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Marine Drugs Jun 2024Sortase A (SrtA) is a cysteine transpeptidase that binds to the periplasmic membrane and plays a crucial role in attaching surface proteins, including staphylococcal...
Sortase A (SrtA) is a cysteine transpeptidase that binds to the periplasmic membrane and plays a crucial role in attaching surface proteins, including staphylococcal protein A (SpA), to the peptidoglycan cell wall. Six pentacyclic polyketides (-) were isolated from the marine sponge sp., and their structures were elucidated using spectroscopic techniques and by comparing them to previously reported data. Among them, halenaquinol () was found to be the most potent SrtA inhibitor, with an IC of 13.94 μM (4.66 μg/mL). Semi-quantitative reverse transcription PCR data suggest that halenaquinol does not inhibit the transcription of and , while Western blot analysis and immunofluorescence microscopy images suggest that it blocks the cell wall surface anchoring of SpA by inhibiting the activity of SrtA. The onset and magnitude of the inhibition of SpA anchoring on the cell wall surface in that has been treated with halenaquinol at a value 8× that of the IC of SrtA are comparable to those for an -deletion mutant. These findings contribute to the understanding of the mechanism by which marine-derived pentacyclic polyketides inhibit SrtA, highlighting their potential as anti-infective agents targeting virulence.
Topics: Aminoacyltransferases; Cysteine Endopeptidases; Staphylococcus aureus; Cell Wall; Bacterial Proteins; Animals; Porifera; Anti-Bacterial Agents; Polyketides
PubMed: 38921577
DOI: 10.3390/md22060266 -
Microbiology Spectrum Jun 2024Acetic acid bacteria are used in many industrial processes such as the production of vinegar, vitamin C, the antidiabetic drug miglitol, and various artificial...
Acetic acid bacteria are used in many industrial processes such as the production of vinegar, vitamin C, the antidiabetic drug miglitol, and various artificial flavorings. These industrially important reactions are primarily carried out by an arsenal of periplasmic-facing membrane-bound dehydrogenases that incompletely oxidize their substrates and shuttle electrons directly into the respiratory chain. Among these dehydrogenases, GOX in was predicted to be a pyrroloquinoline quinone-dependent dehydrogenase of unknown function. However, after multiple analysis by a number of labs, no dehydrogenase activity has been detected. Reanalysis of GOX1969 sequence and structure reveals similarities to BamB, which functions as a subunit of the β-barrel assembly machinery complex that is responsible for the assembly of β-barrel outer membrane proteins in Gram-negative bacteria. To test if the physiological function of GOX1969 is similar to BamB in , we introduced the gene into an ∆ mutant. Growth deficiencies in the ∆ mutant were restored when was expressed on the plasmid pGox1969. Furthermore, increased membrane permeability conferred by deletion was restored upon expression, which suggests a direct link between GOX1969 and a role in maintaining outer membrane stability. Together, this evidence strongly suggests that GOX1969 is functionally acting as a BamB in . As such, functional information on uncharacterized genes will provide new insights that will allow for more accurate modeling of acetic acid bacterial metabolism and further efforts to design rational strains for industrial use.IMPORTANCE is an industrially important member of the acetic acid bacteria. Experimental characterization of putative genes is necessary to identify targets for further engineering of rational acetic acid bacteria strains that can be used in the production of vitamin C, antidiabetic compounds, artificial flavorings, or novel compounds. In this study, we have identified an undefined dehydrogenase GOX1969 with no known substrate and defined structural similarities to outer membrane biogenesis protein BamB in K12. Furthermore, we demonstrate that GOX1969 is capable of complementing knockout phenotypes in K12. Taken together, these findings enhance our understanding of physiology and expand the list of potential targets for future industrial strain design.
PubMed: 38916353
DOI: 10.1128/spectrum.01060-24 -
BioRxiv : the Preprint Server For... Jun 2024Tripartite resistance nodulation and cell division multidrug efflux pumps span the periplasm and are a major driver of multidrug resistance among Gram-negative bacteria....
Tripartite resistance nodulation and cell division multidrug efflux pumps span the periplasm and are a major driver of multidrug resistance among Gram-negative bacteria. The periplasm provides a distinct environment between the inner and outer membranes of Gram-negative bacteria. Cations, such as Mg , become concentrated within the periplasm and, in contrast to the cytoplasm, its pH is sensitive to conditions outside the cell. Here, we reveal an interplay between Mg and pH in modulating the dynamics of the periplasmic adaptor protein, AcrA, and its function within the prototypical AcrAB-TolC multidrug efflux pump from . In the absence of Mg , AcrA becomes increasingly plastic within acidic conditions, but when Mg is bound this is ameliorated, resulting in domain specific organisation in neutral to weakly acidic regimes. We establish a unique histidine residue directs these structural dynamics and is essential for sustaining pump efflux activity across acidic, neutral, and alkaline conditions. Overall, we propose Mg conserves the structural mobility of AcrA to ensure optimal AcrAB-TolC function within rapid changing environments commonly faced by the periplasm during bacterial infection and colonization. This work highlights that Mg is an important mechanistic component in this pump class and possibly across other periplasmic lipoproteins.
PubMed: 38915626
DOI: 10.1101/2024.06.10.597921 -
ACS Omega Jun 2024Membrane permeability is a natural defense barrier that contributes to increased bacterial drug resistance, particularly for Gram-negative pathogens. As such, accurate...
Membrane permeability is a natural defense barrier that contributes to increased bacterial drug resistance, particularly for Gram-negative pathogens. As such, accurate delivery of the antibacterial agent to the target has become a growing research area in the infectious diseases field as a means of improving drug efficacy. Although the efficient transport of siderophore-antibiotic conjugates into the cytosol still remains challenging, great success has been achieved in the delivery of β-lactam antibiotics into the periplasmic space via bacterial iron uptake pathways. Cefiderocol, the first siderophore-cephalosporin conjugate approved by the US Food and Drug Administration, is a good example. These conjugation strategies have also been applied to the precise delivery of β-lactamase inhibitors, such as penicillin-based sulfone , to restore β-lactam antibiotic efficacy in multidrug-resistant bacteria. Herein, we have explored the impact on the bacterial activity of by modifying its iron chelator moiety. A set of derivatives functionalized with diverse iron chelator groups and linkages to the scaffold (compounds -) were synthesized and assayed in vitro. The results on the ability of derivatives - to recover β-lactam antibiotic efficacy in difficult-to-treat pathogens that produce various β-lactamase enzymes, along with kinetic studies with the isolated enzymes, allowed us to identify compound , a novel β-lactamase inhibitor with an expanded spectrum of activity. Molecular dynamics simulation studies provided us with further information regarding the molecular basis of the relative inhibitory properties of the most relevant compound described herein.
PubMed: 38911797
DOI: 10.1021/acsomega.4c02984 -
PloS One 2024Antibiotic resistance genes (ARGs) transfer rapidly among bacterial species all over the world contributing to the aggravation of antibiotic resistance crisis....
BACKGROUND
Antibiotic resistance genes (ARGs) transfer rapidly among bacterial species all over the world contributing to the aggravation of antibiotic resistance crisis. Antibiotics at sub-inhibitory concentration induce horizontal gene transfer (HRT) between bacteria, especially through conjugation. The role of common non-antibiotic pharmaceuticals in the market in disseminating antibiotic resistance is not well studied.
OBJECTIVES
In this work, we indicated the effect of some commonly used non-antibiotic pharmaceuticals including antiemetic (metoclopramide HCl) and antispasmodics (hyoscine butyl bromide and tiemonium methyl sulfate) on the plasmid-mediated conjugal transfer of antibiotic resistance genes between pathogenic E. coli in the gastric intestinal tract (GIT).
METHODS
Broth microdilution assay was used to test the antibacterial activity of the tested non-antibiotic pharmaceuticals. A conjugation mating system was applied in presence of the studied non-antibiotic pharmaceuticals to test their effect on conjugal transfer frequency. Plasmid extraction and PCR were performed to confirm the conjugation process. Transmission electron microscopy (TEM) was used for imaging the effect of non-antibiotic pharmaceuticals on bacterial cells.
RESULTS
No antibacterial activity was reported for the used non-antibiotic pharmaceuticals. Plasmid-mediated conjugal transfer between isolates was induced by metoclopramide HCl but suppressed by hyoscine butyl bromide. Tiemonium methylsulfate slightly promoted conjugal transfer. Aggregation between cells and periplasmic bridges was clear in the case of metoclopramide HCl while in presence of hyoscine butyl bromide little affinity was observed.
CONCLUSION
This study indicates the contribution of non-antibiotic pharmaceuticals to the dissemination and evolution of antibiotic resistance at the community level. Metoclopramide HCl showed an important role in the spread of antibiotic resistance.
Topics: Escherichia coli; Gene Transfer, Horizontal; Plasmids; Metoclopramide; Microbial Sensitivity Tests; Anti-Bacterial Agents; Drug Resistance, Bacterial; Conjugation, Genetic; Drug Resistance, Microbial
PubMed: 38905247
DOI: 10.1371/journal.pone.0304980 -
Applied and Environmental Microbiology Jun 2024Purple sulfur bacteria (PSB) are capable of anoxygenic photosynthesis via oxidizing reduced sulfur compounds and are considered key drivers of the sulfur cycle in a...
UNLABELLED
Purple sulfur bacteria (PSB) are capable of anoxygenic photosynthesis via oxidizing reduced sulfur compounds and are considered key drivers of the sulfur cycle in a range of anoxic environments. In this study, we show that (a PSB species) is capable of autotrophic growth using pyrite as the electron and sulfur source. Comparative growth profile, substrate characterization, and transcriptomic sequencing data provided valuable insight into the molecular mechanisms underlying the bacterial utilization of pyrite and autotrophic growth. Specifically, the pyrite-supported cell cultures ("py"') demonstrated robust but much slower growth rates and distinct patterns from their sodium sulfide-amended positive controls. Up to ~200-fold upregulation of genes encoding various - and -type cytochromes was observed in "py," pointing to the high relevance of these molecules in scavenging and relaying electrons from pyrite to cytoplasmic metabolisms. Conversely, extensive downregulation of genes related to LH and RC complex components indicates that the electron source may have direct control over the bacterial cells' photosynthetic activity. In terms of sulfur metabolism, genes encoding periplasmic or membrane-bound proteins (e.g., FccAB and SoxYZ) were largely upregulated, whereas those encoding cytoplasmic proteins (e.g., Dsr and Apr groups) are extensively suppressed. Other notable differentially expressed genes are related to flagella/fimbriae/pilin(+), metal efflux(+), ferrienterochelin(-), and [NiFe] hydrogenases(+). Characterization of the biologically reacted pyrite indicates the presence of polymeric sulfur. These results have, for the first time, put the interplay of PSB and transition metal sulfide chemistry under the spotlight, with the potential to advance multiple fields, including metal and sulfur biogeochemistry, bacterial extracellular electron transfer, and artificial photosynthesis.
IMPORTANCE
Microbial utilization of solid-phase substrates constitutes a critical area of focus in environmental microbiology, offering valuable insights into microbial metabolic processes and adaptability. Recent advancements in this field have profoundly deepened our knowledge of microbial physiology pertinent to these scenarios and spurred innovations in biosynthesis and energy production. Furthermore, research into interactions between microbes and solid-phase substrates has directly linked microbial activities to the surrounding mineralogical environments, thereby enhancing our understanding of the relevant biogeochemical cycles. Our study represents a significant step forward in this field by demonstrating, for the first time, the autotrophic growth of purple sulfur bacteria using insoluble pyrite (FeS2) as both the electron and sulfur source. The presented comparative growth profiles, substrate characterizations, and transcriptomic sequencing data shed light on the relationships between electron donor types, photosynthetic reaction center activities, and potential extracellular electron transfer in these organisms capable of anoxygenic photosynthesis. Furthermore, the findings of our study may provide new insights into early-Earth biogeochemical evolutions, offering valuable constraints for understanding the environmental conditions and microbial processes that shaped our planet's history.
PubMed: 38899885
DOI: 10.1128/aem.00863-24 -
PLoS Computational Biology Jun 2024Periplasmic binding proteins (PBPs) are bacterial proteins commonly used as scaffolds for substrate-detecting biosensors. In these biosensors, effector proteins (for...
Periplasmic binding proteins (PBPs) are bacterial proteins commonly used as scaffolds for substrate-detecting biosensors. In these biosensors, effector proteins (for example fluorescent proteins) are inserted into a PBP such that the effector protein's output changes upon PBP-substate binding. The insertion site is often determined by comparison of PBP apo/holo crystal structures, but random insertion libraries have shown that this can miss the best sites. Here, we present a PBP biosensor design method based on residue contact analysis from molecular dynamics. This computational method identifies the best previously known insertion sites in the maltose binding PBP, and suggests further previously unknown sites. We experimentally characterise fluorescent protein insertions at these new sites, finding they too give functional biosensors. Furthermore, our method is sufficiently flexible to both suggest insertion sites compatible with a variety of effector proteins, and be applied to binding proteins beyond PBPs.
PubMed: 38885277
DOI: 10.1371/journal.pcbi.1012212 -
Biochemistry. Biokhimiia May 2024Technology of production of single-domain antibodies (NANOBODY® molecules, also referred to as nanoantibodies, nAb, or molecules based on other stable protein...
Technology of production of single-domain antibodies (NANOBODY® molecules, also referred to as nanoantibodies, nAb, or molecules based on other stable protein structures) and their derivatives to solve current problems in biomedicine is becoming increasingly popular. Indeed, the format of one small, highly soluble protein with a stable structure, fully functional in terms of specific recognition, is very convenient as a module for creating multivalent, bi-/oligo-specific genetically engineered targeting molecules and structures. Production of nAb in periplasm of E. coli bacterium is a very convenient and fairly universal way to obtain analytical quantities of nAb for the initial study of the properties of these molecules and selection of the most promising nAb variants. The situation is more complicated with production of bi- and multivalent derivatives of the initially selected nAbs under the same conditions. In this work, extended linker sequences (52 and 86 aa) between the antigen-recognition modules in the cloned expression constructs were developed and applied in order to increase efficiency of production of bispecific nanoantibodies (bsNB) in the periplasm of E. coli bacteria. Three variants of model bsNBs described in this study were produced in the periplasm of bacteria and isolated in soluble form with preservation of functionality of all the protein domains. If earlier our attempts to produce bsNB in the periplasm with traditional linkers no longer than 30 aa were unsuccessful, the extended linkers used here provided a significantly more efficient production of bsNB, comparable in efficiency to the traditional production of original monomeric nAbs. The use of sufficiently long linkers could presumably be useful for increasing efficiency of production of other bsNBs and similar molecules in the periplasm of E. coli bacteria.
Topics: Escherichia coli; Periplasm; Antibodies, Bispecific; Single-Domain Antibodies; Antigens
PubMed: 38880653
DOI: 10.1134/S0006297924050134 -
Journal of Molecular Biology Jun 2024TolC is the outer membrane protein responsible for antibiotic efflux in E. coli. Compared to other outer membrane proteins it has an unusual fold and has been shown to...
TolC is the outer membrane protein responsible for antibiotic efflux in E. coli. Compared to other outer membrane proteins it has an unusual fold and has been shown to fold independently of commonly used periplasmic chaperones, SurA and Skp. Here we find that the assembly of TolC involves the formation of two folded intermediates using circular dichroism, gel electrophoresis, site-specific disulfide bond formation and radioactive labeling. First the TolC monomer folds, and then TolC assembles into a trimer both in detergent-free buffer and in the presence of detergent micelles. We find that a TolC trimer also forms in the periplasm and is present in the periplasm before it inserts in the outer membrane. The monomeric and trimeric folding intermediates may be used in the future to develop a new approach to antibiotic efflux pump inhibition by targeting the assembly pathway of TolC.
PubMed: 38871177
DOI: 10.1016/j.jmb.2024.168652 -
Microbiology Spectrum Jun 2024CSV86 displays the unique property of preferential utilization of aromatic compounds over simple carbon sources like glucose and glycerol and their co-metabolism with...
CSV86 displays the unique property of preferential utilization of aromatic compounds over simple carbon sources like glucose and glycerol and their co-metabolism with organic acids. Well-characterized growth conditions, aromatic compound metabolic pathways and their regulation, genome sequence, and advantageous eco-physiological traits (indole acetic acid production, alginate production, fusaric acid resistance, organic sulfur utilization, and siderophore production) make it an ideal host for metabolic engineering. Strain CSV86 was engineered for Carbaryl (1-naphthyl--methylcarbamate) degradation via salicylate-catechol route by expression of a Carbaryl hydrolase (CH) and a 1-naphthol 2-hydroxylase (1NH). Additionally, the engineered strain exhibited faster growth on Carbaryl upon expression of the McbT protein (encoded by the T gene, a part of Carbaryl degradation upper operon of sp. C5pp). Bioinformatic analyses predict McbT to be an outer membrane protein, and Carbaryl-dependent expression suggests its probable role in Carbaryl uptake. Enzyme activity and protein analyses suggested periplasmic localization of CH (carrying transmembrane domain plus signal peptide sequence at the N-terminus) and 1NH, enabling compartmentalization of the pathway. Enzyme activity, whole-cell oxygen uptake, spent media analyses, and qPCR results suggest that the engineered strain preferentially utilizes Carbaryl over glucose. The plasmid-encoded degradation property was stable for 75-90 generations even in the absence of selection pressure (kanamycin or Carbaryl). These results indicate the utility of CSV86 as a potential host for engineering various aromatic compound degradation pathways.IMPORTANCEThe current study describes engineering of Carbaryl metabolic pathway in CSV86. Carbaryl, a naphthalene-derived carbamate pesticide, is known to act as an endocrine disruptor, mutagen, cytotoxin, and carcinogen. Removal of xenobiotics from the environment using bioremediation faces challenges, such as slow degradation rates, instability of the degradation phenotype, and presence of simple carbon sources in the environment. The engineered CSV86-MEC2 overcomes these disadvantages as Carbaryl was degraded preferentially over glucose. Furthermore, the plasmid-borne degradation phenotype is stable, and presence of glucose and organic acids does not repress Carbaryl metabolism in the strain. The study suggests the role of outer membrane protein McbT in Carbaryl transport. This work highlights the suitability of CSV86 as an ideal host for engineering aromatic pollutant degradation pathways.
PubMed: 38869268
DOI: 10.1128/spectrum.00284-24