Biology subjects

Wegrzyn, G.

Publications and source records attributed to Wegrzyn, G..

3 recordsLinked to original sources

bioRxiv2026

Antibacterial activity of a newly identified phage-derived endolysin and its parental bacteriophage against clinical uropathogenic Escherichia coli

The increasing prevalence of antibiotic-resistant uropathogenic Escherichia coli highlights the need for antibacterial strategies that can complement or extend beyond conventional antibiotic treatment. Bacteriophages and phage-derived lytic enzymes represent promising alternatives because of their distinct mechanisms of bacterial killing and their potential activity against drug-resistant pathogens. In this study, we characterized the newly discovered UPEC-infecting bacteriophage vB-EcoS_57-3 and the endolysin 57_3Lys, encoded by this phage, combining genomic, structural, and functional approaches. The phage demonstrated lytic activity against clinical UPEC isolates and retained antibacterial potential under conditions relevant to the urinary tract. Genomic and sequence analyses revealed distinctive features of 57_3Lys associated with signal-anchor-release endolysins and suggested a less common mode of intracellular translocation and activation. Functional experiments supported the involvement of the bacterial secretion machinery in endolysin-mediated lysis. Notably, the purified enzyme also displayed antibacterial activity against intact clinical E. coli cells, despite the intrinsic barrier presented by the Gram-negative cell envelope. Although this activity developed slowly, it significantly reduced both bacterial culture turbidity and viable cell number. Together, these findings provide new insights into the antimicrobial strategies based on the phages and their phage lytic enzymes, supporting further exploration of vB-EcoS_57-3 and 57_3Lys as potential tools against antibiotic-resistant UPEC.

microbiology↗

bioRxiv2025

Virus-Host Interaction Gets Lousy: P1vir Phage Development Upon Impaired RNA Global Regulation in Escherichia coli Δhfq Mutant Cells

Bacteriophage P1 is a classic tool in molecular genetics, and its virulent derivative, P1vir, is widely used for generalized transduction in Escherichia coli. Phage development depends on host physiology and metabolism, much of which is controlled by RNA-based regulation. The bacterial RNA chaperone Hfq is a global post-transcriptional regulator of stress and metabolic pathways, but its role in phage biology is poorly understood. Here, we examined the effect of Hfq loss on P1vir development by comparing the infection kinetics, virion morphology, and global transcriptomes of P1vir and its E. coli hosts in the wild-type and {Delta}hfq backgrounds. Deletion of hfq impaired P1vir lytic development, yielding smaller plaques, reduced burst size, and virions with smaller heads and thinner tails. P1vir transcriptional profiling showed that {Delta}hfq-specific dysregulation emerged early and intensified over time, with disrupted developmental timing, compromised replication and genome processing, and an unbalanced morphogenetic program. In wild-type cells, P1vir infection triggered broad, time-dependent reprogramming of host gene expression, including the induction of central carbon and amino acid metabolism and other anabolic pathways, consistent with a state that supports productive phage replication. In contrast, the {Delta}hfq mutant mounted a narrower response, with limited metabolic induction and late upregulation of chaperones and proteostasis factors, suggesting the accumulation of misfolded proteins or stalled assembly intermediates. Motif scanning of P1vir transcripts identified candidate Hfq-favored sequence features in several under-induced phage genes, suggesting direct Hfq-RNA regulation. Thus, Hfq, although not essential, is important for efficient P1vir lytic development by coordinating phage gene expression with host reprogramming.

microbiology↗

bioRxiv2021

High diversity in the regulatory region of Stx-converting bacteriophage genomes

Shiga toxin (Stx) is the major virulence factor of enterohemorrhagic Escherichia coli (EHEC), and the stx genes are carried by temperate bacteriophages (Stx phages). The switch between lysogenic and lytic life cycle of the phage, which is crucial for Stx production and for severity of the disease, is regulated by the CI repressor. CI maintain latency by preventing transcription of the replication proteins. Three EHEC phage replication units (Eru1-3) in addition to the classical lambdoid replication region have been described previously, and Stx phages carrying the Eru1 replication region were associated with highly virulent EHEC strains. In this study, we have classified the Eru replication region of 419 Stx phages. In addition to the lambdoid replication region and the three already described Erus, ten novel Erus (named Eru4 to Eru13) were detected. The lambdoid type, Eru1, Eru4 and Eru7 seem to be widely distributed in Western Europe. Notably, EHEC strains involved in severe outbreaks in England and Norway carry Stx phages with Eru1, Eru2, Eru5 and Eru7 replication regions. Phylogenetic analysis of CI repressors from Stx phages revealed eight major clades that largely separate according to Eru type. The classification of replication regions and CI proteins of Stx phages provides an important platform for further studies aimed to assess how characteristics of the replication region influence the regulation of phage life cycle and, consequently, the virulence potential of the host EHEC strain. IMPORTANCEEHEC is an emerging health challenge worldwide and outbreaks caused by this pathogen tend to be more frequent and severe. Increased knowledge on how characteristics of the replication region influence the virulence of E. coli may be used for more precise identification of high-risk EHEC strains.

microbiology↗