ◽  
Author(s):  
Xavier Prasanna ◽  
Veijo T. Salo ◽  
Shiqian Li ◽  
Katharina Ven ◽  
Helena Vihinen ◽  
...  
Keyword(s):  
Lipid Droplet ◽  
In Silico ◽  
Lipid Membrane ◽  
Wild Type ◽  
Binding Interface ◽  
Biomolecular Simulations ◽  
Hydrophobic Helices ◽  
Tag Clustering ◽  
Er Membrane ◽  
In Cells

AbstractSeipin is a disk-like oligomeric ER protein important for lipid droplet (LD) biogenesis and triacylglycerol (TAG) delivery to growing LDs. Here we show through biomolecular simulations bridged to experiments that seipin can trap TAGs in the ER bilayer via the luminal hydrophobic helices of the protomers delineating the inner opening of the seipin disk. This promotes the nanoscale sequestration of TAGs at a concentration that by itself is insufficient to induce TAG clustering in a lipid membrane. We identify Ser166 in the α3 helix as a favored TAG occupancy site and show that mutating it compromises the ability of seipin complexes to sequester TAG in silico and to promote TAG transfer to LDs in cells. While seipin-S166D mutant colocalizes poorly with promethin, the association of nascent wild-type seipin complexes with promethin is promoted by TAGs. Together, these results suggest that seipin traps TAGs via its luminal hydrophobic helices, serving as a catalyst for seeding the TAG cluster from dissolved monomers inside the seipin ring, thereby generating a favorable promethin binding interface.

scholarly journals Neuroprotective effect of ZnT3 knockout on subarachnoid hemorrhage

2018 ◽  
Vol 9 (1) ◽  
pp. 26-32
Author(s):  
Duo Chen ◽  
Zhao-Bo Nie ◽  
Zhi-Hong Chi ◽  
Zhan-You Wang ◽  
Xiang-Tai Wei ◽  
...  
Keyword(s):  
Subarachnoid Hemorrhage ◽  
Neuroprotective Effect ◽  
Neuronal Injury ◽  
Early Brain Injury ◽  
Vital Role ◽  
Tunel Staining ◽  
Wild Type ◽  
Potential Therapeutic Target ◽  
Neurological Score ◽  
Hematoxylin Eosin

Abstract Background The pathophysiology of early brain injury (EBI) after subarachnoid hemorrhage (SAH) is poorly understood. The present study evaluates the influence of zinc transporter 3 (ZnT3) knockout and the depletion of vesicular zinc on EBI. Methodology SAH was induced in ZnT3 KO mice by internal carotid artery perforation. The changes in behavior were recorded at 24 hours after SAH. Hematoxylin-eosin, Nissl and TUNEL staining were performed to evaluate neuronal apoptosis. Data from mice with a score of 8-12 in intracerebral bleeding (i.e. moderate SAH), were analyzed. Results The degree of SAH-induced neuronal injury was directly correlated to the amount of blood lost, which in turn was negatively reflected in their behavior. The Wild Type (WT)-SAH group behaved poorly when compared to the knockout (KO)-SAH mice and their poor neurological score was accompanied by an increase in the number of apoptotic neurons. Conversely, the improvement of behavior in the KO-SAH group was associated with a marked reduction in apoptotic neurons. Conclusions These results suggest that ZnT3 knockout may have played a vital role in the attenuation of neuronal injury after SAH and that ZnT3 may prove to be a potential therapeutic target for neuroprotection in EBI.

scholarly journals TFIIB/SUA7(E202G) is an allele-specific suppressor of TBP1(E186D)

2007 ◽  
Vol 406 (2) ◽  
pp. 265-271 ◽  
Author(s):  
Boon Shang Chew ◽  
Norbert Lehming
Keyword(s):  
Temperature Sensitivity ◽  
Slow Growth ◽  
Vital Role ◽  
Rrna Genes ◽  
Limiting Factor ◽  
Wild Type ◽  
Transcription Factor Iib ◽  
Allele Specific ◽  
Tata Box Binding Protein ◽  
Polymerase I

The TBP (TATA-box-binding protein), Tbp1p, plays a vital role in all three classes of transcription by RNA polymerases I–III. A TBP1(E186D) mutation had been described that affected interaction of Tbp1p with TFIIB (transcription factor IIB) and that caused slow-growth, temperature-sensitivity, 3-aminotriazole-sensitivity as well as a gal− phenotype. We used the TBP1(E186D) mutant for suppressor screens, and we isolated TFIIB/SUA7(E202G) as an allele-specific suppressor of all phenotypes caused by the TBP1(E186D) mutation. Our results show that the SUA7(E202G) mutation restored binding of TFIIB to Tbp1(E186D)p. In addition, we observed that Tbp1(E186D)p was expressed at a lower level than wild-type Tbp1p, and that SUA7(E202G) restored the protein level of Tbp1(E186D)p. This suggested that the TBP1(E186D) mutation might have generated its phenotypes by making Tbp1p the limiting factor for activated transcription. DNA microarray analysis indicated that the TBP1(E186D) temperature-sensitivity and slow-growth phenotypes might have been caused by insufficient amounts of Tbp1p for efficient transcription of the rRNA genes by RNA polymerase I.

scholarly journals Candida albicans sphingolipid C9-methyltransferase is involved in hyphal elongation

Microbiology ◽  
2010 ◽  
Vol 156 (4) ◽  
pp. 1234-1243 ◽  
Author(s):  
Takahiro Oura ◽  
Susumu Kajiwara
Keyword(s):  
Candida Albicans ◽  
Lipid Membrane ◽  
Hyphal Growth ◽  
Pathogenic Fungi ◽  
Wild Type ◽  
Membrane Structures ◽  
Pathogenic Yeast ◽  
Chain Base ◽  
Long Chain Base ◽  
Long Chain

C9-methylated glucosylceramide is a fungus-specific sphingolipid. This lipid is a major membrane component in the cell and is thought to play important roles in the growth and virulence of several fungal species. To investigate the importance of the methyl branch of the long-chain base in glucosylceramides in pathogenic fungi, we identified and characterized a sphingolipid C9-methyltransferase gene (MTS1, C9-MethylTransferase for Sphingolipid 1) in the pathogenic yeast Candida albicans. The mts1 disruptant lacked (E,E)-9-methylsphinga-4,8-dienine in its glucosylceramides and contained (E)-sphing-4-enine and (E,E)-sphinga-4,8-dienine. Reintroducing the MTS1 gene into the mts1 disruptant restored the synthesis of (E,E)-9-methylsphinga-4,8-dienine in the glucosylceramides. We also created a disruptant of the HSX11 gene, encoding glucosylceramide synthase, which catalyses the final step of glucosylceramide synthesis, in C. albicans and compared this mutant with the mts1 disruptant. The C. albicans mts1 and hsx11 disruptants both had a decreased hyphal growth rate compared to the wild-type strain. The hsx11 disruptant showed increased susceptibility to SDS and fluconazole, similar to a previously reported sld1 disruptant that contained only (E)-sphing-4-enine in its glucosylceramides, suggesting that these strains have defects in their cell membrane structures. In contrast, the mts1 disruptant grew similarly to wild-type in medium containing SDS or fluconazole. These results suggest that the C9-methyl group of a long-chain base in glucosylceramides plays an important role in the hyphal elongation of C. albicans independent of lipid membrane disruption.

scholarly journals ProBLM Web Server: Protein and Membrane Placement and Orientation Package

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Taylor Kimmett ◽  
Nicholas Smith ◽  
Shawn Witham ◽  
Marharyta Petukh ◽  
Subhra Sarkar ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Lipid Bilayer ◽  
Lipid Membrane ◽  
3D Structure ◽  
Web Server ◽  
Bilayer Lipid Membrane ◽  
Lipid Bilayer Membranes ◽  
Heavy Atoms ◽  
Membrane Complex ◽  
Position And Orientation

The 3D structures of membrane proteins are typically determined without the presence of a lipid bilayer. For the purpose of studying the role of membranes on the wild type characteristics of the corresponding protein, determining the position and orientation of transmembrane proteins within a membrane environment is highly desirable. Here we report a geometry-based approach to automatically insert a membrane protein with a known 3D structure into pregenerated lipid bilayer membranes with various dimensions and lipid compositions or into a pseudomembrane. The pseudomembrane is built using the Protein Nano-Object Integrator which generates a parallelepiped of user-specified dimensions made up of pseudoatoms. The pseudomembrane allows for modeling the desolvation effects while avoiding plausible errors associated with wrongly assigned protein-lipid contacts. The method is implemented into a web server, the ProBLM server, which is freely available to the biophysical community. The web server allows the user to upload a protein coordinate file and any missing residues or heavy atoms are regenerated. ProBLM then creates a combined protein-membrane complex from the given membrane protein and bilayer lipid membrane or pseudomembrane. The user is given an option to manually refine the model by manipulating the position and orientation of the protein with respect to the membrane.

scholarly journals Characterization of a potent human interleukin-11 agonist

2003 ◽  
Vol 375 (1) ◽  
pp. 23-32 ◽  
Author(s):  
Dimitri HARMEGNIES ◽  
Xiao-Ming WANG ◽  
Paul VANDENBUSSCHE ◽  
Arnaud LEON ◽  
Patricia VUSIO ◽  
...  
Keyword(s):  
Biological Activities ◽  
Gel Filtration ◽  
Electrophoretic Analysis ◽  
Receptor Complex ◽  
Wild Type ◽  
Α Subunit ◽  
Receptor Chain ◽  
Interleukin 11 ◽  
New Protein

Human interleukin-11 (hIL-11) is a multi-potential cytokine that is involved in numerous biological activities, such as haematopoiesis, osteoclastogenesis, neurogenesis and female fertility, and also displays anti-inflammatory properties. IL-11 is used clinically to treat chemotherapy-induced thrombocytopenia. Because of its broad spectrum of action, improved IL-11 agonists, as well as IL-11 antagonists, could be of interest for numerous clinical applications. IL-11 signalling is dependent on the formation of a tripartite ligand–receptor complex consisting of IL-11, the IL-11R (IL-11 receptor) α subunit (responsible for the specificity of the interaction) and gp130 (glycoprotein 130) receptor β subunit (responsible for signal transduction). The interaction between IL-11 and IL-11Rα subunit occurs at its recently assigned site I. We have designed an IL-11 mutein whose hydrophobicity at site I has been increased. The mutein has been characterized in terms of structure, affinity, specificity and bioactivity. Electrophoretic analysis, gel filtration, IR spectroscopy and CD indicate that this new protein is more compact than wild-type IL-11. It binds to IL-11Rα with a three-fold-enhanced affinity, and retains the ability to recruit gp130 through site II. However, analysis of its biological activity revealed a complex pattern: although this mutein is 60–400-fold more active than wild-type IL-11 on the proliferation of 7TD1 murine hybridoma cell, it is less active than IL-11 on the proliferation of B9 cells, another murine hybridoma cell line. The results are interpreted on the basis of an IL-11 conformational change induced by the mutations, and the preferential use by the mutein of another unknown transducing receptor chain.

scholarly journals PPARαas a Transcriptional Regulator for Detoxification of Plant Diet-Derived Unfavorable Compounds

PPAR Research ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Bunichiro Ashibe ◽  
Yu Nakajima ◽  
Yuka Fukui ◽  
Kiyoto Motojima
Keyword(s):  
Nuclear Receptors ◽  
Transcriptional Regulator ◽  
Vital Role ◽  
Detoxification Enzymes ◽  
Natural Food ◽  
Unexpected Result ◽  
Wild Type ◽  
Toxic Compounds ◽  
Plant Seeds ◽  
Indirect Activation

Plants contain potentially toxic compounds for animals and animals have developed physiological strategies to detoxify the ingested toxins during evolution. Feeding mice with various plant seeds and grains showed unexpected result that only sesame killed PPARα-null mice but not wild-type mice at all. A detailed analysis of this observation revealed that PPARαis involved in the metabolism of toxic compounds from plants as well as endobiotic substrates by inducing phase I and phase II detoxification enzymes. PPARαplays a vital role in direct or indirect activation of the relevant genes via the complex network among other xenobiotic nuclear receptors. Thus, PPARαplays its wider and more extensive role in energy metabolism from natural food intake to fat storage than previously thought.

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