Escherichia coli OxyS RNA triggers cephalothin resistance by modulating the expression of CRP-associated genes

Tiny but Mighty: Small RNAs-The Micromanagers of Bacterial Survival, Virulence, and Host-Pathogen Interactions

Bacterial pathogens have evolved diverse strategies to infect hosts, evade immune responses, and establish successful infections. While the role of transcription factors in bacterial virulence is well documented, emerging evidence highlights the significant contribution of small regulatory RNAs (sRNAs) in bacterial pathogenesis. These sRNAs function as posttranscriptional regulators that fine-tune gene expression, enabling bacteria to adapt rapidly to challenging environments. This review explores the multifaceted roles of bacterial sRNAs in host-pathogen interactions. Firstly, it examines how sRNAs regulate pathogenicity by modulating the expression of key virulence factors, including fimbriae, toxins, and secretion systems, followed by discussing the role of sRNAs in bacterial stress response mechanisms that counteract host immune defenses, such as oxidative and envelope stress. Additionally, this review investigates the involvement of sRNAs in antibiotic resistance by regulating efflux pumps, biofilm formation, and membrane modifications, which contribute to multi-drug resistance phenotypes. Lastly, this review highlights how sRNAs contribute to intra- and interspecies communication through quorum sensing, thereby coordinating bacterial behavior in response to environmental cues. Understanding these regulatory networks governed by sRNAs is essential for the development of innovative antimicrobial strategies. This review highlights the growing significance of sRNAs in bacterial pathogenicity and explores their potential as therapeutic targets for the treatment of bacterial infections.

The Role of the Hfq Protein in Bacterial Resistance to Antibiotics: A Narrative Review

The antibiotic resistance of pathogenic microorganisms is currently one of most major medical problems, causing a few million deaths every year worldwide due to untreatable bacterial infections. Unfortunately, the prognosis is even worse, as over 8 million deaths associated with antibiotic resistance are expected to occur in 2050 if no new effective antibacterial treatments are discovered. The Hfq protein has been discovered as a bacterial RNA chaperone. However, subsequent studies have indicated that this small protein (composed of 102 amino acid residues in Escherichia coli) has more activities, including binding to DNA and influencing its compaction, interaction with biological membranes, formation of amyloid-like structures, and others. Although Hfq is known to participate in many cellular processes, perhaps surprisingly, only reports from recent years have demonstrated its role in bacterial antibiotic resistance. The aim of this narrative review is to discuss how can Hfq affects antibiotic resistance in bacteria and propose how this knowledge may facilitate developing new therapeutic strategies against pathogenic bacteria. We indicate that the mechanisms by which the Hfq protein modulates the response of bacterial cells to antibiotics are quite different, from the regulation of the expression of genes coding for proteins directly involved in antibiotic transportation or action, through direct effects on membranes, to controlling the replication or transposition of mobile genetic elements bearing antibiotic resistance genes. Therefore, we suggest that Hfq could be considered a potential target for novel antimicrobial compounds. We also discuss difficulties in developing such drugs, but since Hfq appears to be a promising target for drugs that may enhance the efficacy of antibiotics, we propose that works on such potential therapeutics are encouraged.

Identification and Functional Analysis of ncRNAs Regulating Intrinsic Polymyxin Resistance in Foodborne Proteus vulgaris

Polymyxin, known as the "last line of defense" against bacterial infection, exerts a significant inhibitory effect on a wide range of Gram-negative pathogenic bacteria. The presence of strains, specifically Proteus vulgaris species, displaying intrinsic polymyxin resistance poses significant challenges to current clinical treatment. However, the underlying mechanism responsible for this intrinsic resistance remains unclear. Bacterial non-coding RNAs (ncRNAs) are abundant in genomes and have been demonstrated to have significant regulatory roles in antibiotic resistance across various bacterial species. However, it remains to be determined whether ncRNAs in Proteus vulgaris can regulate intrinsic polymyxin resistance. This study focused on investigating the foodborne Proteus vulgaris strain P3M and its intrinsic polymyxin resistance regulation mediated by ncRNAs. Through a combination of bioinformatics analysis, mutant construction, and phenotypic experimental verification, we successfully identified the ncRNAs involved and their potential target genes. These findings serve as an essential foundation for the precise identification of ncRNAs participating in the intricate regulation process of polymyxin resistance. Additionally, this study offers valuable insights into the efficient screening of bacterial ncRNAs that contribute positively to antibiotic resistance regulation.

Balanced cell division is secured by two different regulatory sites in OxyS RNA

The hydrogen peroxide-induced small RNA OxyS has been proposed to originate from the 3' UTR of a peroxide mRNA. Unexpectedly, phylogenetic OxyS targetome predictions indicate that most OxyS targets belong to the category of "cell cycle," including cell division and cell elongation. Previously, we reported that Escherichia coli OxyS inhibits cell division by repressing expression of the essential transcription termination factor nusG, thereby leading to the expression of the KilR protein, which interferes with the function of the major cell division protein, FtsZ. By interfering with cell division, OxyS brings about cell-cycle arrest, thus allowing DNA damage repair. Cell division and cell elongation are opposing functions to the extent that inhibition of cell division requires a parallel inhibition of cell elongation for the cells to survive. In this study, we report that in addition to cell division, OxyS inhibits mepS, which encodes an essential peptidoglycan endopeptidase that is responsible for cell elongation. Our study indicates that cell-cycle arrest and balancing between cell division and cell elongation are important and conserved functions of the oxidative stress-induced sRNA OxyS.

Sequencing-based methods and resources to study antimicrobial resistance

Antimicrobial resistance extracts high morbidity, mortality and economic costs yearly by rendering bacteria immune to antibiotics. Identifying and understanding antimicrobial resistance are imperative for clinical practice to treat resistant infections and for public health efforts to limit the spread of resistance. Technologies such as next-generation sequencing are expanding our abilities to detect and study antimicrobial resistance. This Review provides a detailed overview of antimicrobial resistance identification and characterization methods, from traditional antimicrobial susceptibility testing to recent deep-learning methods. We focus on sequencing-based resistance discovery and discuss tools and databases used in antimicrobial resistance studies.