Structural analysis of the photosynthetic membrane from Ectothiorhodospira halochloris

1983 ◽  
Vol 41 ◽  
pp. 740-741
Author(s):  
H. Engelhardt ◽  
R. Guckenberger ◽  
W. Baumeister
Keyword(s):  
Lattice Structure ◽  
Bacterial Species ◽  
Hexagonal Lattice ◽  
Reaction Centre ◽  
Photosynthetic Membrane ◽  
Rhodopseudomonas Viridis ◽  
Photosynthetic Membranes ◽  
Ectothiorhodospira Halochloris ◽  
Main Components

Bacterial photosynthetic membranes contain, apart from lipids and electron transport components, reaction centre (RC) and light harvesting (LH) polypeptides as the main components. The RC-LH complexes in Rhodopseudomonas viridis membranes are known since quite seme time to form a hexagonal lattice structure in vivo; hence this membrane attracted the particular attention of electron microscopists. Contrary to previous claims in the literature we found, however, that 2-D periodically organized photosynthetic membranes are not a unique feature of Rhodopseudomonas viridis. At least five bacterial species, all bacteriophyll b - containing, possess membranes with the RC-LH complexes regularly arrayed. All these membranes appear to have a similar lattice structure and fine-morphology. The lattice spacings of the Ectothiorhodospira haloohloris, Ectothiorhodospira abdelmalekii and Rhodopseudomonas viridis membranes are close to 13 nm, those of Thiocapsa pfennigii and Rhodopseudomonas sulfoviridis are slightly smaller (∼12.5 nm).

The photosynthetic reaction centre from the purple bacterium Rhodopseudomonas viridis

1989 ◽  
Vol 9 (4) ◽  
pp. 383-419 ◽  
Author(s):  
Johann Deisenhofer ◽  
Harmut Michel
Keyword(s):  
Membrane Protein ◽  
Protein Crystallization ◽  
Purple Bacterium ◽  
Membrane Protein Structure ◽  
Reaction Centre ◽  
Photosynthetic Membrane ◽  
Rhodopseudomonas Viridis ◽  
Membrane Protein Complex ◽  
Membrane Protein Crystallization ◽  
Photosynthetic Reaction Centre

We first describe the history and methods of membrane protein crystallization, and show how the structure of the photosynthetic reaction centre from the purple bacterium Rhodopseudomonas viridis was solved. The structure of this membrane protein complex is correlated with its function as a light-driven electron pump across the photosynthetic membrane. Finally we draw conclusions on the structure of the photosystem II reaction centre from plants and discuss the aspects of membrane protein structure.

scholarly journals Characterization of the collagen in the hexagonal lattice of Descemet's membrane: its relation to type VIII collagen.

1990 ◽  
Vol 110 (1) ◽  
pp. 219-227 ◽  
Author(s):  
H Sawada ◽  
H Konomi ◽  
K Hirosawa
Keyword(s):  
Monoclonal Antibodies ◽  
Lattice Structure ◽  
Hexagonal Lattice ◽  
Corneal Endothelial Cells ◽  
Type Viii ◽  
Descemet's Membrane ◽  
Descemet’S Membrane

To investigate the nature of the hexagonal lattice structure in Descemet's membrane, monoclonal antibodies were raised against a homogenate of bovine Descemet's membranes. They were screened by immunofluorescence microscopy to obtain antibodies that label Descement's membrane. Some monoclonal antibodies labeled both Descemet's membrane and fine filaments within the stroma. In electron microscopy, with immunogold labeling on a critical point dried specimen, the antibodies labeled the hexagonal lattices and long-spacing structures produced by the bovine corneal endothelial cells in culture; 6A2 antibodies labeled the nodes of the lattice and 9H3 antibodies labeled the sides of the lattice. These antibodies also labeled the hexagonal lattice of Descemet's membrane in situ in ultrathin frozen sectioning. In immunofluorescence, these antibodies stained the sclera, choroid, and optic nerve sheath and its septum. They also labeled the dura mater of the spinal cord, and the perichondrium of the tracheal cartilage. In immunoblotting, the antibodies recognized 64-kD collagenous peptides both in tissue culture and in Descemet's membrane in vivo. They also recognized 50-kD pepsin-resistant fragments from Descemet's membranes that are related to type VIII collagen. However, they did not react either in immunoblotting or in immunoprecipitation with medium of subconfluent cultures from which type VIII collagen had been obtained. The results are discussed with reference to the nature of type VIII collagen, which is currently under dispute. This lattice collagen may be a member of a novel class of long-spacing fibrils.

Production of Novel Bioactive Compounds by the Bacteria Associated with Some Marine Sponges of Gulf of Mannar and Palk Bay, Southeast Coast of India

2018 ◽  
Vol 6 (8) ◽  
pp. 183
Author(s):  
V. Ramadas ◽  
G. Chandralega
Keyword(s):  
Bioactive Compounds ◽  
Bacterial Species ◽  
Marine Sponges ◽  
Marine Organisms ◽  
Gulf Of Mannar ◽  
Bacterial Symbionts ◽  
Palk Bay ◽  
Excellent Source

Sponges, exclusively are aquatic and mostly marine, are found from the deepest oceans to the edge of the sea. There are approximately 15,000 species of sponges in the world, of which, 150 occur in freshwater, but only about 17 are of commercial value. A total of 486 species of sponges have been identified in India. In the Gulf of Mannar and Palk Bay a maximum of 319 species of sponges have been recorded. It has been proved that marine organisms are excellent source of bioactive secondary metabolites and number of compounds of originated from marine organisms had been reported to possess in-vitro and in-vivo immuno stimulatory activity. Extracts from 20 sponge species were tested for bacterial symbionts and bioactive compounds were isolated from such associated bacterial species in the present study.

scholarly journals hfqPlays Important Roles in Virulence and Stress Adaptation in Cronobacter sakazakii ATCC 29544

2015 ◽  
Vol 83 (5) ◽  
pp. 2089-2098 ◽  
Author(s):  
Seongok Kim ◽  
Hyelyeon Hwang ◽  
Kwang-Pyo Kim ◽  
Hyunjin Yoon ◽  
Dong-Hyun Kang ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Soft Agar ◽  
Host Cells ◽  
Neonatal Meningitis ◽  
Animal Cells ◽  
Content Type ◽  
Flagellar Biosynthesis

Cronobacterspp. are opportunistic pathogens that cause neonatal meningitis and sepsis with high mortality in neonates. Despite the peril associated withCronobacterinfection, the mechanisms of pathogenesis are still being unraveled. Hfq, which is known as an RNA chaperone, participates in the interaction with bacterial small RNAs (sRNAs) to regulate posttranscriptionally the expression of various genes. Recent studies have demonstrated that Hfq contributes to the pathogenesis of numerous species of bacteria, and its roles are varied between bacterial species. Here, we tried to elucidate the role of Hfq inC. sakazakiivirulence. In the absence ofhfq,C. sakazakiiwas highly attenuated in disseminationin vivo, showed defects in invasion (3-fold) into animal cells and survival (103-fold) within host cells, and exhibited low resistance to hydrogen peroxide (102-fold). Remarkably, the loss ofhfqled to hypermotility on soft agar, which is contrary to what has been observed in other pathogenic bacteria. The hyperflagellated bacteria were likely to be attributable to the increased transcription of genes associated with flagellar biosynthesis in a strain lackinghfq. Together, these data strongly suggest thathfqplays important roles in the virulence ofC. sakazakiiby participating in the regulation of multiple genes.

Conformational Flexibility in Assembly of Photosynthetic Membrane Protein Complexes in vivo

2004 ◽  
Vol 10 (S02) ◽  
pp. 1496-1497
Author(s):  
P A Bullough
Keyword(s):  
Membrane Protein ◽  
Protein Complexes ◽  
Conformational Flexibility ◽  
Photosynthetic Membrane ◽  
Membrane Protein Complexes

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

scholarly journals Influence of the centrosome on the structure of nucleated microtubules.

1985 ◽  
Vol 100 (4) ◽  
pp. 1185-1191 ◽  
Author(s):  
L Evans ◽  
T Mitchison ◽  
M Kirschner
Keyword(s):  
Lattice Structure ◽  
Neuroblastoma Cells ◽  
Nucleation Sites ◽  
Self Assembled ◽  
Brain Microtubules

The capacity of the centrosome to influence the lattice structure of nucleated microtubules was studied in vitro. Brain microtubules self-assembled to give predominantly (98%) 14-protofilament microtubules. However, under exactly the same conditions of assembly they grew off of purified centrosomes from neuroblastoma cells to give mostly (82%) 13-protofilament microtubules. Thus, the nucleation sites on the centrosome constrained the microtubule lattice to yield the number of protofilaments usually found in vivo.

scholarly journals Mass Balance, Metabolite Profile, andIn Vitro-In VivoComparison of Clearance Pathways of Deleobuvir, a Hepatitis C Virus Polymerase Inhibitor

2014 ◽  
Vol 59 (1) ◽  
pp. 25-37 ◽  
Author(s):  
Lin-Zhi Chen ◽  
John P. Sabo ◽  
Elsy Philip ◽  
Lois Rowland ◽  
Yan Mao ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Mass Balance ◽  
Metabolite Profile ◽  
Fecal Samples ◽  
Acyl Glucuronide ◽  
Polymerase Inhibitor ◽  
Main Components

ABSTRACTThe pharmacokinetics, mass balance, and metabolism of deleobuvir, a hepatitis C virus (HCV) polymerase inhibitor, were assessed in healthy subjects following a single oral dose of 800 mg of [14C]deleobuvir (100 μCi). The overall recovery of radioactivity was 95.2%, with 95.1% recovered from feces. Deleobuvir had moderate to high clearance, and the half-life of deleobuvir and radioactivity in plasma were ∼3 h, indicating that there were no metabolites with half-lives significantly longer than that of the parent. The most frequently reported adverse events (in 6 of 12 subjects) were gastrointestinal disorders. Two major metabolites of deleobuvir were identified in plasma: an acyl glucuronide and an alkene reduction metabolite formed in the gastrointestinal (GI) tract by gut bacteria (CD 6168), representing ∼20% and 15% of the total drug-related material, respectively. Deleobuvir and CD 6168 were the main components in the fecal samples, each representing ∼30 to 35% of the dose. The majority of the remaining radioactivity found in the fecal samples (∼21% of the dose) was accounted for by three metabolites in which deleobuvir underwent both alkene reduction and monohydroxylation. In fresh human hepatocytes that form biliary canaliculi in sandwich cultures, the biliary excretion for these excretory metabolites was markedly higher than that for deleobuvir and CD 6168, implying that rapid biliary elimination upon hepatic formation may underlie the absence of these metabolites in circulation. The lowin vitroclearance was not predictive of the observedin vivoclearance, likely because major deleobuvir biotransformation occurred by non-CYP450-mediated enzymes that are not well represented in hepatocyte-basedin vitromodels.

scholarly journals Function-adaptive clustered nanoparticles reverse Streptococcus mutans dental biofilm and maintain microbiota balance

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Fatemeh Ostadhossein ◽  
Parikshit Moitra ◽  
Esra Altun ◽  
Debapriya Dutta ◽  
Dinabandhu Sar ◽  
...  
Keyword(s):  
Streptococcus Mutans ◽  
Ex Vivo ◽  
Bacterial Species ◽  
Reactive Oxygen Species Generation ◽  
Biofilm Inhibition ◽  
16S Rrna Analysis ◽  
Dental Biofilm ◽  
Dental Plaques

AbstractDental plaques are biofilms that cause dental caries by demineralization with acidogenic bacteria. These bacteria reside inside a protective sheath which makes any curative treatment challenging. We propose an antibiotic-free strategy to disrupt the biofilm by engineered clustered carbon dot nanoparticles that function in the acidic environment of the biofilms. In vitro and ex vivo studies on the mature biofilms of Streptococcus mutans revealed >90% biofilm inhibition associated with the contact-mediated interaction of nanoparticles with the bacterial membrane, excessive reactive oxygen species generation, and DNA fragmentation. An in vivo examination showed that these nanoparticles could effectively suppress the growth of S. mutans. Importantly, 16S rRNA analysis of the dental microbiota showed that the diversity and richness of bacterial species did not substantially change with nanoparticle treatment. Overall, this study presents a safe and effective approach to decrease the dental biofilm formation without disrupting the ecological balance of the oral cavity.

scholarly journals Signal Integration in Quorum Sensing Enables Cross-Species Induction of Virulence in Pectobacterium wasabiae

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Rita S. Valente ◽  
Pol Nadal-Jimenez ◽  
André F. P. Carvalho ◽  
Filipe J. D. Vieira ◽  
Karina B. Xavier
Keyword(s):  
Signal Transduction ◽  
Quorum Sensing ◽  
Plant Pathogen ◽  
Bacterial Species ◽  
Homoserine Lactone ◽  
Signal Molecules ◽  
Acyl Homoserine Lactone ◽  
Interspecies Interactions ◽  
Major Factors

ABSTRACT Bacterial communities can sense their neighbors, regulating group behaviors in response to cell density and environmental changes. The diversity of signaling networks in a single species has been postulated to allow custom responses to different stimuli; however, little is known about how multiple signals are integrated and the implications of this integration in different ecological contexts. In the plant pathogen Pectobacterium wasabiae (formerly Erwinia carotovora), two signaling networks—the N-acyl homoserine lactone (AHL) quorum-sensing system and the Gac/Rsm signal transduction pathway—control the expression of secreted plant cell wall-degrading enzymes, its major virulence determinants. We show that the AHL system controls the Gac/Rsm system by affecting the expression of the regulatory RNA RsmB. This regulation is mediated by ExpR2, the quorum-sensing receptor that responds to the P. wasabiae cognate AHL but also to AHLs produced by other bacterial species. As a consequence, this level of regulation allows P. wasabiae to bypass the Gac-dependent regulation of RsmB in the presence of exogenous AHLs or AHL-producing bacteria. We provide in vivo evidence that this pivotal role of RsmB in signal transduction is important for the ability of P. wasabiae to induce virulence in response to other AHL-producing bacteria in multispecies plant lesions. Our results suggest that the signaling architecture in P. wasabiae was coopted to prime the bacteria to eavesdrop on other bacteria and quickly join the efforts of other species, which are already exploiting host resources. IMPORTANCE Quorum-sensing mechanisms enable bacteria to communicate through small signal molecules and coordinate group behaviors. Often, bacteria have various quorum-sensing receptors and integrate information with other signal transduction pathways, presumably allowing them to respond to different ecological contexts. The plant pathogen Pectobacterium wasabiae has two N-acyl homoserine lactone receptors with apparently the same regulatory functions. Our work revealed that the receptor with the broadest signal specificity is also responsible for establishing the link between the main signaling pathways regulating virulence in P. wasabiae. This link is essential to provide P. wasabiae with the ability to induce virulence earlier in response to higher densities of other bacterial species. We further present in vivo evidence that this novel regulatory link enables P. wasabiae to join related bacteria in the effort to degrade host tissue in multispecies plant lesions. Our work provides support for the hypothesis that interspecies interactions are among the major factors influencing the network architectures observed in bacterial quorum-sensing pathways. IMPORTANCE Quorum-sensing mechanisms enable bacteria to communicate through small signal molecules and coordinate group behaviors. Often, bacteria have various quorum-sensing receptors and integrate information with other signal transduction pathways, presumably allowing them to respond to different ecological contexts. The plant pathogen Pectobacterium wasabiae has two N-acyl homoserine lactone receptors with apparently the same regulatory functions. Our work revealed that the receptor with the broadest signal specificity is also responsible for establishing the link between the main signaling pathways regulating virulence in P. wasabiae. This link is essential to provide P. wasabiae with the ability to induce virulence earlier in response to higher densities of other bacterial species. We further present in vivo evidence that this novel regulatory link enables P. wasabiae to join related bacteria in the effort to degrade host tissue in multispecies plant lesions. Our work provides support for the hypothesis that interspecies interactions are among the major factors influencing the network architectures observed in bacterial quorum-sensing pathways.

A novel design of wound bandage using heparin-polyvinylpyrrolidone/TiO2 nanocomposite to improved antibacterial treatment and burn wound healing effect: In vitro and in vivo evaluation

2021 ◽  
Vol 11 (11) ◽  
pp. 1808-1818
Author(s):  
Xiuli Li ◽  
Jigang Wang ◽  
Xin Li ◽  
Xiaoqian Hou ◽  
Hao Wang ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Dermal Fibroblast ◽  
Synergistic Effects ◽  
Bacterial Species ◽  
Human Dermal Fibroblast ◽  
Burn Wound ◽  
In Vivo Evaluation ◽  
Closure Rate

In our current study, porous heparin-polyvinylpyrrolidone/TiO2 nanocomposite (HpPVP/TiO2) bandage were prepared via the incorporation of TiO2 into HpPVP hydrogels for biomedical applications such as burn infection. The effect of the HpPVP hydrogels and the nanoparticles of TiO2 composition on the functional group and the surface properties of the as-fabricated bandages were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). The presence of TiO2 nanoparticles created the internal structure of the HpPVP hydrogel that aids in a homogeneous porous structure, as indicated by the scanning electron microscope (SEM). The size distribution of the TiO2 nanoparticles was measured using a transmission electron microscope (TEM). The studies on the mechanical properties of the HpPVP hydrogel indicate that the addition of TiO2 nanoparticles increases its strength. The prepared HpPVP/TiO2 nanocomposite dressing has excellent antimicrobial activity were tested against bacterial species (Staphylococcus aureus and Escherichia coli) and has good biocompatibility against human dermal fibroblast cells (HFFF2) for biological applications. In addition, in vivo evaluations in Kunming mice exposed that the as-fabricated HpPVP/TiO2 nanocomposite bandages increased the wound curing and facilitated accelerate skin cell construction along with collagen development. The synergistic effects of the HpPVP/TiO2 nanocomposite hydrogel dressing material, such as its excellent hydrophilic nature, good bactericidal activity, biocompatibility and wound closure rate through in vivo test makes it a suitable candidate for burn infections.

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