Efficient extracellular laccase secretion via bio-designed secretory apparatuses to enhance bacterial utilization of recalcitrant lignin

2021 ◽  
Author(s):  
Lanfang Cao ◽  
Lu Lin ◽  
Haiyan Sui ◽  
Heng Wang ◽  
Zhichao Zhang ◽  
...  
Keyword(s):  
Bacterial Cell ◽  
Gram Negative Bacteria ◽  
Cell Systems ◽  
Gram Negative ◽  
Extracellular Laccase ◽  
Bacterial Utilization ◽  
Lignin Utilization

Our study advances the knowledge of secretion mechanisms in Gram-negative bacteria and provides novel insights into the lignin utilization by extracellular lignolytic enzyme-bacterial cell systems.

scholarly journals The ColM Family, Polymorphic Toxins Breaching the Bacterial Cell Wall

mBio ◽  
2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Maarten G. K. Ghequire ◽  
Susan K. Buchanan ◽  
René De Mot
Keyword(s):  
Cell Wall ◽  
Bacterial Cell ◽  
Cytoplasmic Membrane ◽  
Catalytic Domain ◽  
Gram Negative Bacteria ◽  
Antibacterial Peptides ◽  
Gram Negative ◽  
Lipid Ii ◽  
Associated Proteins ◽  
Colicin M

ABSTRACT Bacteria host an arsenal of antagonism-mediating molecules to combat for ecologic space. Bacteriocins represent a pivotal group of secreted antibacterial peptides and proteins assisting in this fight, mainly eliminating relatives. Colicin M, a model for peptidoglycan-interfering bacteriocins in Gram-negative bacteria, appears to be part of a set of polymorphic toxins equipped with such a catalytic domain (ColM) targeting lipid II. Diversifying recombination has enabled parasitism of different receptors and has also given rise to hybrid bacteriocins in which ColM is associated with another toxin module. Remarkably, ColM toxins have recruited a diverse array of immunity partners, comprising cytoplasmic membrane-associated proteins with different topologies. Together, these findings suggest that different immunity mechanisms have evolved for ColM, in contrast to bacteriocins with nuclease activities.

scholarly journals Structure of a bacterial Rhs effector exported by the type VI secretion system

2021 ◽  
Author(s):  
Patrick Guenther ◽  
Dennis Quentin ◽  
Shehryar Ahmad ◽  
Kartik Sachar ◽  
Christos Gatsogiannis ◽  
...  
Keyword(s):  
Bacterial Cell ◽  
Secretion System ◽  
Effector Proteins ◽  
Protein Export ◽  
Spike Protein ◽  
Gram Negative Bacteria ◽  
Structural Elements ◽  
Type Vi Secretion System ◽  
Gram Negative ◽  
Type Vi Secretion

The type VI secretion system (T6SS) is a widespread protein export apparatus found in Gram-negative bacteria. The majority of T6SSs deliver toxic effector proteins into competitor bacteria. Yet, the structure, function, and activation of many of these effectors remains poorly understood. Here, we present the structures of the T6SS effector RhsA from Pseudomonas protegens and its cognate T6SS spike protein, VgrG1, at 3.3 Å resolution. The structures reveal that the rearrangement hotspot (Rhs) repeats of RhsA assemble into a closed anticlockwise β-barrel spiral similar to that found in bacterial insecticidal Tc toxins and in metazoan teneurin proteins. We find that the C-terminal toxin domain of RhsA is autoproteolytically cleaved but remains inside the Rhs ′cocoon′ where, with the exception of three ordered structural elements, most of the toxin is disordered. The N-terminal ′plug′ domain is unique to T6SS Rhs proteins and resembles a champagne cork that seals the Rhs cocoon at one end while also mediating interactions with VgrG1. Interestingly, this domain is also autoproteolytically cleaved inside the cocoon but remains associated with it. We propose that mechanical force is required to remove the cleaved part of the plug, resulting in the release of the toxin domain as it is delivered into a susceptible bacterial cell by the T6SS.

scholarly journals Extracellular Vesicles: An Overlooked Secretion System in Cyanobacteria

Life ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 129 ◽  
Author(s):  
Steeve Lima ◽  
Jorge Matinha-Cardoso ◽  
Paula Tamagnini ◽  
Paulo Oliveira
Keyword(s):  
Extracellular Vesicles ◽  
Bacterial Cell ◽  
Cell Biology ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Formation Processes ◽  
Gram Negative ◽  
Nanoscale Structures ◽  
Membrane Components

In bacteria, the active transport of material from the interior to the exterior of the cell, or secretion, represents a very important mechanism of adaptation to the surrounding environment. The secretion of various types of biomolecules is mediated by a series of multiprotein complexes that cross the bacterial membrane(s), each complex dedicated to the secretion of specific substrates. In addition, biological material may also be released from the bacterial cell in the form of vesicles. Extracellular vesicles (EVs) are bilayered, nanoscale structures, derived from the bacterial cell envelope, which contain membrane components as well as soluble products. In cyanobacteria, the knowledge regarding EVs is lagging far behind compared to what is known about, for example, other Gram-negative bacteria. Here, we present a summary of the most important findings regarding EVs in Gram-negative bacteria, discussing aspects of their composition, formation processes and biological roles, and highlighting a number of technological applications tested. This lays the groundwork to raise awareness that the release of EVs by cyanobacteria likely represents an important, and yet highly disregarded, survival strategy. Furthermore, we hope to motivate future studies that can further elucidate the role of EVs in cyanobacterial cell biology and physiology.

scholarly journals A multifunctional platform with single-NIR-laser-triggered photothermal and NO release for synergistic therapy against multidrug-resistant Gram-negative bacteria and their biofilms

2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Baohua Zhao ◽  
He Wang ◽  
Wenjing Dong ◽  
Shaowen Cheng ◽  
Haisheng Li ◽  
...  
Keyword(s):  
Cell Membrane ◽  
Bacterial Cell ◽  
Multidrug Resistant ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
No Release ◽  
Bacterial Cell Membrane ◽  
Multifunctional Platform ◽  
Nir Laser

Abstract Background Infectious diseases caused by multidrug-resistant (MDR) bacteria, especially MDR Gram-negative strains, have become a global public health challenge. Multifunctional nanomaterials for controlling MDR bacterial infections via eradication of planktonic bacteria and their biofilms are of great interest. Results In this study, we developed a multifunctional platform (TG-NO-B) with single NIR laser-triggered PTT and NO release for synergistic therapy against MDR Gram-negative bacteria and their biofilms. When located at the infected sites, TG-NO-B was able to selectively bind to the surfaces of Gram-negative bacterial cells and their biofilm matrix through covalent coupling between the BA groups of TG-NO-B and the bacterial LPS units, which could greatly improve the antibacterial efficiency, and reduce side damages to ambient normal tissues. Upon single NIR laser irradiation, TG-NO-B could generate hyperthermia and simultaneously release NO, which would synergistically disrupt bacterial cell membrane, further cause leakage and damage of intracellular components, and finally induce bacteria death. On one hand, the combination of NO and PTT could largely improve the antibacterial efficiency. On the other hand, the bacterial cell membrane damage could improve the permeability and sensitivity to heat, decrease the photothermal temperature and avoid damages caused by high temperature. Moreover, TG-NO-B could be effectively utilized for synergistic therapy against the in vivo infections of MDR Gram-negative bacteria and their biofilms and accelerate wound healing as well as exhibit excellent biocompatibility both in vitro and in vivo. Conclusions Our study demonstrates that TG-NO-B can be considered as a promising alternative for treating infections caused by MDR Gram-negative bacteria and their biofilms.

Bacterial cell damage by the complement system of channel catfish, Ictalurus punctatus

1987 ◽  
Vol 45 ◽  
pp. 888-889
Author(s):  
Rosemarie Rosell-Davis ◽  
Jill A. Jenkins ◽  
Lewis B. Coons ◽  
Donald D. Ourth
Keyword(s):  
Ictalurus Punctatus ◽  
Complement System ◽  
Channel Catfish ◽  
Bacterial Cell ◽  
Cell Damage ◽  
Membrane Attack Complex ◽  
Gram Negative Bacteria ◽  
Bacterial Cells ◽  
Gram Negative ◽  
The Complement System

The alternative complement pathway (ACP) provides the non-immune channel catfish with protection against many Gram-negative bacteria. The role of serum complement against Gram-negative bacteria is death of cells by insertion of the membrane attack complex (C5b-9) into the cell membrane. The assembly of the membrane attack complex is generated by the ACP and is activated by bacterial cell wall components. Pseudomonas fluorescens is a pathogen of channel catfish. In this study, bacteria were examined after incubation with catfish serum by scanning and transmission electron microscopy (SEM and TEM) for ultrastructural evidence of cell envelope damage by the complement system.A percent bactericidal assay determined that catfish plasma was 99% bactericidal against a 24 h culture of P. fluorescens (ATCC 13525). Following a 1 h incubation at 30°C of bacterial dilutions with equal volumes of serum, heat-inactivated serum, zymosan-adsorbed serum, or saline, the bacterial cells were filtered onto 0.22 um nuclepore filters, fixed in glutaraldehyde, dehydrated in ethanol, critical point dried, sputter coated with 15 nm gold and imaged using a JEOL SEM.

scholarly journals Structure of a bacterial Rhs effector exported by the type VI secretion system

2022 ◽  
Vol 18 (1) ◽  
pp. e1010182
Author(s):  
Patrick Günther ◽  
Dennis Quentin ◽  
Shehryar Ahmad ◽  
Kartik Sachar ◽  
Christos Gatsogiannis ◽  
...  
Keyword(s):  
Bacterial Cell ◽  
Secretion System ◽  
Effector Proteins ◽  
Protein Export ◽  
Spike Protein ◽  
Gram Negative Bacteria ◽  
Structural Elements ◽  
Type Vi Secretion System ◽  
Gram Negative ◽  
Type Vi Secretion

The type VI secretion system (T6SS) is a widespread protein export apparatus found in Gram-negative bacteria. The majority of T6SSs deliver toxic effector proteins into competitor bacteria. Yet, the structure, function, and activation of many of these effectors remains poorly understood. Here, we present the structures of the T6SS effector RhsA from Pseudomonas protegens and its cognate T6SS spike protein, VgrG1, at 3.3 Å resolution. The structures reveal that the rearrangement hotspot (Rhs) repeats of RhsA assemble into a closed anticlockwise β-barrel spiral similar to that found in bacterial insecticidal Tc toxins and in metazoan teneurin proteins. We find that the C-terminal toxin domain of RhsA is autoproteolytically cleaved but remains inside the Rhs ‘cocoon’ where, with the exception of three ordered structural elements, most of the toxin is disordered. The N-terminal ‘plug’ domain is unique to T6SS Rhs proteins and resembles a champagne cork that seals the Rhs cocoon at one end while also mediating interactions with VgrG1. Interestingly, this domain is also autoproteolytically cleaved inside the cocoon but remains associated with it. We propose that mechanical force is required to remove the cleaved part of the plug, resulting in the release of the toxin domain as it is delivered into a susceptible bacterial cell by the T6SS.

PHLORETIN: AN ANTIBACTERIAL SUBSTANCE OBTAINED FROM APPLE LEAVES

1952 ◽  
Vol 30 (4) ◽  
pp. 486-489 ◽  
Author(s):  
Russell E. MacDonald ◽  
Charles J. Bishop
Keyword(s):  
Bacterial Cell ◽  
Antibacterial Action ◽  
Gram Negative Bacteria ◽  
Antibacterial Substance ◽  
Gram Positive ◽  
Gram Negative ◽  
Apple Leaves

A crystalline antibacterial substance isolated from apple leaves has been identified as phloretin. It has been shown to inhibit the growth of a number of Gram-positive and Gram-negative bacteria. The activity of the compound is bacteriostatic in nature and is shown in concentrations as low as 30 p.p.m. Its antibacterial action may be related to inhibition of the uptake of phosphorus by the bacterial cell.

Bacterial cell division is involved in the damage of gram-negative bacteria on a nano-pillar titanium surface

2018 ◽  
Vol 4 (5) ◽  
pp. 055002 ◽  
Author(s):  
Manfred Köller ◽  
Nadine Ziegler ◽  
Christina Sengstock ◽  
Thomas A Schildhauer ◽  
Alfred Ludwig
Keyword(s):  
Cell Division ◽  
Bacterial Cell ◽  
Titanium Surface ◽  
Gram Negative Bacteria ◽  
Bacterial Cell Division ◽  
Gram Negative

Infectious disease

2019 ◽  
Author(s):  
Stevan R. Emmett ◽  
Nicola Hill ◽  
Federico Dajas-Bailador
Keyword(s):  
Cell Wall ◽  
Protein Synthesis ◽  
Nucleic Acid ◽  
Outer Membrane ◽  
Bacterial Cell ◽  
Bacterial Cell Wall ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Antibiotics include an extensive range of agents able to kill or prevent reproduction of bacteria in the body, without being overly toxic to the patient. Traditionally derived from living organisms, most are now chemically synthesized and act to disrupt the integrity of the bacterial cell wall, or penetrate the cell and disrupt protein synthesis or nucleic acid replication. Typically, bacteria are identified according to their ap­pearance under the microscope depending on shape and response to the Gram stain test. Further identification is obtained by growth characteristics on various types of culture media, based on broth or agar, biochemical and immunological profiles. Further testing on broth or agar determines antibiotic sensitivity to guide on anti­biotic therapy in individual patients. This process can take 24– 48 hours to culture and a further 24– 48 hours to measure sensitivities. Increasingly, new technology, e.g. Matrix Assisted Laser Desorption Ionization— Time of Flight (MALDI- TOF) and nucleic acid amplification as­says, are being used to provide more rapid identification. The Gram classification, however, is still widely referred to as it differentiates bacteria by the presence or absence of the outer lipid membrane (see Figure 11.1), a fundamental characteristic that influences antibiotic management. Antimicrobial agents rely on selective action exploiting genetic differences between bacterial and eukaryotic cells. They target bacterial cell wall synthesis, bacterial protein synthesis, microbial DNA or RNA synthesis, by acting on bacterial cell metabolic pathways or by inhibiting the ac­tion of a bacterial toxin (see Table 11.1). Both Gram- positive and Gram- negative bacteria possess a rigid cell wall able to protect the bacteria from varying osmotic pressures (Figure 11.1). Peptidoglycan gives the cell wall its rigidity and is composed of a glycan chain of complex alternating carbohydrates, N- acetylglucosamide (N- ATG), and N- acetylmurcarinic acid (N- ATM), that are cross- linked by peptide (or glycine) chains. In Gram-positive bacteria, the cell wall contains multiple peptido­glycan layers, interspersed with teichoic acids, whereas Gram- negative bacteria contain only one or two peptido­glycan layers that are surrounded by an outer membrane attached by lipoproteins. The outer membrane contains porins (which regulate transport of substances into and out of the cell), lipopolysaccharides, and outer proteins in a phospholipid bilayer. For both Gram- negative and Gram-positive bacteria, peptidoglycan synthesis involves about 30 bacterial enzymes acting over three stages. Since the cell wall is unique to bacteria, it makes a suitable target for antibiotic therapy.

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