scholarly journals Structure and lipid dynamics in the maintenance of lipid asymmetry inner membrane complex of A. baumannii

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Daniel Mann ◽  
Junping Fan ◽  
Kamolrat Somboon ◽  
Daniel P. Farrell ◽  
Andrew Muenks ◽  
...  
Keyword(s):  
Bound States ◽  
Modern Medicine ◽  
Lipid Binding ◽  
Lipid Transport ◽  
Resistant Bacteria ◽  
Lipid Asymmetry ◽  
Gram Negative ◽  
The Core ◽  
Membrane Complex ◽  
Lipid Dynamics

AbstractMulti-resistant bacteria are a major threat in modern medicine. The gram-negative coccobacillus Acinetobacter baumannii currently leads the WHO list of pathogens in critical need for new therapeutic development. The maintenance of lipid asymmetry (MLA) protein complex is one of the core machineries that transport lipids from/to the outer membrane in gram-negative bacteria. It also contributes to broad-range antibiotic resistance in several pathogens, most prominently in A. baumannii. Nonetheless, the molecular details of its role in lipid transport has remained largely elusive. Here, we report the cryo-EM maps of the core MLA complex, MlaBDEF, from the pathogen A. baumannii, in the apo-, ATP- and ADP-bound states, revealing multiple lipid binding sites in the cytosolic and periplasmic side of the complex. Molecular dynamics simulations suggest their potential trajectory across the membrane. Collectively with the recently-reported structures of the E. coli orthologue, this data also allows us to propose a molecular mechanism of lipid transport by the MLA system.

scholarly journals Structure and lipid dynamics in the A. baumannii maintenance of lipid asymmetry (MLA) inner membrane complex

2020 ◽  
Author(s):  
Daniel Mann ◽  
Junping Fan ◽  
Daniel P. Farrell ◽  
Kamolrat Somboon ◽  
Andrew Muenks ◽  
...  
Keyword(s):  
Bound States ◽  
Modern Medicine ◽  
Lipid Binding ◽  
Lipid Transport ◽  
Resistant Bacteria ◽  
Lipid Asymmetry ◽  
Gram Negative ◽  
The Core ◽  
Membrane Complex ◽  
Lipid Dynamics

AbstractMulti-resistant bacteria are a major threat in modern medicine. The gram-negative coccobacillus Acinetobacter baumannii currently leads the WHO list of pathogens in critical need for new therapeutic development. The maintenance of lipid asymmetry (MLA) protein complex is one of the core machineries that transport lipids from/to the outer membrane in gram-negative bacteria. It also contributes to broad-range antibiotic resistance in several pathogens, most prominently in A. baumannii. Nonetheless, the molecular details of its role in lipid transport has remained largely elusive.Here, we report the cryo-EM structures of the core MLA complex, MlaBDEF, from the pathogen A. baumannii, in the apo-, ATP- and ADB-bound states. These structures reveal multiple lipid binding sites, in the cytosolic and periplasmic side of the complex. Molecular dynamics simulations suggest their potential trajectory across the membrane. Collectively with the recently-reported structures of the E.coli orthologue, these data also allows us to propose a molecular mechanism of lipid transport by the MLA system.

scholarly journals Intermembrane transport: Glycerophospholipid homeostasis of the Gram-negative cell envelope

2019 ◽  
Vol 116 (35) ◽  
pp. 17147-17155 ◽  
Author(s):  
Matthew J. Powers ◽  
M. Stephen Trent
Keyword(s):  
Outer Membrane ◽  
Bacterial Cell ◽  
Cell Envelope ◽  
Lipid Transport ◽  
Lipid Asymmetry ◽  
Gram Negative ◽  
Outer Membranes ◽  
Negative Cell ◽  
Initial Discovery ◽  
Structural Methods

This perspective addresses recent advances in lipid transport across the Gram-negative inner and outer membranes. While we include a summary of previously existing literature regarding this topic, we focus on the maintenance of lipid asymmetry (Mla) pathway. Discovered in 2009 by the Silhavy group [J. C. Malinverni, T. J. Silhavy, Proc. Natl. Acad. Sci. U.S.A. 106, 8009–8014 (2009)], Mla has become increasingly appreciated for its role in bacterial cell envelope physiology. Through the work of many, we have gained an increasingly mechanistic understanding of the function of Mla via genetic, biochemical, and structural methods. Despite this, there is a degree of controversy surrounding the directionality in which Mla transports lipids. While the initial discovery and subsequent studies have posited that it mediated retrograde lipid transport (removing glycerophospholipids from the outer membrane and returning them to the inner membrane), others have asserted the opposite. This Perspective aims to lay out the evidence in an unbiased, yet critical, manner for Mla-mediated transport in addition to postulation of mechanisms for anterograde lipid transport from the inner to outer membranes.

scholarly journals Peptides affecting outer membrane lipid asymmetry (MlaA-OmpC/F) system reduce avian pathogenic Escherichia coli (APEC) colonization in chickens

2021 ◽  
Author(s):  
Dipak Kathayat ◽  
Gary Closs ◽  
Yosra A. Helmy ◽  
Dhanashree Lokesh ◽  
Sochina Ranjit ◽  
...  
Keyword(s):  
Antimicrobial Peptides ◽  
Outer Membrane ◽  
Effective Control ◽  
Neonatal Meningitis ◽  
Resistant Bacteria ◽  
Lipid Asymmetry ◽  
Gram Negative ◽  
E Coli ◽  
Tract Infections ◽  
F System

Avian pathogenic E. coli (APEC), an extra-intestinal pathogenic E. coli (ExPEC), causes colibacillosis in chickens and is reportedly associated with urinary tract infections and meningitis in humans. Development of resistance is a major limitation of current ExPEC antibiotic therapy. New antibacterials that can circumvent resistance problem such as antimicrobial peptides (AMPs) are critically needed. Here, we evaluated the efficacy of Lactobacillus rhamnosus GG (LGG) derived peptides against APEC and uncovered their potential antibacterial targets. Three peptides (NPSRQERR: P1; PDENK: P2, and VHTAPK: P3) displayed inhibitory activity against APEC. These peptides were effective against APEC in biofilm and chicken macrophage HD11 cells. Treatment with these peptides reduced the cecum colonization (0.5 to 1.3 logs) of APEC in chickens. Microbiota analysis revealed two peptides (P1 and P2) decreased Enterobacteriaceae abundance with minimal impact on overall cecal microbiota of chickens. Bacterial cytological profiling showed peptides disrupt APEC membrane either by causing membrane shedding, rupturing or flaccidity. Further, gene expression analysis revealed that peptides downregulated the expression of omp C (>13.0 folds), omp F (>11.3 folds) and mla A (>4.9 folds) genes responsible for maintenance of outer membrane (OM) lipid asymmetry. Consistently, immunoblot analysis also showed decreased levels of OmpC and MlaA proteins in APEC treated with peptides. Alanine scanning studies revealed residues crucial (P1: N, E, R and P; P2: D and E; P3: T, P, and K) for their activity. Overall, our study identified peptides with new antibacterial target that can be developed to control APEC infections in chickens, thereby curtailing poultry-originated human ExPEC infections. Importance APEC is a subgroup of ExPEC and considered as a foodborne zoonotic pathogen transmitted through consumption of contaminated poultry products. APEC shares genetic similarities with human ExPECs, including uropathogenic E. coli (UPEC) and neonatal meningitis E. coli (NMEC). Our study identified LGG-derived peptides (P1: NPSRQERR, P2: PDENK, and P3: VHTAPK) effective in reducing APEC infection in chickens. Antimicrobial peptides (AMPs) are regarded as ideal candidates for antibacterial development because of their low propensity for resistance development and ability to kill resistant bacteria. Mechanistic studies showed peptides disrupt APEC membrane by affecting MlaA-OmpC/F system responsible for maintenance of OM lipid asymmetry, a promising new druggable target to overcome resistance problem in Gram-negative bacteria. Altogether, these peptides can provide a valuable approach for development of novel anti-ExPEC therapies, including APEC, human ExPECs and other related Gram-negative pathogens. Further, effective control of APEC infections in chickens can curb poultry-originated ExPEC infections in humans.

Lipid dynamics in the annexin V - membrane complex

1999 ◽  
Vol 96 (9/10) ◽  
pp. 1602-1607
Author(s):  
O. Saurel ◽  
P. Demange ◽  
A. Lopez ◽  
A. Milon
Keyword(s):  
Annexin V ◽  
Membrane Complex ◽  
Lipid Dynamics

scholarly journals The antimicrobial potential of cannabidiol

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Mark A. T. Blaskovich ◽  
Angela M. Kavanagh ◽  
Alysha G. Elliott ◽  
Bing Zhang ◽  
Soumya Ramu ◽  
...  
Keyword(s):  
Bacterial Infections ◽  
Modern Medicine ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
New Class ◽  
Clostridioides Difficile ◽  
Excellent Activity ◽  
Induce Resistance ◽  
First Time

AbstractAntimicrobial resistance threatens the viability of modern medicine, which is largely dependent on the successful prevention and treatment of bacterial infections. Unfortunately, there are few new therapeutics in the clinical pipeline, particularly for Gram-negative bacteria. We now present a detailed evaluation of the antimicrobial activity of cannabidiol, the main non-psychoactive component of cannabis. We confirm previous reports of Gram-positive activity and expand the breadth of pathogens tested, including highly resistant Staphylococcus aureus, Streptococcus pneumoniae, and Clostridioides difficile. Our results demonstrate that cannabidiol has excellent activity against biofilms, little propensity to induce resistance, and topical in vivo efficacy. Multiple mode-of-action studies point to membrane disruption as cannabidiol’s primary mechanism. More importantly, we now report for the first time that cannabidiol can selectively kill a subset of Gram-negative bacteria that includes the ‘urgent threat’ pathogen Neisseria gonorrhoeae. Structure-activity relationship studies demonstrate the potential to advance cannabidiol analogs as a much-needed new class of antibiotics.

scholarly journals Rapid Detection and Evaluation of Clinical Characteristics of Emerging Multiple-Drug-Resistant Gram-Negative Rods Carrying the Metallo-β-Lactamase GeneblaIMP

1998 ◽  
Vol 42 (8) ◽  
pp. 2006-2011 ◽  
Author(s):  
Yoichi Hirakata ◽  
Koichi Izumikawa ◽  
Toshiyuki Yamaguchi ◽  
Hiromu Takemura ◽  
Hironori Tanaka ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Rapid Detection ◽  
Clinical Characteristics ◽  
The Other ◽  
Resistant Bacteria ◽  
Multiple Drug ◽  
Drug Resistant ◽  
Gram Negative ◽  
Multiple Drug Resistant ◽  
Tract Infections

Gram-negative rods (GNR) carrying the transferable carbapenem resistance gene blaIMP, includingPseudomonas aeruginosa and Serratia marcescens, have been isolated from more than 20 hospitals in Japan. Although the emergence of such multiple-drug-resistant bacteria is of utmost clinical concern, little information in regard to the distribution ofblaIMP-positive GNR in hospitals and the clinical characteristics of infected patients is available. To address this, a system for the rapid detection of theblaIMP gene with a simple DNA preparation and by enzymatic detection of PCR products was developed. A total of 933 ceftazidime-resistant strains of GNR isolated between 1991 and 1996 at Nagasaki University Hospital, Nagasaki, Japan, were screened for theblaIMP gene; 80 isolates were positive, including 53 P. aeruginosa isolates, 13 other glucose-nonfermenting bacteria, 13 S. marcescens isolates, and 1 Citrobacter freundii isolate. Most of the patients from whom blaIMP-positive organisms were isolated had malignant diseases (53.8%). The organisms caused urinary tract infections, pneumonia, or other infections in 46.3% of the patients, while they were just colonizing the other patients evaluated. It was possible that blaIMP-positive P. aeruginosa strains contributed to the death of four patients, while the other infections caused by GNR carryingblaIMP were not lethal. DNA fingerprinting analysis by pulsed-field gel electrophoresis suggested the cross transmission of strains within the hospital. The isolates were ceftazidime resistant and were frequently resistant to other antibiotics. Although no particular means of pathogenesis ofblaIMP-positive GNR is evident at present, the rapid detection of such strains is necessary to help with infection control practices for the prevention of their dissemination and the transmission of the resistance gene to other pathogenic bacteria.

scholarly journals Multidrug-resistant bacteria isolated from surgical site of dogs, surgeon's hands and operating room in a veterinary teaching hospital in Brazil

2021 ◽  
Author(s):  
Mareliza Possa de Menezes ◽  
Mariana Borzi ◽  
Mayara Ruaro ◽  
Marita Cardozo ◽  
Fernando Ávila ◽  
...  
Keyword(s):  
Multidrug Resistant ◽  
High Rate ◽  
Resistant Bacteria ◽  
Coagulase Negative Staphylococci ◽  
Gram Negative ◽  
Source Of Infection ◽  
The One ◽  
Clean Contaminated ◽  
In The Beginning ◽  
Coagulase Positive Staphylococci

Abstract The aim of this study was to evaluate the prevalence and antimicrobial resistance profile of Gram-positive cocci and Gram-negative bacilli isolated from the surgical environment. All samples were collected during the intraoperative period of clean/clean-contaminated (G1) and contaminated (G2) surgery. A total of 150 samples were collected from the surgical wound in the beginning (n = 30) and end (n = 30) of the procedure, surgeon’s hands before (n = 30) and after (n = 30) antisepsis and the surgical environment (n = 30). Forty-three isolates with morphological and biochemical characteristics of Staphylococcus spp. and 13 of Gram-negative bacilli were obtained. Coagulase-negative staphylococci (85.71% [18/21]), coagulase-positive staphylococci (9.52% [2/21]) and Pseudomonas spp. (47.52% [1/21]) in G1, and coagulase-negative staphylococci (40% [14/35]), coagulase-positive staphylococci (20% [7/35]), Proteus spp. (17.14% [6/35]), E. coli (8.57% [3/35]), Pseudomonas spp. (2.86% [1/35]) and Salmonella spp. (2.86 [1/35]) in G2 were more frequently isolated, and a high incidence of multidrug resistance was observed in coagulase-negative staphylococci (87.5% [28/32]), coagulase-positive staphylococci (100% [11/11]) and Gram-negative bacilli (76.92% [10/13]). Methicillin-resistant Staphylococcus spp. accounted for 83.72% (36/43) of the Staphylococcus strains. Gram-negative bacilli cefotaxime-resistance constituted 81.82% (9/11) and imipenem resistance constituted 53.85% (7/13). The high rate of resistance of commensal bacteria found in our study is worrying. Coagulase-negative staphylococci are community pathogens related to nosocomial infections in human and veterinary hospitals, their presence in healthy patients and in veterinary professionals represent an important source of infection in the one health context. Continuous surveillance and application of antimicrobial stewardship programs are essential in the fight against this threat.

scholarly journals An overview of carbapenem, its resistance and therapeutic options for infections caused by carbapenem resistant bacteria

2020 ◽  
Vol 9 (9) ◽  
pp. 1454
Author(s):  
Hari P. Nepal ◽  
Rama Paudel
Keyword(s):  
Bacterial Infections ◽  
Carbapenem Resistance ◽  
Therapeutic Options ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Beta Lactam ◽  
Gram Negative ◽  
Penicillin Binding Proteins ◽  
Carbapenem Resistant ◽  
The World

Carbapenems are beta-lactam drugs that have broadest spectrum of activity. They are commonly used as the drugs of last resort to treat complicated bacterial infections. They bind to penicillin binding proteins (PBPs) and inhibit cell wall synthesis in bacteria. Important members that are in clinical use include doripenem, ertapenem, imipenem, and meropenem. Unlike other members, imipenem is hydrolyzed significantly by renal dehydropeptidase; therefore, it is administered together with an inhibitor of renal dehydropeptidase, cilastatin. Carbapenems are usually administered intravenously due to their low oral bioavailability. Most common side effects of these drugs include nausea, vomiting, diarrhea, skin rashes, and reactions at the infusion sites. Increasing resistance to these antibiotics is being reported throughout the world and is posing a threat to public health.  Primary mechanisms of carbapenem resistance include expulsion of drug and inactivation of the drug by production of carbapenemases which may not only hydrolyze carbapenem, but also cephalosporin, penicillin, and aztreonam. Resistance especially among Gram negative bacteria is of much concern since there are only limited therapeutic options available for infections caused by carbapenem resistant Gram-negative bacterial pathogens. Commonly used drugs to treat such infections include polymyxins, fosfomycin and tigecycline.

scholarly journals Metagenomic Assembly Reveals the Fate of the Core Antibiotic Resistome, its Hosts and Mobility in Animal Manure and After Compost

2021 ◽  
Author(s):  
Tianlei Qiu ◽  
Linhe Huo ◽  
Yajie Guo ◽  
Min Gao ◽  
Guoliang Wang ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Relative Abundance ◽  
Resistance Genes ◽  
Animal Manure ◽  
Procrustes Analysis ◽  
Resistant Bacteria ◽  
Broad Host Range ◽  
The Core ◽  
Metagenomic Assembly ◽  
Multidrug Resistance Genes

Abstract Background Antibiotics and antibiotic resistance genes (ARGs) used in intensive animal husbandry threaten human health worldwide; however, the core resistome, mobility of ARGs, and the composition of ARG hosts in animal manure and the following composts remain unclear. In the present study, metagenomic assembly was used to comprehensively decipher the core resistome and its potential mobility and hosts in animal manure and compost. Results In total, 201 ARGs were shared among different animal (layer, broiler, swine, beef cow, and dairy cow) manures and accounted for 86–99% of total relative abundance of ARGs, which mainly comprised multidrug, macrolide-lincosamide-streptogramin (M-L-S), tetracycline, beta-lactam, aminoglycoside, and sulfonamide resistance genes. Moreover, efficient composting reduced the total relative abundance of ARGs in manure from 0.938 to 0.405 copies per 16S rRNA gene; however, it did not have any remarkable effect on the multidrug, sulfonamide, and trimethoprim resistance genes. Procrustes analysis indicated that composting can reduce antibiotic residues and decrease the correlation between antibiotics and resistance genes. Furthermore, the ARG hosts included Proteobacteria (50.08%), Firmicutes (37.77%), Bacteroidetes (6.49%), and Actinobacteria (5.24%). In manure, aminoglycoside resistance genes were majorly found in Enterococcus, Streptococcus, and Enterobacter; tetracycline resistance genes (TRGs) were found in Pseudomonas, Lactobacillus, and Streptococcus; and multidrug resistance genes were mainly found in Escherichia coli. In our samples, ARGs were more prevalent in plasmids than in chromosomes. The broad host range and diverse mobile genetic elements may be two key factors for ARGs, such as sul1 and aadA, which could survive during composting. The multidrug resistance genes represented the dominant ARGs in pathogenic antibiotic-resistant bacteria (PARB) in manure, and composting could effectively control PARB. Conclusions Our experiments revealed the core resistome in animal manure, classified and relative quantified the ARG hosts, and assessed the mobility of ARGs. Composting can mitigate ARGs in animal manure by altering the bacterial hosts; however, some ARGs can escape from the removal with the survivor heat-tolerant hosts or transfer to these hosts. These findings will help optimize composting strategies for the effective treatment of ARGs and their hosts in farms.

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