Targeting plasmid-encoded proteins that contain immunoglobulin-like domains to combat antimicrobial resistance.

Antimicrobial resistance (AMR) poses a significant threat to human health. Although vaccines have been developed to combat AMR, it has proven challenging to associate specific vaccine antigens with AMR. Bacterial plasmids play a crucial role in the transmission of AMR.

Roles of Proteins Containing Immunoglobulin-Like Domains in the Conjugation of Bacterial Plasmids.

Horizontal transfer of bacterial plasmids generates genetic variability and contributes to the dissemination of the genes that enable bacterial cells to develop antimicrobial resistance (AMR). Several aspects of the conjugative process have long been known, namely, those related to the proteins that participate in the establishment of cell-to-cell contact and to the enzymatic processes associated with the processing of plasmid DNA and its transfer to the recipient cell. In this work, we describe the roles of newly identified proteins that influence the conjugation of several plasmids.

Modulation of AggR levels reveals features of virulence regulation in enteroaggregative E. coli.

Enteroaggregative Escherichia coli (EAEC) strains are one of the diarrheagenic pathotypes. EAEC strains harbor a virulence plasmid (pAA2) that encodes, among other virulence determinants, the aggR gene. The expression of the AggR protein leads to the expression of several virulence determinants in both plasmids and chromosomes.

Gene Duplications in the Genomes of Staphylococci and Enterococci.

Gene duplications are a feature of bacterial genomes. In the present work we analyze the extent of gene duplications in the genomes of three microorganisms that belong to the Firmicutes phylum and that are etiologic agents of several nosocomial infections: , , and . In all three groups, there is an irregular distribution of duplications in the genomes of the strains analyzed.

Expression of a novel class of bacterial Ig-like proteins is required for IncHI plasmid conjugation.

Antimicrobial resistance (AMR) is currently one of the most important challenges to the treatment of bacterial infections. A critical issue to combat AMR is to restrict its spread. In several instances, bacterial plasmids are involved in the global spread of AMR.

Gene duplications in the E. coli genome: common themes among pathotypes.

Background: Gene duplication underlies a significant proportion of gene functional diversity and genome complexity in both eukaryotes and prokaryotes. Although several reports in the literature described the duplication of specific genes in E. coli, a detailed analysis of the extent of gene duplications in this microorganism is needed.

Stringent Response and AggR-Dependent Virulence Regulation in the Enteroaggregative Strain 042.

Virulence expression in the enteroaggregative strain 042 requires the transcriptional activator AggR. We show in this report that, as reported for other virulence factors, the nucleotide second messenger (p)ppGpp is needed for a high expression level of AggR. As expected from these findings, expression of AggR-activated genes such as the AafA pilin subunit is downregulated in the absence of (p)ppGpp.

Mga and H-NS: Two Unrelated Global Regulators with Similar DNA-Binding Properties.

Global regulators play an essential role in the adaptation of bacterial cells to specific niches. Bacterial pathogens thriving in the tissues and organs of their eukaryotic hosts are a well-studied example. Some of the proteins that recognize local DNA structures rather than specific nucleotide sequences act as global modulators in many bacteria, both Gram-negative and -positive.

The incC Sequence Is Required for R27 Plasmid Stability.

IncHI plasmids account for multiple antimicrobial resistance in Salmonella and other enterobacterial genera. These plasmids are generally very stable in their bacterial hosts. R27 is the archetype of IncHI1 plasmids.

Tracking bacterial virulence: global modulators as indicators.

The genomes of Gram-negative bacteria encode paralogues and/or orthologues of global modulators. The nucleoid-associated H-NS and Hha proteins are an example: several enterobacteria such as Escherichia coli or Salmonella harbor H-NS, Hha and their corresponding paralogues, StpA and YdgT proteins, respectively. Remarkably, the genome of the pathogenic enteroaggregative E.

Dielectrophoresis chips improve PCR detection of the food-spoiling yeast Zygosaccharomyces rouxii in apple juice.

Dielectrophoretic (DEP) manipulation of cells present in real samples is challenging. We show in this work that an interdigitated DEP chip can be used to trap and wash a population of the food-spoiling yeast Zygosaccharomyces rouxii that contaminates a sample of apple juice. By previously calibrating the chip, the yeast population loaded is efficiently trapped, washed, and recovered in a small-volume fraction that, in turn, can be used for efficient PCR detection of this yeast.

Success in incorporating horizontally transferred genes: the H-NS protein.

The nucleoid-associated protein H-NS silences unwanted expression of acquired foreign DNA. Ali and colleagues recently identified which horizontally-acquired genes are targeted by H-NS in Salmonella to avoid fitness loss. The reported data strengthen our view about the role of H-NS in bacterial evolution driven by horizontal gene transfer.

HilA-like regulators in Escherichia coli pathotypes: the YgeH protein from the enteroaggregative strain 042.

Background: The HilA protein is the master regulator of the Salmonella pathogenicity island 1 (SPI1). EilA and YgeH proteins show a moderate similarity to HilA and are encoded in pathogenicity islands from several E. coli strains, both pathogenic and non-pathogenic.

Increasing PCR sensitivity by removal of polymerase inhibitors in environmental samples by using dielectrophoresis.

Dielectrophoresis (DEP) is a powerful tool to manipulate cells and molecules in microfluidic chips. However, few practical applications using DEP exist. An immediate practical application of a carbon-electrode DEP system, in removing PCR inhibitors from a sample, is reported in this work.