The novel MFS efflux pump SxtP, regulated by the LysR-type transcriptional activator SxtR, is involved in the susceptibility to sulfamethoxazole/trimethoprim (SXT) and the pathogenesis of .

is a notorious opportunistic pathogen responsible for healthcare-associated infections worldwide. Efflux pumps play crucial roles in mediating antimicrobial resistance, motility, and virulence. In this study, we present the identification and characterization of the new efflux pump SxtP belonging to the MFS superfamily (ajor acilitator uperfamily), along with its associated activator ysRtype ranscriptional egulator (LTTR) SxtR, demonstrating their roles in sulfamethoxazole/trimethoprim (also known as co-trimoxazole or SXT) resistance, surface-associated motility and virulence.

Systematic In Silico Assessment of Antimicrobial Resistance Dissemination across the Global Plasmidome.

The emergence of pathogenic strains resistant to multiple antimicrobials is a pressing problem in modern healthcare. Antimicrobial resistance is mediated primarily by dissemination of resistance determinants via horizontal gene transfer. The dissemination of some resistance genes has been well documented, but few studies have analyzed the patterns underpinning the dissemination of antimicrobial resistance genes.

Non-canonical LexA proteins regulate the SOS response in the Bacteroidetes.

Lesions to DNA compromise chromosome integrity, posing a direct threat to cell survival. The bacterial SOS response is a widespread transcriptional regulatory mechanism to address DNA damage. This response is coordinated by the LexA transcriptional repressor, which controls genes involved in DNA repair, mutagenesis and cell-cycle control.

Importance of twitching and surface-associated motility in the virulence of .

is a pathogen of increasing clinical importance worldwide, especially given its ability to readily acquire resistance determinants. Motile strains of this bacterium can move by either or both of two types of motility: (i) twitching, driven by type IV pili, and (ii) surface-associated motility, an appendage-independent form of movement. strain MAR002 possesses both twitching and surface-associated motility.

Flexible comparative genomics of prokaryotic transcriptional regulatory networks.

Background: Comparative genomics methods enable the reconstruction of bacterial regulatory networks using available experimental data. In spite of their potential for accelerating research into the composition and evolution of bacterial regulons, few comparative genomics suites have been developed for the automated analysis of these regulatory systems. Available solutions typically rely on precomputed databases for operon and ortholog predictions, limiting the scope of analyses to processed complete genomes, and several key issues such as the transfer of experimental information or the integration of regulatory information in a probabilistic setting remain largely unaddressed.

Exploration into the origins and mobilization of di-hydrofolate reductase genes and the emergence of clinical resistance to trimethoprim.

Trimethoprim is a synthetic antibacterial agent that targets folate biosynthesis by competitively binding to the di-hydrofolate reductase enzyme (DHFR). Trimethoprim is often administered synergistically with sulfonamide, another chemotherapeutic agent targeting the di-hydropteroate synthase (DHPS) enzyme in the same pathway. Clinical resistance to both drugs is widespread and mediated by enzyme variants capable of performing their biological function without binding to these drugs.

The Interaction of RecA With Both CheA and CheW Is Required for Chemotaxis.

is the most frequently reported cause of foodborne illness. As in other microorganisms, chemotaxis affords key physiological benefits, including enhanced access to growth substrates, but also plays an important role in infection and disease. Chemoreceptor signaling core complexes, consisting of CheA, CheW and methyl-accepting chemotaxis proteins (MCPs), modulate the switching of bacterial flagella rotation that drives cell motility.

Direct interaction between RecA and a CheW-like protein is required for surface-associated motility, chemotaxis and the full virulence of strain ATCC 17978.

is a nosocomial pathogen that causes multi-drug resistant infections mainly in immunocompromised patients. Although this gram-negative species lacks flagella, it is able to move over wet surfaces through a not well characterized type of movement known as surface-associated motility. In this study we demonstrate through the inactivation of the gene (coding a CheW-like protein) and (coding a DNA damage repair and recombination protein) that both genes are involved in the surface-associated motility and chemotaxis of ATCC 17978 strain.

Twitching and Swimming Motility Play a Role in Ralstonia solanacearum Pathogenicity.

is a bacterial plant pathogen causing important economic losses worldwide. In addition to the polar flagella responsible for swimming motility, this pathogen produces type IV pili (TFP) that govern twitching motility, a flagellum-independent movement on solid surfaces. The implication of chemotaxis in plant colonization, through the control flagellar rotation by the proteins CheW and CheA, has been previously reported in In this work, we have identified in this bacterium homologues of the and genes, suggested to play roles in TFP-associated motility analogous to those played by the and genes, respectively.

Origin of the Mobile Di-Hydro-Pteroate Synthase Gene Determining Sulfonamide Resistance in Clinical Isolates.

Sulfonamides are synthetic chemotherapeutic agents that work as competitive inhibitors of the di-hydro-pteroate synthase (DHPS) enzyme, encoded by the gene. Resistance to sulfonamides is widespread in the clinical setting and predominantly mediated by plasmid- and integron-borne genes encoding mutant DHPS enzymes that do not bind sulfonamides. In spite of their clinical importance, the genetic origin of genes remains unknown.

Roles of Efflux Pumps from Different Superfamilies in the Surface-Associated Motility and Virulence of ATCC 17978.

Although the relationship between efflux pumps and antimicrobial resistance is well documented, less is known about the involvement of these proteins in the pathogenicity of this nosocomial pathogen. In previous work, we identified the AbaQ major facilitator superfamily (MFS) efflux pump and demonstrated its participation in the motility and virulence of In the present study, we examined the role in these processes of transporters belonging to different superfamilies of efflux pumps. Genes encoding known or putative permeases belonging to efflux pump superfamilies other than the MFS were selected, and the corresponding knockouts were constructed.

Functional Characterization of AbaQ, a Novel Efflux Pump Mediating Quinolone Resistance in Acinetobacter baumannii.

has emerged as an important multidrug-resistant nosocomial pathogen. In previous work, we identified a putative MFS transporter, AU097_RS17040, involved in the pathogenicity of (M. Pérez-Varela, J.

The Transient Multidrug Resistance Phenotype of Swarming Cells Is Abolished by Sub-inhibitory Concentrations of Antimicrobial Compounds.

Swarming motility is the rapid and coordinated multicellular migration of bacteria across a moist surface. During swarming, bacterial cells exhibit increased resistance to multiple antibiotics, a phenomenon described as adaptive or transient resistance. In this study, we demonstrate that sub-inhibitory concentrations of cefotaxime, ciprofloxacin, trimethoprim, or chloramphenicol, but not that of amikacin, colistin, kanamycin or tetracycline, impair swarming.

Comparative genomics of the DNA damage-inducible network in the Patescibacteria.

Metagenomics provide unprecedented insights into the genetic diversity of uncultivated bacteria inhabiting natural environments. Recent surveys have uncovered a major radiation of candidate phyla encompassing the Patescibacteria superphylum. Patescibacteria have small genomes and a presumed symbiotic or parasitic lifestyle, but the difficulty in culturing representative members constrains the characterization of behavioural and adaptive traits.

Mutations in the β-Subunit of the RNA Polymerase Impair the Surface-Associated Motility and Virulence of Acinetobacter baumannii.

is a major cause of antibiotic-resistant nosocomial infections worldwide. In this study, several rifampin-resistant spontaneous mutants obtained from the ATCC 17978 strain that differed in their point mutations in the gene, encoding the β-subunit of the RNA polymerase, were isolated. All the mutants harboring amino acid substitutions in position 522 or 540 of the RpoB protein were impaired in surface-associated motility and had attenuated virulence in the fertility model of The transcriptional profile of these mutants included six downregulated genes encoding proteins homologous to transporters and metabolic enzymes widespread among clinical isolates.

Molecular Interaction and Cellular Location of RecA and CheW Proteins in during SOS Response and Their Implication in Swarming.

In addition to its role in DNA damage repair and recombination, the RecA protein, through its interaction with CheW, is involved in swarming motility, a form of flagella-dependent movement across surfaces. In order to better understand how SOS response modulates swarming, in this work the location of RecA and CheW proteins within the swarming cells has been studied by using super-resolution microscopy. Further, and after docking studies, the specific RecA and CheW regions associated with the RecA-CheW interaction have also been confirmed by site-directed mutagenesis and immunoprecipitation techniques.

The Verrucomicrobia LexA-Binding Motif: Insights into the Evolutionary Dynamics of the SOS Response.

The SOS response is the primary bacterial mechanism to address DNA damage, coordinating multiple cellular processes that include DNA repair, cell division, and translesion synthesis. In contrast to other regulatory systems, the composition of the SOS genetic network and the binding motif of its transcriptional repressor, LexA, have been shown to vary greatly across bacterial clades, making it an ideal system to study the co-evolution of transcription factors and their regulons. Leveraging comparative genomics approaches and prior knowledge on the core SOS regulon, here we define the binding motif of the Verrucomicrobia, a recently described phylum of emerging interest due to its association with eukaryotic hosts.

SOS System Induction Inhibits the Assembly of Chemoreceptor Signaling Clusters in Salmonella enterica.

Swarming, a flagellar-driven multicellular form of motility, is associated with bacterial virulence and increased antibiotic resistance. In this work we demonstrate that activation of the SOS response reversibly inhibits swarming motility by preventing the assembly of chemoreceptor-signaling polar arrays. We also show that an increase in the concentration of the RecA protein, generated by SOS system activation, rather than another function of this genetic network impairs chemoreceptor polar cluster formation.

Novobiocin Inhibits the Antimicrobial Resistance Acquired through DNA Damage-Induced Mutagenesis in Acinetobacter baumannii.

Acinetobacter baumannii, a worldwide emerging nosocomial pathogen, acquires antimicrobial resistances in response to DNA-damaging agents, which increase the expression of multiple error-prone DNA polymerase components. Here we show that the aminocoumarin novobiocin, which inhibits the DNA damage response in Gram-positive bacteria, also inhibits the expression of error-prone DNA polymerases in this Gram-negative multidrug-resistant pathogen and, consequently, its potential acquisition of antimicrobial resistance through DNA damage-induced mutagenesis.

Significance of tagI and mfd genes in the virulence of non-typeable Haemophilus influenzae.

Non-typeable Haemophilus influenzae (NTHi) is an opportunist pathogen well adapted to the human upper respiratory tract and responsible for many respiratory diseases. In the human airway, NTHi is exposed to pollutants, such as alkylating agents, that damage its DNA. In this study, we examined the significance of genes involved in the repair of DNA alkylation damage in NTHi virulence.

An SOS Regulon under Control of a Noncanonical LexA-Binding Motif in the Betaproteobacteria.

Unlabelled: The SOS response is a transcriptional regulatory network governed by the LexA repressor that activates in response to DNA damage. In the Betaproteobacteria, LexA is known to target a palindromic sequence with the consensus sequence CTGT-N8-ACAG. We report the characterization of a LexA regulon in the iron-oxidizing betaproteobacterium Sideroxydans lithotrophicus.

Differential roles of antimicrobials in the acquisition of drug resistance through activation of the SOS response in Acinetobacter baumannii.

The effect of antimicrobials on SOS-mediated mutagenesis induction depends on the bacterial species and the antimicrobial group. In this work, we studied the effect of different families of antimicrobial agents used in clinical therapy against Acinetobacter baumannii in the induction of mutagenesis in this multiresistant Gram-negative pathogen. The data showed that ciprofloxacin and tetracycline induce SOS-mediated mutagenesis, whereas colistin and meropenem, which are extensively used in clinical therapy, do not.

RecA protein plays a role in the chemotactic response and chemoreceptor clustering of Salmonella enterica.

The RecA protein is the main bacterial recombinase and the activator of the SOS system. In Escherichia coli and Salmonella enterica sv. Typhimurium, RecA is also essential for swarming, a flagellar-driven surface translocation mechanism widespread among bacteria.

Role of Acinetobacter baumannii UmuD homologs in antibiotic resistance acquired through DNA damage-induced mutagenesis.

The role of Acinetobacter baumannii ATCC 17978 UmuDC homologs A1S_0636-A1S_0637, A1S_1174-A1S_1173, and A1S_1389 (UmuDAb) in antibiotic resistance acquired through UV-induced mutagenesis was evaluated. Neither the growth rate nor the UV-related survival of any of the three mutants was significantly different from that of the wild-type parental strain. However, all mutants, and especially the umuDAb mutant, were less able to acquire resistance to rifampin and streptomycin through the activities of their error-prone DNA polymerases.