scholarly journals Selective Nutrient Transport in Bacteria: Multicomponent Transporter Systems Reign Supreme

2021 ◽  
Vol 8 ◽  
Author(s):  
James S. Davies ◽  
Michael J. Currie ◽  
Joshua D. Wright ◽  
Michael C. Newton-Vesty ◽  
Rachel A. North ◽  
...  
Keyword(s):  
Nutrient Transport ◽  
Transport Systems ◽  
Multicomponent Transport ◽  
High Affinity ◽  
Wide Range ◽  
Membrane Bound ◽  
Transporter Systems ◽  
Substrate Binding Protein ◽  
Review Current

Multicomponent transporters are used by bacteria to transport a wide range of nutrients. These systems use a substrate-binding protein to bind the nutrient with high affinity and then deliver it to a membrane-bound transporter for uptake. Nutrient uptake pathways are linked to the colonisation potential and pathogenicity of bacteria in humans and may be candidates for antimicrobial targeting. Here we review current research into bacterial multicomponent transport systems, with an emphasis on the interaction at the membrane, as well as new perspectives on the role of lipids and higher oligomers in these complex systems.

scholarly journals The Role of Exosomes in the Crosstalk between Adipocytes and Liver Cancer Cells

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 1988
Author(s):  
Leslimar Rios-Colon ◽  
Elena Arthur ◽  
Suryakant Niture ◽  
Qi Qi ◽  
John T. Moore ◽  
...  
Keyword(s):  
Liver Cancer ◽  
Cancer Cells ◽  
Bioactive Materials ◽  
Liver Cancer Cells ◽  
Secreted Factors ◽  
Wide Range ◽  
Pathophysiological Role ◽  
Inflammatory State ◽  
Membrane Bound

Exosomes are membrane-bound extracellular vesicles (EVs) that transport bioactive materials between cells and organs. The cargo delivered by exosomes can alter a wide range of cellular responses in recipient cells and play an important pathophysiological role in human cancers. In hepatocellular carcinoma (HCC), for example, adipocyte- and tumor-secreted factors contained in exosomes contribute to the creation of a chronic inflammatory state, which contributes to disease progression. The exosome-mediated crosstalk between adipocytes and liver cancer cells is a key aspect of a dynamic tumor microenvironment. In this review, we summarize the role of increased adiposity and the role of adipocyte-derived exosomes (AdExos) and HCC-derived exosomes (HCCExos) in the modulation of HCC progression. We also discuss recent advances regarding how malignant cells interact with the surrounding adipose tissue and employ exosomes to promote a more aggressive phenotype.

scholarly journals Vibrio Iron Transport: Evolutionary Adaptation to Life in Multiple Environments

2015 ◽  
Vol 80 (1) ◽  
pp. 69-90 ◽  
Author(s):  
Shelley M. Payne ◽  
Alexandra R. Mey ◽  
Elizabeth E. Wyckoff
Keyword(s):  
Regulatory Networks ◽  
Iron Transport ◽  
Horizontal Transmission ◽  
Essential Element ◽  
Transport Systems ◽  
Iron Binding ◽  
Content Type ◽  
High Affinity ◽  
Wide Range ◽  
Genes Encoding

SUMMARYIron is an essential element forVibriospp., but the acquisition of iron is complicated by its tendency to form insoluble ferric complexes in nature and its association with high-affinity iron-binding proteins in the host. Vibrios occupy a variety of different niches, and each of these niches presents particular challenges for acquiring sufficient iron.Vibriospecies have evolved a wide array of iron transport systems that allow the bacteria to compete for this essential element in each of its habitats. These systems include the secretion and uptake of high-affinity iron-binding compounds (siderophores) as well as transport systems for iron bound to host complexes. Transporters for ferric and ferrous iron not complexed to siderophores are also common toVibriospecies. Some of the genes encoding these systems show evidence of horizontal transmission, and the ability to acquire and incorporate additional iron transport systems may have allowedVibriospecies to more rapidly adapt to new environmental niches. While too little iron prevents growth of the bacteria, too much can be lethal. The appropriate balance is maintained in vibrios through complex regulatory networks involving transcriptional repressors and activators and small RNAs (sRNAs) that act posttranscriptionally. Examination of the number and variety of iron transport systems found inVibriospp. offers insights into how this group of bacteria has adapted to such a wide range of habitats.

Oxygen-sensitive membrane transporters in vertebrate red cells

2000 ◽  
Vol 203 (9) ◽  
pp. 1395-1407 ◽  
Author(s):  
J.S. Gibson ◽  
A.R. Cossins ◽  
J.C. Ellory
Keyword(s):  
Membrane Transporters ◽  
Red Cells ◽  
Transport Systems ◽  
Red Cell ◽  
Organic Systems ◽  
Wide Range ◽  
Oxygen Sensitive ◽  
Radical Generation ◽  
Membrane Transport Systems

Oxygen is essential for all higher forms of animal life. It is required for oxidative phosphorylation, which forms the bulk of the energy supply of most animals. In many vertebrates, transport of O(2) from respiratory to other tissues, and of CO(2) in the opposite direction, involves red cells. These are highly specialised, adapted for their respiratory function. Intracellular haemoglobin, carbonic anhydrase and the membrane anion exchanger (AE1) increase the effective O(2)- and CO(2)-carrying capacity of red cells by approximately 100-fold. O(2) also has a pathological role. It is a very reactive species chemically, and oxidation, free radical generation and peroxide formation can be major hazards. Cells that come into contact with potentially damaging levels of O(2) have a variety of systems to protect them against oxidative damage. Those in red cells include catalase, superoxide dismutase and glutathione. In this review, we focus on a third role of O(2), as a regulator of membrane transport systems, a role with important consequences for the homeostasis of the red cell and also the organism as a whole. We show that regulation of red cell transporters by O(2) is widespread throughout the vertebrate kingdom. The effect of O(2) is selective but involves a wide range of transporters, including inorganic and organic systems, and both electroneutral and conductive pathways. Finally, we discuss what is known about the mechanism of the O(2) effect and comment on its physiological and pathological roles.

scholarly journals Analysis of Sustainable Transport for Smart Cities

2019 ◽  
Vol 11 (7) ◽  
pp. 2140 ◽  
Author(s):  
Dastan Bamwesigye ◽  
Petra Hlavackova
Keyword(s):  
Urban Areas ◽  
Smart Cities ◽  
Well Being ◽  
Transportation Systems ◽  
Transport Systems ◽  
Sustainable Transport ◽  
Urban Centers ◽  
Modern Cities ◽  
Wide Range

For decades, transportation has been considered as a link to all aspects of life worldwide. In this case, the world’s natural environment, social well-being and economic development all usually depend on transportation systems. In most cases, safe, clean, sustainable and equitable transport systems help countries, especially in cities and urban centers, to thrive. However, a wide range of research shows that transportation systems in most of the cities and urban areas are unsustainable. In fact, some of these transportation systems are considered to be a threat to the environmental, social and economical aspects of future generations. In this perspective, therefore, changing such trends in transportation requires the collaboration of various stakeholders at regional, national and international levels. In this paper, therefore, a wide range of definitions of sustainable transport are discussed. More so, some of the aspects of smart transport for modern cities such as cycling and the role of women in sustainable transport were explored. With the aim of getting to the core of the subject, cases of women in bicycle transport, especially in the Netherlands and Germany compared to Kenya and Uganda are equally elucidated. Although not fully outlined, the idea of smart cities and sustainable transport have heterogeneous characteristics globally as discussed herein.

scholarly journals Zinc Competition among the Intestinal Microbiota

mBio ◽  
2012 ◽  
Vol 3 (4) ◽  
Author(s):  
Lindsay M. Gielda ◽  
Victor J. DiRita
Keyword(s):  
Gastrointestinal Tract ◽  
Campylobacter Jejuni ◽  
Pathogenic Bacteria ◽  
Zinc Transporter ◽  
Zinc Uptake ◽  
Zinc Binding ◽  
Transport Systems ◽  
Content Type ◽  
High Affinity ◽  
Wide Range

ABSTRACT Bioavailable levels of trace metals, such as iron and zinc, for bacterial growth in nature are sufficiently low that most microbes have evolved high-affinity binding and transport systems. The microbe Campylobacter jejuni lives in the gastrointestinal tract of chickens, the principal source of human infection. A high-affinity ABC transporter for zinc uptake is required for Campylobacter survival in chicken intestines in the presence of a normal microbiota but not when chickens are raised with a limited microbiota. Mass spectrometric analysis of cecal contents revealed the presence of numerous zinc-binding proteins in conventional chicks compared to the number in limited-microbiota chicks. The presence of a microbiota results in the production of host zinc-binding enzymes, causing a growth restriction for bacteria that lack the high-affinity zinc transporter. Such transporters in a wide range of pathogenic bacteria make them good targets for the development of broad-spectrum antimicrobials. IMPORTANCE Zinc is an essential trace element for the growth of most organisms. Quantities of zinc inside cells are highly regulated, as too little zinc does not support growth, while too much zinc is toxic. Numerous bacterial cells require zinc uptake systems for growth and virulence. The work presented here demonstrates that the microbiota in the gastrointestinal tract reduces the quantity of zinc. Without a high-affinity zinc transporter, Campylobacter jejuni, a commensal organism of chickens, is unable to replicate or colonize the gastrointestinal tract. This is the first demonstration of zinc competition between microbiota in the gastrointestinal tract of a host. These results could have profound implications in the field of microbial pathogenesis and in our understanding of host metabolism and the microbiota.

scholarly journals Characterization of the Role of a Non-GPCR Membrane-Bound CFEM Protein in the Pathogenicity and Germination of Botrytis cinerea

2020 ◽  
Vol 8 (7) ◽  
pp. 1043
Author(s):  
Gulab Chand Arya ◽  
Dhruv Aditya Srivastava ◽  
Eswari P. J. Pandaranayaka ◽  
Ekaterina Manasherova ◽  
Dov Bernard Prusky ◽  
...  
Keyword(s):  
Botrytis Cinerea ◽  
Pathogenic Fungi ◽  
Phytopathogenic Fungi ◽  
Fungal Virulence ◽  
Wide Range ◽  
Membrane Bound ◽  
The Common ◽  
G Protein Coupled

The necrotrophic fungus Botrytis cinerea, is considered a major cause of postharvest losses in a wide range of crops. The common fungal extracellular membrane protein (CFEM), containing a conserved eight-cysteine pattern, was found exclusively in fungi. Previous studies in phytopathogenic fungi have demonstrated the role of membrane-bound and secreted CFEM-containing proteins in different aspects of fungal virulence. However, non-G protein-coupled receptor (non-GPCR) membrane CFEM proteins have not been studied yet in phytopathogenic fungi. In the present study, we have identified a non-GPCR membrane-bound CFEM-containing protein, Bcin07g03260, in the B. cinerea genome, and generated deletion mutants, ΔCFEM-Bcin07g03260, to study its potential role in physiology and virulence. Three independent ΔCFEM-Bcin07g03260 mutants showed significantly reduced progression of a necrotic lesion on tomato (Solanum lycopersicum) leaves. Further analysis of the mutants revealed significant reduction (approximately 20–30%) in conidial germination and consequent germ tube elongation compared with the WT. Our data complements a previous study of secreted ΔCFEM1 mutants of B. cinerea that showed reduced progression of necrotic lesions on leaves, without effect on germination. Considering various functions identified for CFEM proteins in fungal virulence, our work illustrates a potential new role for a non-GPCR membrane CFEM in pathogenic fungi to control virulence in the fungus B. cinerea.

scholarly journals Nonspecific nuclear uptake of anti-MUC1 aptamers by dead cells: the role of cell viability monitoring in aptamer targeting of membrane-bound protein cancer biomarkers

2021 ◽  
Vol 13 (9) ◽  
pp. 1191-1203
Author(s):  
Shane Patrick Flanagan ◽  
Ronen Fogel ◽  
Adrienne Lesley Edkins ◽  
Lance St. John Ho ◽  
Janice Limson
Keyword(s):  
Cell Viability ◽  
Cancer Biomarkers ◽  
Nuclear Uptake ◽  
High Affinity ◽  
Membrane Bound

The nonspecific uptake of aptamers by dead cells is an often-overlooked factor during the study of aptamer binding to their targetsin vivo. Accounting for this can aid in the identification of aptamers with high affinity and specificity.

scholarly journals Structure of an ABC transporter solute-binding protein specific for the amino sugars glucosamine and galactosamine

2016 ◽  
Vol 72 (6) ◽  
pp. 467-472 ◽  
Author(s):  
Umesh Yadava ◽  
Matthew W. Vetting ◽  
Nawar Al Obaidi ◽  
Michael S. Carter ◽  
John A. Gerlt ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Binding Protein ◽  
Transport Systems ◽  
Amino Sugars ◽  
Ligand Binding Site ◽  
Agrobacterium Vitis ◽  
High Affinity ◽  
Differential Scanning Fluorimetry ◽  
Membrane Bound ◽  
Ribose Binding Protein

The uptake of exogenous solutes by prokaryotes is mediated by transport systems embedded in the plasma membrane. In many cases, a solute-binding protein (SBP) is utilized to bind ligands with high affinity and deliver them to the membrane-bound components responsible for translocation into the cytoplasm. In the present study, Avi_5305, anAgrobacterium vitisSBP belonging to Pfam13407, was screened by differential scanning fluorimetry (DSF) and found to be stabilized by D-glucosamine and D-galactosamine. Avi_5305 is the first protein from Pfam13407 shown to be specific for amino sugars, and co-crystallization resulted in structures of Avi_5305 bound to D-glucosamine and D-galactosamine. Typical of Pfam13407, Avi_5305 consists of two α/β domains linked through a hinge region, with the ligand-binding site located in a cleft between the two domains. Comparisons withEscherichia coliribose-binding protein suggest that a cation–π interaction with Tyr168 provides the specificity for D-glucosamine/D-galactosamine over D-glucose/D-galactose.

Specific Estradiol Binding in Schwannomas, Meningiomas, and Neurofibromas

Neurosurgery ◽  
1981 ◽  
Vol 9 (6) ◽  
pp. 665-671 ◽  
Author(s):  
Robert L. Martuza ◽  
David T. MacLaughlin ◽  
Robert G. Ojemann
Keyword(s):  
Binding Sites ◽  
Genetic Disorder ◽  
High Affinity ◽  
Acoustic Neuromas ◽  
Saturation Binding ◽  
Plot Analysis ◽  
Wide Range ◽  
Scatchard Plot Analysis ◽  
Range Of Values

Abstract The cytoplasmic fractions of schwannomas (acoustic neuromas), meningiomas, and neurofibromas were assayed for the presence of estrogen receptors. Specific estradiol binding was detected in 7 of 16 schwannomas, 7 of 10 meningiomas, and 1 of 6 neurofibromas. A nontumorous vestibular nerve was also studied and showed no estradiol binding. In the tumors, the concentration of the estradiol binding sites as estimated by saturation binding analysis covered a wide range of values (21 to 2430 fmol/g of tumor) but, overall, meningiomas contained the highest amount of estradiol binder. A Scatchard plot analysis of one of the schwannoma specimens demonstrated high affinity estradiol binding (Ka = 1.695 × 1010M−1). Although there were more females than males in each tumor category, the overall incidence of estradiol binding was similar in males (5 of 11. 45%) and in females (10 of 21, 48%r). In 5 cases, progestin binding was also measured and was delected in two meningiomas (both from female patients): one meningioma and two neurofibromas showed no progestin binding. A discussion is presented of the possible role of estradiol in the pathogenesis or modulation of meningeal and Schwann cell tumors as well as in the genetic disorder neurofibromatosis.

Validation of a sensitive direct assay for melatonin for investigation of circadian rhythms in different species

1985 ◽  
Vol 106 (3) ◽  
pp. 387-394 ◽  
Author(s):  
G. E. Webley ◽  
H. Mehl ◽  
K. P. Willey
Keyword(s):  
Specific Activity ◽  
Biological Fluids ◽  
High Specific Activity ◽  
Male Rat ◽  
Rat Serum ◽  
Menstrual Cycles ◽  
High Affinity ◽  
Direct Assay ◽  
Wide Range

ABSTRACT The role of melatonin in animals which do not show marked seasonal changes in reproduction is disputed, in part because of the wide variation in reported concentrations. One reason for this may be the difficulties associated with the measurement of low molar concentrations of melatonin and the presence of a wide variety of potentially cross-reacting substances. The availability of a high affinity antiserum has allowed an assay, with low cross-reactivity and good sensitivity, to be established for the direct measurement of melatonin in a wide range of biological fluids, in particular serum, plasma and follicular fluid from man and rat. The high affinity of the antiserum enabled a tritium label of high specific activity to be used, removing the problems associated with the iodination of a small molecular weight compound. Melatonin concentrations in the assay were evaluated by four different methods: UV absorbance, gas chromatography, comparison of the immunoreactive concentrations of the label with the expected concentration by dilution and by comparison with a previously established assay which uses the same antiserum. Melatonin was measured in serum from twelve healthy women over two 24-h periods; eight women with normal menstrual cycles and four taking the contraceptive pill. Concentrations were found to range from 19·8 to 215 pmol/l during the day in both groups. In women with normal menstrual cycles peak concentrations of 513·2 ± 54·1 (s.e.m.) pmol/l were recorded at 04.00 h, whereas higher concentrations were found in women taking the pill, reaching a peak of 849·12 ± 21·8 (s.e.m.) pmol/l at 04.00 h. Similar melatonin concentrations were measured in the two 24-h periods. In the adult male rat, serum melatonin concentrations varied from 92·66 ± 37·9 (s.e.m.) pmol/l at 12.00 h, rising to 526 ± 55·6 (s.e.m.) pmol/l at 04.00 h. This direct assay is more practical and robust than the assays currently available. The careful validation of assay characteristics allows its widespread use in both clinical studies and the investigation of the role of melatonin in different species. J. Endocr. (1985) 106, 387–394

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