scholarly journals BceAB-type antibiotic resistance transporters appear to act by target protection of cell wall synthesis

2019 ◽  
Author(s):  
Carolin M Kobras ◽  
Hannah Piepenbreier ◽  
Jennifer Emenegger ◽  
Andre Sim ◽  
Georg Fritz ◽  
...  
Keyword(s):  
Cell Wall ◽  
Antimicrobial Peptides ◽  
Gc Content ◽  
Critical Factor ◽  
Peptide Antibiotics ◽  
Cell Wall Synthesis ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Lipid Ii ◽  
High Level

ABSTRACTResistance against cell wall-active antimicrobial peptides in bacteria is often mediated by transporters. In low GC-content Gram-positive bacteria, a wide-spread type of such transporters are the BceAB-like systems, which frequently provide a high level of resistance against peptide antibiotics that target intermediates of the lipid II cycle of cell wall synthesis. How a transporter can offer protection from drugs that are active on the cell surface, however, has presented researchers with a conundrum. Multiple theories have been discussed, ranging from removal of the peptides from the membrane, internalisation of the drug for degradation, to removal of the cellular target rather than the drug itself. To resolve this much-debated question, we here investigated the mode of action of the transporter BceAB of Bacillus subtilis. We show that it does not inactivate or import its substrate antibiotic bacitracin. Moreover, we present evidence that the critical factor driving transport activity is not the drug itself, but instead the concentration of drug-target complexes in the cell. Our results, together with previously reported findings, lead us to propose that BceAB-type transporters act by transiently freeing lipid II cycle intermediates from the inhibitory grip of antimicrobial peptides, and thus provide resistance through target protection of cell wall synthesis. Target protection has so far only been reported for resistance against antibiotics with intracellular targets, such as the ribosome. However, this mechanism offers a plausible explanation for the use of transporters as resistance determinants against cell wall-active antibiotics in Gram-positive bacteria where cell wall synthesis lacks the additional protection of an outer membrane.

scholarly journals BceAB-Type Antibiotic Resistance Transporters Appear To Act by Target Protection of Cell Wall Synthesis

2019 ◽  
Vol 64 (3) ◽  
Author(s):  
Carolin M. Kobras ◽  
Hannah Piepenbreier ◽  
Jennifer Emenegger ◽  
Andre Sim ◽  
Georg Fritz ◽  
...  
Keyword(s):  
Cell Wall ◽  
Antimicrobial Peptides ◽  
Gc Content ◽  
Critical Factor ◽  
Peptide Antibiotics ◽  
Cell Wall Synthesis ◽  
Gram Positive ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Lipid Ii

ABSTRACT Resistance against cell wall-active antimicrobial peptides in bacteria is often mediated by transporters. In low-GC-content Gram-positive bacteria, a common type of such transporters is BceAB-like systems, which frequently provide high-level resistance against peptide antibiotics that target intermediates of the lipid II cycle of cell wall synthesis. How a transporter can offer protection from drugs that are active on the cell surface, however, has presented researchers with a conundrum. Multiple theories have been discussed, ranging from removal of the peptides from the membrane and internalization of the drug for degradation to removal of the cellular target rather than the drug itself. To resolve this much-debated question, we here investigated the mode of action of the transporter BceAB of Bacillus subtilis. We show that it does not inactivate or import its substrate antibiotic bacitracin. Moreover, we present evidence that the critical factor driving transport activity is not the drug itself but instead the concentration of drug-target complexes in the cell. Our results, together with previously reported findings, lead us to propose that BceAB-type transporters act by transiently freeing lipid II cycle intermediates from the inhibitory grip of antimicrobial peptides and thus provide resistance through target protection of cell wall synthesis. Target protection has so far only been reported for resistance against antibiotics with intracellular targets, such as the ribosome. However, this mechanism offers a plausible explanation for the use of transporters as resistance determinants against cell wall-active antibiotics in Gram-positive bacteria where cell wall synthesis lacks the additional protection of an outer membrane.

scholarly journals An Association Between Peptidoglycan Synthesis and Organization of the Streptococcus pyogenes ExPortal

mBio ◽  
2013 ◽  
Vol 4 (5) ◽  
Author(s):  
Luis Alberto Vega ◽  
Gary C. Port ◽  
Michael G. Caparon
Keyword(s):  
Cell Wall ◽  
Protein Secretion ◽  
Streptococcus Pyogenes ◽  
Secretory Pathway ◽  
Cell Wall Synthesis ◽  
Gram Positive ◽  
Content Type ◽  
Peptidoglycan Synthesis ◽  
Lipid Ii ◽  
Protein Components

ABSTRACTThe ExPortal ofStreptococcus pyogenesis a focal microdomain of the cytoplasmic membrane that clusters the translocons of the general secretory pathway with accessory factors to facilitate the maturation of secreted polypeptides. While it is known that the ExPortal is enriched in anionic lipids, the mechanisms that organize the ExPortal are poorly understood. In the present study, we examined the role of the cell wall in organizing and maintaining the ExPortal. Removal of the cell wall resulted in a loss of ExPortal focal integrity accompanied by the circumferential redistribution of ExPortal lipid and protein components. A similar loss occurred upon treatment with gallidermin, a nonpermeabilizing lantibiotic that targets the lipid II precursor of peptidoglycan synthesis, and this treatment disrupted the secretion of several ExPortal substrates. Furthermore, several enzymes involved in the membrane-associated steps of lipid II synthesis, including MraY and MurN, were found to localize to a single discrete focus in the membrane that was coincident with the focal location of the secretory translocons and the anionic lipid microdomain. These data suggest that the ExPortal is associated with the site of peptidoglycan precursor synthesis and that peptidoglycan biogenesis influences ExPortal organization. These data add to an emerging literature indicating that cell wall biogenesis, cell division, and protein secretion are spatially coorganized processes.IMPORTANCESince Gram-positive bacteria lack a periplasmic space, they lack a protected compartment to spatially coordinate interaction between newly secreted proteins and the factors required to process them. This represents a significant problem for pathogens that depend on the secretion of toxins and cell wall-associated adhesins to cause disease. Streptococci solve this dilemma by restricting secretion and processing factors to a defined region of the membrane. However, the mechanisms that promote restriction are not understood. In this study, we show that restriction of these factors in the pathogenStreptococcus pyogenesis intimately linked with the presence of the cell wall and its synthesis. Furthermore, several cell wall synthesis proteins are also restricted to the site of protein secretion. This study contributes to our understanding of how the Gram-positive cell is organized to coordinate protein secretion and biogenesis with cell wall synthesis and to the ongoing development of antibiotics that target these processes.

Antagonism by a Gram-positive coccus

1970 ◽  
Vol 16 (8) ◽  
pp. 661-665 ◽  
Author(s):  
T. J. Trust
Keyword(s):  
Cell Wall ◽  
Biological Properties ◽  
Cell Wall Synthesis ◽  
Gram Positive ◽  
Biochemical Characteristics ◽  
Gram Positive Bacteria ◽  
Solid Media ◽  
Positive Coccus

A Sarcina sp. has been isolated which is antagonistic to the growth of a number of Gram-positive bacteria when grown on solid media. The morphological and biochemical characteristics of the organism are described. The biological properties of the inhibitor have been examined. The data suggest that the inhibitor may interfere with cell wall synthesis.

scholarly journals Different subcellular locations of secretome components of Gram-positive bacteria

Microbiology ◽  
2006 ◽  
Vol 152 (10) ◽  
pp. 2867-2874 ◽  
Author(s):  
Girbe Buist ◽  
Anja N. J. A. Ridder ◽  
Jan Kok ◽  
Oscar P. Kuipers
Keyword(s):  
Cell Wall ◽  
Cytoplasmic Membrane ◽  
Secretion System ◽  
Transport Systems ◽  
Cell Wall Synthesis ◽  
Secretion Systems ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Different Types ◽  
Folded Proteins

Gram-positive bacteria contain different types of secretion systems for the transport of proteins into or across the cytoplasmic membrane. Recent studies on subcellular localization of specific components of these secretion systems and their substrates have shown that they can be present at various locations in the cell. The translocons of the general Sec secretion system in the rod-shaped bacterium Bacillus subtilis have been shown to localize in spirals along the cytoplasmic membrane, whereas the translocons in the coccoid Streptococcus pyogenes are located in a microdomain near the septum. In both bacteria the Sec translocons appear to be located near the sites of cell wall synthesis. The Tat secretion system, which is used for the transport of folded proteins, probably localizes in the cytoplasmic membrane and at the cell poles of B. subtilis. In Lactococcus lactis the ABC transporter dedicated to the transport of a small antimicrobial peptide is distributed throughout the membrane. Possible mechanisms for maintaining the localization of these secretion machineries involve their interaction with proteins of the cytoskeleton or components of the cell wall synthesis machinery, or the presence of lipid subdomains surrounding the transport systems.

scholarly journals Mechanism of Action of the Mannopeptimycins, a Novel Class of Glycopeptide Antibiotics Active against Vancomycin-Resistant Gram-Positive Bacteria

2004 ◽  
Vol 48 (3) ◽  
pp. 728-738 ◽  
Author(s):  
Alexey Ruzin ◽  
Guy Singh ◽  
Anatoly Severin ◽  
Youjun Yang ◽  
Russell G. Dushin ◽  
...  
Keyword(s):  
Cell Wall ◽  
Lipoteichoic Acid ◽  
Antimicrobial Activities ◽  
Cell Wall Biosynthesis ◽  
Glycopeptide Antibiotics ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Lipid Ii ◽  
Membrane Bound ◽  
Vancomycin Resistant

ABSTRACT The naturally occurring mannopeptimycins (formerly AC98-1 through AC98-5) are a novel class of glycopeptide antibiotics that are active against a wide variety of gram-positive bacteria. The structures of the mannopeptimycins suggested that they might act by targeting cell wall biosynthesis, similar to other known glycopeptide antibiotics; but the fact that the mannopeptimycins retain activity against vancomycin-resistant organisms suggested that they might have a unique mode of action. By using a radioactive mannopeptimycin derivative bearing a photoactivation ligand, it was shown that mannopeptimycins interact with the membrane-bound cell wall precursor lipid II [C55-MurNAc-(peptide)-GlcNAc] and that this interaction is different from the binding of other lipid II-binding antibiotics such as vancomycin and mersacidin. The antimicrobial activities of several mannopeptimycin derivatives correlated with their affinities toward lipid II, suggesting that the inhibition of cell wall biosynthesis was primarily through lipid II binding. In addition, it was shown that mannopeptimycins bind to lipoteichoic acid in a rather nonspecific interaction, which might facilitate the accumulation of antibiotic on the bacterial cell surface.

scholarly journals The dlt operon confers resistance to cationic antimicrobial peptides in Clostridium difficile

Microbiology ◽  
2011 ◽  
Vol 157 (5) ◽  
pp. 1457-1465 ◽  
Author(s):  
Shonna M. McBride ◽  
Abraham L. Sonenshein
Keyword(s):  
Cell Wall ◽  
Clostridium Difficile ◽  
Antimicrobial Peptides ◽  
Positive Charge ◽  
Polymyxin B ◽  
Gram Positive ◽  
Cationic Antimicrobial Peptides ◽  
Teichoic Acids ◽  
Gram Positive Bacteria ◽  
Net Positive Charge

The dlt operon in Gram-positive bacteria encodes proteins that are necessary for the addition of d-alanine to teichoic acids of the cell wall. The addition of d-alanine to the cell wall results in a net positive charge on the bacterial cell surface and, as a consequence, can decrease the effectiveness of antimicrobials, such as cationic antimicrobial peptides (CAMPs). Although the roles of the dlt genes have been studied for some Gram-positive organisms, the arrangement of these genes in Clostridium difficile and the life cycle of the bacterium in the host are markedly different from those of other pathogens. In the current work, we determined the contribution of the putative C. difficile dlt operon to CAMP resistance. Our data indicate that the dlt operon is necessary for full resistance of C. difficile to nisin, gallidermin, polymyxin B and vancomycin. We propose that the d-alanylation of teichoic acids provides protection against antimicrobial peptides that may be essential for growth of C. difficile in the host.

scholarly journals Increasing the Antimicrobial Activity of Nisin-Based Lantibiotics against Gram-Negative Pathogens

2018 ◽  
Vol 84 (12) ◽  
Author(s):  
Qian Li ◽  
Manuel Montalban-Lopez ◽  
Oscar P. Kuipers
Keyword(s):  
Antimicrobial Peptides ◽  
Outer Membrane ◽  
Rational Design ◽  
Bacterial Species ◽  
Gram Negative Bacteria ◽  
Gram Positive ◽  
Gram Negative ◽  
Content Type ◽  
Gram Positive Bacteria ◽  
Lipid Ii

ABSTRACTLantibiotics are ribosomally synthesized and posttranslationally modified antimicrobial compounds containing lanthionine and methyl-lanthionine residues. Nisin, one of the most extensively studied and used lantibiotics, has been shown to display very potent activity against Gram-positive bacteria, and stable resistance is rarely observed. By binding to lipid II and forming pores in the membrane, nisin can cause the efflux of cellular constituents and inhibit cell wall biosynthesis. However, the activity of nisin against Gram-negative bacteria is much lower than that against Gram-positive bacteria, mainly because lipid II is located at the inner membrane, and the rather impermeable outer membrane in Gram-negative bacteria prevents nisin from reaching lipid II. Thus, if the outer membrane-traversing efficiency of nisin could be increased, the activity against Gram-negative bacteria could, in principle, be enhanced. In this work, several relatively short peptides with activity against Gram-negative bacteria were selected from literature data to be fused as tails to the C terminus of either full or truncated nisin species. Among these, we found that one of three tails (tail 2 [T2; DKYLPRPRPV], T6 [NGVQPKY], and T8 [KIAKVALKAL]) attached to a part of nisin displayed improved activity against Gram-negative microorganisms. Next, we rationally designed and reengineered the most promising fusion peptides. Several mutants whose activity significantly outperformed that of nisin against Gram-negative pathogens were obtained. The activity of the tail 16 mutant 2 (T16m2) construct against several important Gram-negative pathogens (i.e.,Escherichia coli,Klebsiella pneumoniae,Acinetobacter baumannii,Pseudomonas aeruginosa,Enterobacter aerogenes) was increased 4- to 12-fold compared to that of nisin. This study indicates that the rational design of nisin can selectively and significantly improve its outer membrane-permeating capacity as well as its activity against Gram-negative pathogens.IMPORTANCELantibiotics are antimicrobial peptides that are highly active against Gram-positive bacteria but that have relatively poor activity against most Gram-negative bacteria. Here, we modified the model lantibiotic nisin by fusing parts of it to antimicrobial peptides with known activity against Gram-negative bacteria. The appropriate selection of peptidic moieties that could be attached to (parts of) nisin could lead to a significant increase in its inhibitory activity against Gram-negative bacteria. Using this strategy, hybrids that outperformed nisin by displaying 4- to 12-fold higher levels of activity against relevant Gram-negative bacterial species were produced. This study shows the power of modified peptide engineering to alter target specificity in a desired direction.

scholarly journals Nisin- and ripcin-derived hybrid lanthipeptides display selective antimicrobial activity against Staphylococcus aureus

2021 ◽  
Author(s):  
Xinghong Zhao ◽  
Oscar P. Kuipers
Keyword(s):  
Antimicrobial Activity ◽  
Cell Wall ◽  
Antimicrobial Peptides ◽  
Disulfide Bond ◽  
Bacterial Pathogens ◽  
Cell Wall Synthesis ◽  
Antibiotic Resistant ◽  
Gram Negative ◽  
Lipid Ii ◽  
Selective Antimicrobial Activity

Lanthipeptides are (methyl)lanthionine ring-containing ribosomally synthesized and post-translationally modified peptides (RiPPs). Many lanthipeptides show strong antimicrobial activity against bacterial pathogens, including antibiotic-resistant bacterial pathogens. The group of disulfide bond-containing antimicrobial peptides (AMPs) is well known in nature and forms a rich source of templates for the production of novel peptides with corresponding (methyl)lanthionine analogues instead of disulfides. Here, we show that novel macrocyclic lanthipeptides (termed thanacin and ripcin) can be synthesized using the known antimicrobials thanatin and rip-thanatin as templates. Notably, the synthesized nisin(1-20)-ripcin hybrid lanthipeptides (ripcin B-G) showed selective antimicrobial activity against S. aureus, including an antibiotic-resistant MRSA strain. Interestingly, ripcin B-G, which are hybrid peptides of nisin(1-20) and ripcin, respectively, that are each inactive against Gram-negative pathogens, showed substantial antimicrobial activity against the tested Gram-negative pathogens. Moreover, ripcin B-G was highly resistant against the nisin resistance protein (NSR; a protease could cleave nisin and strongly reduce its activity ), opposed to nisin itself. Mode of action studies show that ripcin C exerts its antimicrobial activity against Gram-positive pathogens by binding to the cell wall synthesis precursor lipid II and thereafter arrests cell growth. In addition, ripcin C exerts its antimicrobial activity against Gram-negative pathogens by binding to LPS and the cell wall synthesis precursor lipid II. This study provides an example of converting disulfide bond-based AMPs into (methyl)lanthionine-based macrocyclic hybrid lanthipeptides and can yield antimicrobial peptides with selective antimicrobial activity against S. aureus.

Influence of Cell Wall Composition on the Fossilisation of Bacteria and the Implications for the Search for Early Life Forms

1997 ◽  
Vol 161 ◽  
pp. 491-504 ◽  
Author(s):  
Frances Westall
Keyword(s):  
Cell Wall ◽  
Life Forms ◽  
Cation Binding ◽  
Positive Bacterium ◽  
Gram Positive ◽  
Gram Positive Bacteria ◽  
Transmission Electron ◽  
Hydrothermal Sediments ◽  
Identification Of Bacteria ◽  
The Difference

AbstractThe oldest cell-like structures on Earth are preserved in silicified lagoonal, shallow sea or hydrothermal sediments, such as some Archean formations in Western Australia and South Africa. Previous studies concentrated on the search for organic fossils in Archean rocks. Observations of silicified bacteria (as silica minerals) are scarce for both the Precambrian and the Phanerozoic, but reports of mineral bacteria finds, in general, are increasing. The problems associated with the identification of authentic fossil bacteria and, if possible, closer identification of bacteria type can, in part, be overcome by experimental fossilisation studies. These have shown that not all bacteria fossilise in the same way and, indeed, some seem to be very resistent to fossilisation. This paper deals with a transmission electron microscope investigation of the silicification of four species of bacteria commonly found in the environment. The Gram positiveBacillus laterosporusand its spore produced a robust, durable crust upon silicification, whereas the Gram negativePseudomonas fluorescens, Ps. vesicularis, andPs. acidovoranspresented delicately preserved walls. The greater amount of peptidoglycan, containing abundant metal cation binding sites, in the cell wall of the Gram positive bacterium, probably accounts for the difference in the mode of fossilisation. The Gram positive bacteria are, therefore, probably most likely to be preserved in the terrestrial and extraterrestrial rock record.

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