scholarly journals Holins in Bacteria, Eukaryotes, and Archaea: Multifunctional Xenologues with Potential Biotechnological and Biomedical Applications

2014 ◽  
Vol 197 (1) ◽  
pp. 7-17 ◽  
Author(s):  
Milton H. Saier ◽  
Bhaskara L. Reddy
Keyword(s):  
Cell Death ◽  
Biomedical Applications ◽  
Cell Lysis ◽  
Gram Negative Bacteria ◽  
Bacterial Genomes ◽  
Future Studies ◽  
Virion Release ◽  
Cytoplasmic Membranes ◽  
Domains Of Life ◽  
The Many

Holins form pores in the cytoplasmic membranes of bacteria for the primary purpose of releasing endolysins that hydrolyze the cell wall and induce cell death. Holins are encoded within bacteriophage genomes, where they promote cell lysis for virion release, and within bacterial genomes, where they serve a diversity of potential or established functions. These include (i) release of gene transfer agents, (ii) facilitation of programs of differentiation such as those that allow sporulation and spore germination, (iii) contribution to biofilm formation, (iv) promotion of responses to stress conditions, and (v) release of toxins and other proteins. There are currently 58 recognized families of holins and putative holins with members exhibiting between 1 and 4 transmembrane α-helical spanners, but many more families have yet to be discovered. Programmed cell death in animals involves holin-like proteins such as Bax and Bak that may have evolved from bacterial holins. Holin homologues have also been identified in archaea, suggesting that these proteins are ubiquitous throughout the three domains of life. Phage-mediated cell lysis of dual-membrane Gram-negative bacteria also depends on outer membrane-disrupting “spanins” that function independently of, but in conjunction with, holins and endolysins. In this minireview, we provide an overview of their modes of action and the first comprehensive summary of the many currently recognized and postulated functions and uses of these cell lysis systems. It is anticipated that future studies will result in the elucidation of many more such functions and the development of additional applications.

scholarly journals Biomedical Uses of Sulfobetaine-Based Zwitterionic Materials

2020 ◽  
Vol 02 (04) ◽  
pp. 342-357
Author(s):  
Francesco Zaccarian ◽  
Matthew B. Baker ◽  
Matthew J. Webber
Keyword(s):  
Biomedical Applications ◽  
Foreign Body Reaction ◽  
Inflammatory Responses ◽  
Cellular Adhesion ◽  
Review Of The Literature ◽  
Future Prospects ◽  
Protein Fouling ◽  
Biomedical Device ◽  
The Many ◽  
Hydrophilic Coatings

Protein fouling can render a biomedical device dysfunctional, and also serves to nucleate the foreign body reaction to an implanted material. Hydrophilic coatings have emerged as a commonly applied route to combat interface-mediated complications and promote device longevity and limited inflammatory response. While polyethylene glycol has received a majority of the attention in this regard, coatings based on zwitterionic moieties have been more recently explored. Sulfobetaines in particular constitute one such class of zwitterions explored for use in mitigating surface fouling, and have been shown to reduce protein adsorption, limit cellular adhesion, and promote increased functional lifetimes and limited inflammatory responses when applied to implanted materials and devices. Here, we present a focused review of the literature surrounding sulfobetaine, beginning with an understanding of its chemistry and the methods by which it is applied to the surface of a biomedical device in molecular and polymeric forms, and then advancing to the many early demonstrations of function in a variety of biomedical applications. Finally, we provide some insights into the benefits and challenges presented by its use, as well as some outlook on the future prospects for using this material to improve biomedical device practice by addressing interface-mediated complications.

scholarly journals Ozone responses in Arabidopsis: beyond stomatal conductance

2021 ◽  
Author(s):  
Luis O Morales ◽  
Alexey Shapiguzov ◽  
Omid Safronov ◽  
Johanna Leppälä ◽  
Lauri Vaahtera ◽  
...  
Keyword(s):  
Cell Death ◽  
Tropospheric Ozone ◽  
Natural Variation ◽  
Air Pollutant ◽  
Plant Responses ◽  
Negative Effects ◽  
Transcriptional Responses ◽  
Physiological Mechanisms ◽  
Future Studies ◽  
Key Parameter

Abstract Tropospheric ozone (O3) is a major air pollutant that decreases yield of important crops worldwide. Despite long-lasting research of its negative effects on plants, there are many gaps in our knowledge on how plants respond to O3. In this study, we used natural variation in the model plant Arabidopsis (Arabidopsis thaliana) to characterize molecular and physiological mechanisms underlying O3 sensitivity. A key parameter in models for O3 damage is stomatal uptake. Here we show that the extent of O3 damage in the sensitive Arabidopsis accession Shahdara (Sha) does not correspond with O3 uptake, pointing toward stomata-independent mechanisms for the development of O3 damage. We compared tolerant (Col-0) versus sensitive accessions (Sha, Cvi-0) in assays related to photosynthesis, cell death, antioxidants, and transcriptional regulation. Acute O3 exposure increased cell death, development of lesions in the leaves, and decreased photosynthesis in sensitive accessions. In both Sha and Cvi-0, O3-induced lesions were associated with decreased maximal chlorophyll fluorescence and low quantum yield of electron transfer from Photosystem II to plastoquinone. However, O3-induced repression of photosynthesis in these two O3-sensitive accessions developed in different ways. We demonstrate that O3 sensitivity in Arabidopsis is influenced by genetic diversity given that Sha and Cvi-0 developed accession-specific transcriptional responses to O3. Our findings advance the understanding of plant responses to O3 and set a framework for future studies to characterize molecular and physiological mechanisms allowing plants to respond to high O3 levels in the atmosphere as a result of high air pollution and climate change.

scholarly journals Captivating Perplexities of Spinareovirinae 5′ RNA Caps

Viruses ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 294
Author(s):  
Justine Kniert ◽  
Qi Feng Lin ◽  
Maya Shmulevitz
Keyword(s):  
Immune Recognition ◽  
Domains Of Life ◽  
The Many ◽  
Rna Capping ◽  
Multiple Domains ◽  
Rna Caps

RNAs with methylated cap structures are present throughout multiple domains of life. Given that cap structures play a myriad of important roles beyond translation, such as stability and immune recognition, it is not surprising that viruses have adopted RNA capping processes for their own benefit throughout co-evolution with their hosts. In fact, that RNAs are capped was first discovered in a member of the Spinareovirinae family, Cypovirus, before these findings were translated to other domains of life. This review revisits long-past knowledge and recent studies on RNA capping among members of Spinareovirinae to help elucidate the perplex processes of RNA capping and functions of RNA cap structures during Spinareovirinae infection. The review brings to light the many uncertainties that remain about the precise capping status, enzymes that facilitate specific steps of capping, and the functions of RNA caps during Spinareovirinae replication.

scholarly journals Biomarkers of Radiotherapy-Induced Immunogenic Cell Death

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 930
Author(s):  
Rianne D. W. Vaes ◽  
Lizza E. L. Hendriks ◽  
Marc Vooijs ◽  
Dirk De Ruysscher
Keyword(s):  
Cell Death ◽  
Immune Responses ◽  
Tumor Cells ◽  
Immunogenic Cell Death ◽  
Type I ◽  
Future Studies ◽  
Regulated Cell Death ◽  
Molecular Patterns ◽  
Damage Associated Molecular Patterns ◽  
Potential Biomarkers

Radiation therapy (RT) can induce an immunogenic variant of regulated cell death that can initiate clinically relevant tumor-targeting immune responses. Immunogenic cell death (ICD) is accompanied by the exposure and release of damage-associated molecular patterns (DAMPs), chemokine release, and stimulation of type I interferon (IFN-I) responses. In recent years, intensive research has unraveled major mechanistic aspects of RT-induced ICD and has resulted in the identification of immunogenic factors that are released by irradiated tumor cells. However, so far, only a limited number of studies have searched for potential biomarkers that can be used to predict if irradiated tumor cells undergo ICD that can elicit an effective immunogenic anti-tumor response. In this article, we summarize the available literature on potential biomarkers of RT-induced ICD that have been evaluated in cancer patients. Additionally, we discuss the clinical relevance of these findings and important aspects that should be considered in future studies.

scholarly journals Lysis Genes of the Bacillus subtilisDefective Prophage PBSX

1998 ◽  
Vol 180 (8) ◽  
pp. 2110-2117 ◽  
Author(s):  
Susanne Krogh ◽  
Steen T. Jørgensen ◽  
Kevin M. Devine
Keyword(s):  
Functional Analysis ◽  
Host Cell ◽  
Expression System ◽  
Cell Lysis ◽  
Lethal Gene ◽  
Gram Negative Bacteria ◽  
Gene Products ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Exported Protein

ABSTRACT Four genes identified within the late operon of PBSX show characteristics expected of a host cell lysis system; they arexepA, encoding an exported protein; xhlA, encoding a putative membrane-associated protein; xhlB, encoding a putative holin; and xlyA, encoding a putative endolysin. In this work, we have assessed the contribution of each gene to host cell lysis by expressing the four genes in different combinations under the control of their natural promoter located on the chromosome of Bacillus subtilis 168. The results show thatxepA is unlikely to be involved in host cell lysis. Expression of both xhlA and xhlB is necessary to effect host cell lysis of B. subtilis. Expression ofxhlB (encoding the putative holin) together withxlyA (encoding the endolysin) cannot effect cell lysis, indicating that the PBSX lysis system differs from those identified in the phages of gram-negative bacteria. Since host cell lysis can be achieved when xlyA is inactivated, it is probable that PBSX encodes a second endolysin activity which also uses XhlA and XhlB for export from the cell. The chromosome-based expression system developed in this study to investigate the functions of the PBSX lysis genes should be a valuable tool for the analysis of other host cell lysis systems and for expression and functional analysis of other lethal gene products in gram-positive bacteria.

Staphylococcal ClpXP protease targets the cellular antioxidant system to eliminate fitness-compromised cells in stationary phase

2021 ◽  
Vol 118 (47) ◽  
pp. e2109671118
Author(s):  
Abdulelah A. Alqarzaee ◽  
Sujata S. Chaudhari ◽  
Mohammad Mazharul Islam ◽  
Vikas Kumar ◽  
Matthew C. Zimmerman ◽  
...  
Keyword(s):  
Cell Death ◽  
Stationary Phase ◽  
Growth Conditions ◽  
Significant Loss ◽  
Protein Damage ◽  
Bacterial Populations ◽  
Competitive Fitness ◽  
Functional Conservation ◽  
Domains Of Life ◽  
Expression And Activity

The transition from growth to stationary phase is a natural response of bacteria to starvation and stress. When stress is alleviated and more favorable growth conditions return, bacteria resume proliferation without a significant loss in fitness. Although specific adaptations that enhance the persistence and survival of bacteria in stationary phase have been identified, mechanisms that help maintain the competitive fitness potential of nondividing bacterial populations have remained obscure. Here, we demonstrate that staphylococci that enter stationary phase following growth in media supplemented with excess glucose, undergo regulated cell death to maintain the competitive fitness potential of the population. Upon a decrease in extracellular pH, the acetate generated as a byproduct of glucose metabolism induces cytoplasmic acidification and extensive protein damage in nondividing cells. Although cell death ensues, it does not occur as a passive consequence of protein damage. Instead, we demonstrate that the expression and activity of the ClpXP protease is induced, resulting in the degeneration of cellular antioxidant capacity and, ultimately, cell death. Under these conditions, inactivation of either clpX or clpP resulted in the extended survival of unfit cells in stationary phase, but at the cost of maintaining population fitness. Finally, we show that cell death from antibiotics that interfere with bacterial protein synthesis can also be partly ascribed to the corresponding increase in clpP expression and activity. The functional conservation of ClpP in eukaryotes and bacteria suggests that ClpP-dependent cell death and fitness maintenance may be a widespread phenomenon in these domains of life.

scholarly journals Roundup®, but Not Roundup-Ready® Corn, Increases Mortality of Drosophila melanogaster

Toxics ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 38
Author(s):  
Becky Talyn ◽  
Rachael Lemon ◽  
Maryam Badoella ◽  
Darwin Melchiorre ◽  
Maryori Villalobos ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Genetically Modified ◽  
Genetically Modified Foods ◽  
Herbicide Application ◽  
Reproductive Behaviors ◽  
Future Studies ◽  
Toxicological Effects ◽  
The Us ◽  
Biochemical Mechanisms ◽  
The Many

Genetically modified foods have become pervasive in diets of people living in the US. By far the most common genetically modified foods either tolerate herbicide application (HT) or produce endogenous insecticide (Bt). To determine whether these toxicological effects result from genetic modification per se, or from the increase in herbicide or insecticide residues present on the food, we exposed fruit flies, Drosophila melanogaster, to food containing HT corn that had been sprayed with the glyphosate-based herbicide Roundup®, HT corn that had not been sprayed with Roundup®, or Roundup® in a variety of known glyphosate concentrations and formulations. While neither lifespan nor reproductive behaviors were affected by HT corn, addition of Roundup® increased mortality with an LC50 of 7.1 g/L for males and 11.4 g/L for females after 2 days of exposure. Given the many genetic tools available, Drosophila are an excellent model system for future studies about genetic and biochemical mechanisms of glyphosate toxicity.

scholarly journals In Vitro Anti-Helicobacter pyloriActivities of New Rifamycin Derivatives, KRM-1648 and KRM-1657

1999 ◽  
Vol 43 (5) ◽  
pp. 1072-1076 ◽  
Author(s):  
Junko K. Akada ◽  
Mutsunori Shirai ◽  
Kenji Fujii ◽  
Kiwamu Okita ◽  
Teruko Nakazawa
Keyword(s):  
Helicobacter Pylori ◽  
Cell Lysis ◽  
Antimicrobial Activities ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Bactericidal Activities ◽  
H Pylori ◽  
Time Kill

ABSTRACT The new rifamycin derivatives KRM-1657 and KRM-1648 were evaluated for their in vitro antimicrobial activities against 44 strains ofHelicobacter pylori. Although the drugs were not very active against other gram-negative bacteria, the MICs at which 90% of isolates are inhibited for these drugs were lower (0.002 and 0.008 μg/ml, respectively) than those of amoxicillin and rifampin forH. pylori. Time-kill studies revealed that the bactericidal activities of these agents were due to cell lysis. The results presented here indicate that these new rifamycin derivatives may be useful for the eradication of H. pylori infections.

PPK1 and PPK2 — which polyphosphate kinase is older?

Biologia ◽  
2014 ◽  
Vol 69 (3) ◽  
Author(s):  
Lucia Achbergerová ◽  
Jozef Nahálka
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Phylogenetic Analyses ◽  
Linear Molecule ◽  
Polyphosphate Kinase ◽  
Hypothetical Proteins ◽  
Bacterial Genomes ◽  
Metabolic Balance ◽  
Domains Of Life

AbstractPolyphosphate kinases (PPKs) catalyse the polymerisation and degradation of polyphosphate chains. As a result of this process, PPK produces or consumes energy in the form of ATP. Polyphosphate is a linear molecule that contains tens to hundreds of phosphate residues connected by macroergic bonds, and it appears to be an easily obtainable and rich source of energy from prebiotic times to the present. Notably, polyphosphate is present in the cells of all three domains of life, but PPKs are widely distributed only in Bacteria, as Archaea and Eucarya use various unrelated or “nonhomologous” proteins for energy and metabolic balance. The present study focuses on PPK1 and PPK2 homologues, which have been described to some extent in Bacteria, and the aim was to determine which homologue group, PPK1 or PPK2, is older. Phylogenetic analyses of 109 sequence homologues of Escherichia coli PPK1 and 109 sequence homologues of Pseudomonas aeruginosa PPK2 from 109 bacterial genomes imply that polyphosphate consumption (PPK2) evolved first and that phosphate polymerisation (PPK1) evolved later. Independently, a theory of the trends in amino acid loss and gain also confirms that PPK2 is older than PPK1. According to the results of this study, we propose 68 hypothetical proteins to mark as PPK2 homologues and 3 hypothetical proteins to mark as PPK1 homologues.

The Many Roads to Cell Death: Gaining a Practical Understanding of Apoptosis, Necrosis, and Autophagy

Science ◽  
2014 ◽  
Vol 344 (6187) ◽  
pp. 1048-1048
Author(s):  
J. Abrams ◽  
W. G. Telford
Keyword(s):  
Cell Death ◽  
The Many
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