Biology subjects

Morcinek-Orlowska, J.

Publications and source records attributed to Morcinek-Orlowska, J..

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↗

bioRxiv2023

Bam complex associated proteins in Escherichia coli are functionally linked to peptidoglycan biosynthesis, membrane fluidity and DNA replication

Biogenesis of the bacterial outer membrane is key to bacterial survival and antibiotic resistance. Central to this is the {beta}-barrel assembly machine (Bam) complex and its associated chaperones, which are responsible for transport, folding and insertion of outer membrane proteins (OMPs). The Escherichia coli Bam complex is composed of two essential subunits, BamA and BamD, and three non-essential accessory lipoproteins, BamB, BamC and BamE. Optimal Bam function is further dependent on the non-essential periplasmic chaperones DegP, Skp and SurA. Despite intensive study, the specific function of these non-essential Bam-associated proteins is not fully understood. Here, we analysed {Delta}bamB, {Delta}bamC, {Delta}bamE, {Delta}surA, {Delta}skp and {Delta}degP knockout strains by phenotypic screening, conservation analysis and high-throughput genetics. We identify hundreds of synthetic-lethal interactions and reveal that Bam complex activity is impacted by changes in outer membrane lipid composition and that enterobacterial common antigen is essential in the absence of the chaperone SurA. We also show genes responsible for synthesis of peptidoglycan are synthetically-lethal with Bam accessory lipoprotein encoding genes. Together, our data indicates potential mechanisms for coordination of OMP biogenesis with other cellular growth processes such as LPS and peptidoglycan biogenesis.

microbiology↗

bioRxiv2020

Global query on bacterial sirtuin CobB interactants reveals crosstalk with PRPP synthase Prs

In bacteria, post-translational acetylation of lysine residues affects the activities of numerous proteins, thus constituting an important regulatory mechanism that influences bacterial growth and adaptation to various environments. Conversely, the modification level of some lysine residues is controlled by deacetylases that remove the acetyl group. Most bacterial deacetylases are homologous to eukaryotic sirtuins, which utilize NAD+ as a cofactor. The Escherichia coli genome encodes a single sirtuin - CobB. However, both the regulation of CobB activity and the role that reversible acetylation plays in the control of protein functions and cellular pathways are not fully understood. In this study, we demonstrate that CobB forms a stable complex with PRPP synthase Prs. PRPP synthase is responsible for providing precursor metabolite for the synthesis of certain amino acids as well as nucleotides, including the cofactor NAD+. This association stimulates the deacetylation rate by CobB and protects it from inhibition by its reaction byproduct nicotinamide. We present evidence indicating that acetylation of Prs is physiologically significant and impacts E. coli metabolism and global protein acetylation level, although it does not affect CobB binding in vitro. In turn, Prs can be deacetylated by CobB, while formation of CobB-Prs complex formation safeguards PRPP synthase activity under non-optimal conditions. We propose that formation of the complex regulates deacetylation of other protein substrates by CobB.

molecular biology↗