scholarly journals Cytochrome bd -Dependent Bioenergetics and Antinitrosative Defenses in Salmonella Pathogenesis

mBio ◽  
2016 ◽  
Vol 7 (6) ◽  
Author(s):  
Jessica Jones-Carson ◽  
Maroof Husain ◽  
Lin Liu ◽  
David J. Orlicky ◽  
Andrés Vázquez-Torres
Keyword(s):  
Nitrosative Stress ◽  
Great Part ◽  
Bacterial Pathogen ◽  
Electron Acceptors ◽  
Tissue Hypoxia ◽  
Dual Function ◽  
Bacterial Cells ◽  
High Affinity ◽  
Electron Transport Chains ◽  
Quinol Oxidases

ABSTRACT In the course of an infection, Salmonella enterica occupies diverse anatomical sites with various concentrations of oxygen (O 2 ) and nitric oxide (NO). These diatomic gases compete for binding to catalytic metal groups of quinol oxidases. Enterobacteriaceae express two evolutionarily distinct classes of quinol oxidases that differ in affinity for O 2 and NO as well as stoichiometry of H + translocated across the cytoplasmic membrane. The investigations presented here show that the dual function of bacterial cytochrome bd in bioenergetics and antinitrosative defense enhances Salmonella virulence. The high affinity of cytochrome bd for O 2 optimizes respiratory rates in hypoxic cultures, and thus, this quinol oxidase maximizes bacterial growth under O 2 -limiting conditions. Our investigations also indicate that cytochrome bd , rather than cytochrome bo , is an intrinsic component of the adaptive antinitrosative toolbox of Salmonella . Accordingly, induction of cytochrome bd helps Salmonella grow and respire in the presence of inhibitory NO. The combined antinitrosative defenses of cytochrome bd and the flavohemoglobin Hmp account for a great part of the adaptations that help Salmonella recover from the antimicrobial activity of NO. Moreover, the antinitrosative defenses of cytochrome bd and flavohemoglobin Hmp synergize to promote Salmonella growth in systemic tissues. Collectively, our investigations indicate that cytochrome bd is a critical means by which Salmonella resists the nitrosative stress that is engendered in the innate response of mammalian hosts while it concomitantly allows for proper O 2 utilization in tissue hypoxia. IMPORTANCE It is becoming quite apparent that metabolism is critically important to the virulence potential of pathogenic microorganisms. Bacterial cells use a variety of terminal electron acceptors to power electron transport chains and metabolic processes. Of all the electron acceptors available to bacteria, utilization of O 2 yields the most energy while diversifying the type of substrates that a pathogen can use. Recent investigations have demonstrated important roles for bd -type quinol oxidases with high affinity for O 2 in bacterial pathogenesis. The investigations presented here have revealed that cytochrome bd potentiates virulence of a clinically relevant bacterial pathogen by fueling bioenergetics of prokaryotic cells while protecting the respiratory chain against NO toxicity. The adaptive antinitrosative defenses afforded by cytochrome bd synergize with other NO-detoxifying systems to preserve cellular bioenergetics, thereby promoting bacterial virulence in tissue hypoxia.

Природные материалы для сорбционной очистки хром- и кадмийсодержащих инфильтратов полигонов ТБО

2019 ◽  
pp. 13-19
Author(s):  
A. Safonov ◽  
N. Andriushchenko ◽  
N. Popova ◽  
K. Boldyrev
Keyword(s):  
Sorption Capacity ◽  
Electron Acceptors ◽  
Bacterial Cells ◽  
Maximum Sorption Capacity ◽  
Sorption Material ◽  
Maximum Sorption ◽  
Properties Of Materials ◽  
Solid Waste Landfills ◽  
Sorption Characteristics

Проведен анализ сорбционных характеристик природных материалов (вермикулит, керамзит, перлит, цеолит Трейд ) при очистке кадмий- и хромсодержащих сточных вод с высокой нагрузкой по ХПК. Установлено, что цеолит обладает максимальными сорбционными характеристиками для Cd и Cr и наименьшим биологическим обрастанием. При использовании вермикулита и керамзита или смесей на их основе можно ожидать увеличения сорбционной емкости для Cd и Сr при микробном обрастании, неизбежно происходящем в условиях контакта с водами, загрязненными органическими соединениями и биогенами. При этом биообрастание может повысить иммобилизационную способность материалов для редоксзависимых металлов за счет ферментативных ресурсов бактериальных клеток, использующих их в качестве акцепторов электронов. Эффект микробного обрастания разнонаправленно изменял параметры материалов: для Cr в большинстве случаев уменьшение и для Cd значительное увеличение. При этом дополнительным эффектом иммобилизации Cr является его биологическое восстановление биопленками. Варьируя состав сорбционного материала, можно подбирать смеси, оптимально подходящие для очистки вод инфильтратов с полигонов твердых бытовых отходов с высокой нагрузкой по ХПК и биогенным элементам как при использовании in situ, так и в системах на поверхности.The analysis of the sorption characteristics of natural materials (vermiculite, expanded clay, perlite, Trade zeolite) during the purification of cadmium and chromium-containing leachate with a high COD load was carried out. It was determined that zeolite had the maximum sorption capacity for Cd and Cr and the lowest biological fouling. When using vermiculite and expanded clay or mixtures on their basis, one can expect an increase in the sorption capacity for Cd and Cr during microbial fouling that inevitably occurs during contacting with water polluted with organic compounds and nutrients. In this case biofouling can increase the immobilization properties of materials for redox-dependent metals due to the enzymatic resources of bacterial cells that use them as electron acceptors. The effect of microbial fouling changed the parameters of materials in different directions: for Cr, in most cases, downward, and for Cd, significantly upward. Moreover, chromium biological recovery by biofilms is an additional effect of immobilization. Varying the composition of the sorption material provides for selecting mixtures that are optimally suitable for the purification of leachates from solid waste landfills with high COD and nutrients load, both when used in situ and in surface systems.

scholarly journals Radiation-Inactivated Acinetobacter baumannii Vaccine Candidates

Vaccines ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 96
Author(s):  
Stephen J. Dollery ◽  
Daniel V. Zurawski ◽  
Elena K. Gaidamakova ◽  
Vera Y. Matrosova ◽  
John K. Tobin ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Treatment Options ◽  
Bacterial Pathogen ◽  
Multidrug Resistant ◽  
Bacterial Cells ◽  
Wound Infections ◽  
Protein Profiles ◽  
Vaccine Candidates ◽  
Rich Media ◽  
Life Threatening

Acinetobacter baumannii is a bacterial pathogen that is often multidrug-resistant (MDR) and causes a range of life-threatening illnesses, including pneumonia, septicemia, and wound infections. Some antibiotic treatments can reduce mortality if dosed early enough before an infection progresses, but there are few other treatment options when it comes to MDR-infection. Although several prophylactic strategies have been assessed, no vaccine candidates have advanced to clinical trials or have been approved. Herein, we rapidly produced protective whole-cell immunogens from planktonic and biofilm-like cultures of A. baumannii, strain AB5075 grown using a variety of methods. After selecting a panel of five cultures based on distinct protein profiles, replicative activity was extinguished by exposure to 10 kGy gamma radiation in the presence of a Deinococcus antioxidant complex composed of manganous (Mn2+) ions, a decapeptide, and orthophosphate. Mn2+ antioxidants prevent hydroxylation and carbonylation of irradiated proteins, but do not protect nucleic acids, yielding replication-deficient immunogenic A. baumannii vaccine candidates. Mice were immunized and boosted twice with 1.0 × 107 irradiated bacterial cells and then challenged intranasally with AB5075 using two mouse models. Planktonic cultures grown for 16 h in rich media and biofilm cultures grown in static cultures underneath minimal (M9) media stimulated immunity that led to 80–100% protection.

scholarly journals Enhanced Arsenic Accumulation in Engineered Bacterial Cells Expressing ArsR

2004 ◽  
Vol 70 (8) ◽  
pp. 4582-4587 ◽  
Author(s):  
Jan Kostal ◽  
Rosanna Yang ◽  
Cindy H. Wu ◽  
Ashok Mulchandani ◽  
Wilfred Chen
Keyword(s):  
Cell Growth ◽  
Environmental Protection Agency ◽  
Arsenic Removal ◽  
Fusion Partner ◽  
Resting Cells ◽  
Bacterial Cells ◽  
High Affinity ◽  
Affinity Ligand ◽  
Arsenic Accumulation ◽  
Severe Reduction

ABSTRACT The metalloregulatory protein ArsR, which offers high affinity and selectivity toward arsenite, was overexpressed in Escherichia coli in an attempt to increase the bioaccumulation of arsenic. Overproduction of ArsR resulted in elevated levels of arsenite bioaccumulation but also a severe reduction in cell growth. Incorporation of an elastin-like polypeptide as the fusion partner to ArsR (ELP153AR) improved cell growth by twofold without compromising the ability to accumulate arsenite. Resting cells overexpressing ELP153AR accumulated 5- and 60-fold-higher levels of arsenate and arsenite than control cells without ArsR overexpression. Conversely, no significant improvement in Cd2+ or Zn2+ accumulation was observed, validating the specificity of ArsR. The high affinity of ArsR allowed 100% removal of 50 ppb of arsenite from contaminated water with these engineered cells, providing a technology useful to comply with the newly approved U.S. Environmental Protection Agency limit of 10 ppb. These results open up the possibility of using cells overexpressing ArsR as an inexpensive, high-affinity ligand for arsenic removal from contaminated drinking and ground water.

scholarly journals Cooperative Roles of Nitric Oxide-Metabolizing Enzymes To Counteract Nitrosative Stress in Enterohemorrhagic Escherichia coli

2019 ◽  
Vol 87 (9) ◽  
Author(s):  
Takeshi Shimizu ◽  
Akio Matsumoto ◽  
Masatoshi Noda
Keyword(s):  
Nitric Oxide ◽  
Escherichia Coli ◽  
Stationary Phase ◽  
Nitrosative Stress ◽  
Enterohemorrhagic Escherichia Coli ◽  
The Other ◽  
Anaerobic Growth ◽  
Bacterial Cells ◽  
Metabolizing Enzymes ◽  
Microaerobic Conditions

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) has at least three enzymes, NorV, Hmp, and Hcp, that act independently to lower the toxicity of nitric oxide (NO), a potent antimicrobial molecule. This study aimed to reveal the cooperative roles of these defensive enzymes in EHEC against nitrosative stress. Under anaerobic conditions, combined deletion of all three enzymes significantly increased the NO sensitivity of EHEC determined by the growth at late stationary phase; however, the expression of norV restored the NO resistance of EHEC. On the other hand, the growth of Δhmp mutant EHEC was inhibited after early stationary phase, indicating that NorV and Hmp play a cooperative role in anaerobic growth. Under microaerobic conditions, the growth of Δhmp mutant EHEC was inhibited by NO, indicating that Hmp is the enzyme that protects cells from NO stress under microaerobic conditions. When EHEC cells were exposed to a lower concentration of NO, the NO level in bacterial cells of Δhcp mutant EHEC was higher than those of the other EHEC mutants, suggesting that Hcp is effective at regulating NO levels only at a low concentration. These findings of a low level of NO in bacterial cells with hcp indicate that the NO consumption activity of Hcp was suppressed by Hmp at a low range of NO concentrations. Taken together, these results show that the cooperative effects of NO-metabolizing enzymes are regulated by the range of NO concentrations to which the EHEC cells are exposed.

Ultrasensitive fluorometric determination of iron(iii) and inositol hexaphosphate in cancerous and bacterial cells by using carbon dots with bright yellow fluorescence

The Analyst ◽  
2019 ◽  
Vol 144 (16) ◽  
pp. 5010-5021 ◽  
Author(s):  
Fangchao Cui ◽  
Jiadi Sun ◽  
Xingxing Yang ◽  
Jian Ji ◽  
Fuwei Pi ◽  
...  
Keyword(s):  
Living Cells ◽  
Dual Function ◽  
Bacterial Cells ◽  
Trace Detection ◽  
Ferric Ions ◽  
Fluorometric Determination ◽  
Inositol Hexaphosphate ◽  
Yellow Fluorescence ◽  
Bright Yellow

An ON–OFF–ON dual-function fluorescent nanoprobe is described for the trace detection of ferric ions and inositol hexaphosphate (IP6) in living cells.

scholarly journals Synthetic dual-function RNA reveals features necessary for target regulation

2021 ◽  
Author(s):  
Jordan J. Aoyama ◽  
Medha Raina ◽  
Gisela Storz
Keyword(s):  
Functional Organization ◽  
Regulatory Protein ◽  
Growth Conditions ◽  
Proper Function ◽  
Dual Function ◽  
Bacterial Cells ◽  
Base Pairing ◽  
Small Protein ◽  
Reading Frame ◽  
Small Proteins

Small base pairing RNAs (sRNAs) and small proteins comprise two classes of regulators that allow bacterial cells to adapt to a wide variety of growth conditions. A limited number of transcripts encoding both of these activities, regulation of mRNA expression by base pairing and synthesis of a small regulatory protein, have been identified. Given that few have been characterized, little is known about the interplay between the two regulatory functions. To investigate the competition between the two activities, we constructed synthetic dual-function RNAs, hereafter referred to as MgtSR or MgtRS, comprised of the Escherichia coli sRNA MgrR and the open reading frame encoding the small protein MgtS. MgrR is a 98 nt base pairing sRNA that negatively regulates eptB encoding phosphoethanolamine transferase. MgtS is a 31 aa small inner membrane protein that is required for the accumulation of MgtA, a magnesium (Mg 2+ ) importer. Expression of the separate genes encoding MgrR and MgtS is normally induced in response to low Mg 2+ by the PhoQP two-component system. By generating various versions of this synthetic dual-function RNA, we probed how the organization of components and the distance between the coding and base pairing sequences contribute to the proper function of both activities of a dual-function RNA. By understanding the features of natural and synthetic dual-function RNAs, future synthetic molecules can be designed to maximize their regulatory impact. IMPORTANCE Dual-function RNAs in bacteria encode a small protein and also base pair with mRNAs to act as small, regulatory RNAs. Given that only a limited number of dual-function RNAs have been characterized, further study of these regulators is needed to increase understanding of their features. This study demonstrates that a functional synthetic dual-regulator can be constructed from separate components and used to study the functional organization of dual-function RNAs, with the goal of exploiting these regulators.

scholarly journals The Use of an Organo-Selenium Peptide to Develop New Antimicrobials That Target a Specific Bacteria

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 611
Author(s):  
Phat Tran ◽  
Jonathan Kopel ◽  
Joe A. Fralick ◽  
Ted W. Reid
Keyword(s):  
Antibacterial Agent ◽  
Parent Strain ◽  
Bacterial Pathogen ◽  
Phage Display Library ◽  
Antigen Binding ◽  
E Coli ◽  
High Affinity ◽  
Novel Approach ◽  
F1 Antigen ◽  
Selection Of

This study examines the use of a covalently selenium-bonded peptide and phage that binds to the Yersinia pestis F1 antigen for the targeting and killing of E. coli expressing this surface antigen. Using a Ph.D.-12 phage-display library for affinity selection of the phage which would bind the F1 antigen of Y. pestis, a phage displaying a peptide that binds the F1 antigen with high affinity and specificity was identified. Selenium was then covalently attached to the display phage and the corresponding F1-antigen-binding peptide. Both the phage and peptides with selenium covalently attached retained their binding specificity for the Y. pestis F1 antigen. The phage or peptide not labeled with selenium did not kill the targeted bacteria, while the phage or peptide labeled with selenium did. In addition, the seleno-peptide, expressing the F1 targeting sequence only, killed cells expressing the F1 antigen but not the parent strain that did not express the F1 antigen. Specifically, the seleno-peptide could kill eight logs of bacteria in less than two hours at a 10-µM concentration. These results demonstrate a novel approach for the development of an antibacterial agent that can target a specific bacterial pathogen for destruction through the use of covalently attached selenium and will not affect other bacteria.

scholarly journals Oxidative respiration through the bd-I and cbb3 oxidases is required for Vibrio cholerae pathogenicity and proliferation in vivo.

2021 ◽  
Author(s):  
Andrew John Van Alst ◽  
Lucas Maurice Demey ◽  
Victor DiRita
Keyword(s):  
Vibrio Cholerae ◽  
Anaerobic Respiration ◽  
Bacterial Pathogen ◽  
Population Expansion ◽  
Amplicon Sequencing ◽  
Electron Acceptors ◽  
Infant Mouse ◽  
Small Intestinal ◽  
Oxidative Respiration

Vibrio cholerae respires both aerobically and anaerobically and, while oxygen may be available to it during infection, other terminal electron acceptors are proposed for population expansion during infection. Unlike gastrointestinal pathogens that stimulate significant inflammation leading to elevated levels of oxygen or alternative terminal electron acceptors, V. cholerae infections are not understood to induce a notable inflammatory response. To ascertain the respiration requirements of V. cholerae during infection, we used Multiplex Genome Editing by Natural Transformation (MuGENT) to create V. cholerae strains lacking aerobic or anaerobic respiration. V. cholerae strains lacking aerobic respiration were attenuated in infant mice 10 5 -fold relative to wild type, while strains lacking anaerobic respiration had no colonization defect, contrary to earlier work suggesting a role for anaerobic respiration during infection. Using several approaches, including one we developed for this work termed Comparative Multiplex PCR Amplicon Sequencing (CoMPAS), we determined that the bd-I and cbb3 oxidases are essential for small intestinal colonization of V. cholerae in the infant mouse. The bd-I oxidase was also determined as the primary oxidase during growth outside the host, making V. cholerae the only example of a Gram-negative bacterial pathogen in which a bd-type oxidase is the primary oxidase for energy acquisition inside and outside of a host.

scholarly journals Karyopherin Kap114p regulates TATA-binding protein-mediated transcription

2018 ◽  
Author(s):  
Chung-Chi Liao ◽  
Sahana Shankar ◽  
Golam Rizvee Ahmed ◽  
Kuo-Chiang Hsia
Keyword(s):  
Nuclear Import ◽  
Basic Protein ◽  
Binding Protein ◽  
Tata Binding Protein ◽  
Dual Function ◽  
Temperature Sensitive ◽  
High Affinity ◽  
Binding Domains ◽  
Transport Receptors ◽  
Competitive Inhibitors

SUMMARYGene expression is regulated by nuclear accessibility of transcription factors controlled by transport receptors and competitive inhibitors. Multiple karyopherin-βs (Kap-βs) facilitate nuclear import of yeast TATA-binding protein (yTBP). However, only Kap114p suppresses temperature-sensitive yTBP mutations, suggesting Kap114p executes undefined non-transport functions. We show that yTBP preferably binds Kap114p with an affinity three orders of magnitude higher than other Kap-βs facilitating yTBP nuclear import. Our crystal structure of Kap114p reveals an extensively negatively-charged concave surface, accounting for high-affinity basic-protein binding. Furthermore, we biochemically demonstrate that two intra-HEAT-repeat inserts act as regulatory TBP-binding domains carried by TBP-associated factor 1 (TAF1-TAND), suppressing binding of yTBP with DNA and the transcription factor IIA. Remarkably, dual-knockout of Kap114 and TAF1-TAND in yeast synergistically suppresses cell growth. Our study reveals that Kap114p has a dual function that modulates the nuclear localization and activity of yTBP, illuminating how the nuclear transport machinery regulates yTBP-mediated transcription.

Sign in / Sign up

Export Citation Format

Share Document