Molecular mechanism of SbmA, a promiscuous transporter exploited by antimicrobial peptides.
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ABSTRACT:
SUBMITTER: Ghilarov D
PROVIDER: S-EPMC8442886 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:In view of increasing health threats from multiresistant pathogens, antimicrobial peptides (AMPs) and, specifically, proline-rich AMPs (PrAMPs) have been investigated in animal models. PrAMPs enter bacteria via the ABC transporter SbmA and inhibit intracellular targets. We used phage transduction (Tn10 insertion) to screen by random mutagenesis for alternative uptake mechanisms for analogs of apidaecin 1b, a honeybee-derived PrAMP. All 24 apidaecin-resistant mutants had the Tn10 insertion in the sbmA gene. These sbmA::Tn10 insertion mutants and the Escherichia coli BW25113 ?sbmA (JW0368) strain were still susceptible to the bactenecin PrAMP Bac7(1-35) and oncocin PrAMPs Onc18 and Onc112, as well as to Chex1-Arg20, despite significantly reduced internalizations. In a second round of random mutagenesis, the remaining susceptibility was linked to the yjiL-mdtM gene cluster. E. coli BW25113 and its ?yjiL null mutant (JW5785) were equally susceptible to all PrAMPs tested, whereas the BW25113 ?mdtM mutant was less susceptible to oncocins. The JW0368 yjiL::Tn10 transposon mutant (BS2) was resistant to all short PrAMPs and susceptible only to full-length Bac7 and A3-APO. Interestingly, PrAMPs appear to enter bacteria via MdtM, a multidrug resistance transporter (drug/H(+) antiporter) of the major facilitator superfamily (MFS) that can efflux antibiotics, biocides, and bile salts. In conclusion, PrAMPs enter bacteria via ABC and MFS transporters that efflux antibiotics and cytotoxic compounds from the cytoplasm to the periplasm.
| S-EPMC4576061 | biostudies-literature
Project description:PGLa and magainin 2 (MAG2) are amphiphilic ?-helical membranolytic peptides from frog skin with known synergistic antimicrobial activity. By systematically mutating residues in the two peptides it was possible to identify the ones crucial for the synergy, as monitored by biological assays, fluorescence vesicle leakage, and solid-state 15N-NMR. Electrostatic interactions between anionic groups in MAG2 and cationic residues in PGLa enhance synergy but are not necessary for the synergistic effect. Instead, two Gly residues (7 and 11) in a so-called GxxxG motif in PGLa are necessary for synergy. Replacing either of them with Ala or another hydrophobic residue completely abolishes synergy according to all three methods used. The designer-made peptide MSI-103, which has a similar sequence as PGLa, shows no synergy with MAG2, but by introducing two Gly mutations it was possible to make it synergistic. A molecular model is proposed for the functionally active PGLa-MAG2 complex, consisting of a membrane-spanning antiparallel PGLa dimer that is stabilized by intimate Gly-Gly contacts, and where each PGLa monomer is in contact with one MAG2 molecule at its C-terminus.
| S-EPMC5640672 | biostudies-literature
Project description:SbmA is an inner membrane protein of Gram-negative bacteria that is involved in the internalization of glycopeptides and prokaryotic and eukaryotic antimicrobial peptides, as well as of peptide nucleic acid (PNA) oligomers. The SbmA homolog BacA is required for the development of Sinorhizobium meliloti bacteroids within plant cells and favors chronic infections with Brucella abortus and Mycobacterium tuberculosis in mice. Here, we investigated functional features of SbmA/BacA using the proline-rich antimicrobial peptide Bac7(1-35) as a substrate. Circular dichroism and affinity chromatography studies were used to investigate the ability of SbmA to bind the peptide, and a whole-cell transport assay with fluorescently labeled peptide allowed the determination of transport kinetic parameters with a calculated Km value of 6.95 ± 0.89 μM peptide and a Vmax of 53.91 ± 3.17 nmol/min/mg SbmA. Use of a bacterial two-hybrid system coupled to SEC-MALLS (size exclusion chromatography coupled with multiangle laser light scattering) analyses established that SbmA is a homodimer in the membrane, and treatment of the cells with arsenate or ionophores indicated that the peptide transport mediated by SbmA is driven by the electrochemical gradient. Overall, these results shed light on the SbmA-mediated internalization of peptide substrates and suggest that the transport of an unknown substrate(s) represents the function of this protein.
| S-EPMC3837949 | biostudies-literature
Project description: Not available
| EMPIAR-10763 | biostudies-other
Project description:This SuperSeries is composed of the SubSeries listed below.
2018-09-15 | GSE113347 | GEO
Project description:The management of bacterial infections is becoming a major clinical challenge due to the rapid evolution of antibiotic resistant bacteria. As an excellent candidate to overcome antibiotic resistance, antimicrobial peptides (AMPs) that are produced from the synthetic and natural sources demonstrate a broad-spectrum antimicrobial activity with the high specificity and low toxicity. These peptides possess distinctive structures and functions by employing sophisticated mechanisms of action. This comprehensive review provides a broad overview of AMPs from the origin, structural characteristics, mechanisms of action, biological activities to clinical applications. We finally discuss the strategies to optimize and develop AMP-based treatment as the potential antimicrobial and anticancer therapeutics.
| S-EPMC8425997 | biostudies-literature
Project description:Antibiotic-resistant bacteria are recognized as one of the leading causes of death in the world. We proposed and successfully tested peptides with a new mechanism of antimicrobial action "protein silencing" based on directed co-aggregation. The amyloidogenic antimicrobial peptide (AAMP) interacts with the target protein of model or pathogenic bacteria and forms aggregates, thereby knocking out the protein from its working condition. In this review, we consider antimicrobial effects of the designed peptides on two model organisms, E. coli and T. thermophilus, and two pathogenic organisms, P. aeruginosa and S. aureus. We compare the amino acid composition of proteomes and especially S1 ribosomal proteins. Since this protein is inherent only in bacterial cells, it is a good target for studying the process of co-aggregation. This review presents a bioinformatics analysis of these proteins. We sum up all the peptides predicted as amyloidogenic by several programs and synthesized by us. For the four organisms we studied, we show how amyloidogenicity correlates with antibacterial properties. Let us especially dwell on peptides that have demonstrated themselves as AMPs for two pathogenic organisms that cause dangerous hospital infections, and in which the minimal inhibitory concentration (MIC) turned out to be comparable to the MIC of gentamicin sulfate. All this makes our study encouraging for the further development of AAMP. The hybrid peptides may thus provide a starting point for the antibacterial application of amyloidogenic peptides.
| S-EPMC9140876 | biostudies-literature
Project description:Spinal and bulbar muscular atrophy (SBMA) is a neuromuscular disease caused by a polyglutamine (polyQ) expansion in the androgen receptor (AR). Despite the fact that the monogenic cause of SBMA has been known for nearly 3 decades, there is no effective treatment for this disease, underscoring the complexity of the pathogenic mechanisms that lead to a loss of motor neurons and muscle in SBMA patients. In the current review, we provide an overview of the system-wide clinical features of SBMA, summarize the structure and function of the AR, discuss both gain-of-function and loss-of-function mechanisms of toxicity caused by polyQ-expanded AR, and describe the cell and animal models utilized in the study of SBMA. Additionally, we summarize previously conducted clinical trials which, despite being based on positive results from preclinical studies, proved to be largely ineffective in the treatment of SBMA; nonetheless, these studies provide important insights as researchers develop the next generation of therapies.
| S-EPMC6985201 | biostudies-literature
Project description:BackgroundWith the development of bacterial resistance, the range of effective antibiotics is increasingly becoming more limited. The effective use of nanoscale antimicrobial peptides (AP) in therapeutic and diagnostic methods is a strategy for new antibiotics.MethodsCombining both AP and cadmium selenide (CdSe) into a composite material may result in a reagent with novel properties, such as enhanced antibacterial activity, fluorescence and favorable stability in aqueous solution.ResultsAP-loaded CdSe NPs (AP-CdSe NPs) showed strong antibacterial activity against multidrug-resistant (MDR) Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) in vitro and in vivo. Colony-forming unit (CFU) and minimum inhibitory concentration (MIC) assays showed that AP-CdSe NPs have highly effective antibacterial activity. The quantitative analysis of apoptosis by flow cytometry analysis further confirmed that MDR E. coli and S. aureus treated with AP-CdSe NPs had death rates of 98.76% and 99.13%, respectively. Also, AP-CdSe NPs was found to inhibit bacterial activity in an in vivo bacteremia model in mice infected with S. aureus. In addition, the antibacterial mechanism of AP-CdSe NPs was determined by RNA sequencing analysis. Gene ontology (GO) analysis and Kyoto encyclopedia of genes and genomes (KEGG) pathway analysis revealed the molecular mechanism of the antibacterial effect of AP-CdSe NPs. Importantly, histopathology analysis, and hematological toxicity analysis indicated that AP-CdSe NPs had few side effects.ConclusionThese results demonstrate that AP loaded on CdSe NPs had a higher water solubility, bioavailability and antibacterial effect compared with raw AP. This study reports findings that are helpful for the design and development of antibacterial treatment strategies based on AP.
| S-EPMC7943780 | biostudies-literature
Project description: Not available
| EMPIAR-10777 | biostudies-other