Biology subjects

Van Overfelt, S. S. F.

Publications and source records attributed to Van Overfelt, S. S. F..

3 recordsLinked to original sources

bioRxiv2026

A growth-inhibitory dUTPase from Mosigvirus AV110 disrupts cell division and host physiology in Escherichia coli

dUTPases are essential enzymes for nucleotide metabolism as they catalyze the hydrolysis of dUTP to dUMP, thus preventing the toxic incorporation of uracil into DNA. dUTPases are found in all domains of life, including bacteriophages, where they serve multiple functions to support phage propagation. Phage-encoded dUTPases reduce cellular dUTP levels and provide precursors for de novo dTTP synthesis and the synthesis of modified nucleotides, which are important to avoid DNA-based phage defense systems. In this study, we focused on the dimeric dUTPase Gp135, encoded by the Mosigvirus phage AV110, and examined its effect on growth, cell morphology, DNA replication and cell division of AV110s host, extended-spectrum beta-lactamase-producing E. coli. We observed that Gp135 significantly inhibited growth by disrupting DNA replication and cell division. This resulted in cytoplasmic voids, cell elongation, and ultimately cell death. We further demonstrated the diversity of phage-encoded dUTP/dCTPases through phylogenetic analysis, identifying four distinct clusters: one comprising the most common dUTPases, which form trimers; two more divergent clusters comprising dimeric dUTP/dCTPases; and one new cluster of more diverse, uncharacterized dUTPases and dNTPases. Overall, our results highlight the evolutionary and functional diversity of phage-encoded dUTP/dCTPases, with the Mosigvirus AV110 dUTP/dCTPase illustrating their role in supporting phage propagation.

microbiology↗

bioRxiv2026

A phage-encoded host transcription modulator, Htm, reprograms the transcriptome of ESBL Escherichia coli

During phage infection, phages reprogram their host to secure energy, building blocks for their genome, and proteins, as well as the transcription and translation machinery required to replicate their genome and produce phage particles. This also includes reprogramming the host transcriptome to modify host gene expression and align it with the needs of the phage during infection. In this study, we present a putative early-expressed protein, Gp204 of Mosigvirus AV110, renamed Host transcription modulator (Htm), that has a broad impact on the extended-spectrum beta-lactamase (ESBL)- associated E. coli transcriptome. Overexpression of Htm decreased the growth rate of ESBL-E. coli and caused DNA condensation. Htm is structurally similar to bacterial enhancer-binding proteins, binds ssDNA, and alters the expression levels of over 700 E. coli genes when expressed. The majority of these genes were upregulated and are involved in multiple pathways, such as galactose metabolism and pentose and glucuronate interconversions, which may promote the synthesis of purines, pyrimidines, and histidine, all of which are required for the replication, transcription, and translation of the phage genome. Furthermore, energy production is likely to be upregulated by increased availability of acetyl-CoA, resulting from, among other factors, fatty acid degradation. Htm also downregulated the expression of the structural genes involved in flagellar assembly and multiple two-component systems. In conclusion, Htm could promote phage progeny production by increasing the availability of nucleotides, amino acids, and energy, while inhibiting non-essential processes, such as flagella formation.

microbiology↗

bioRxiv2026

The Mosigvirus AV110 Elongasome-Modulating Peptide (Emp) inhibits Escherichia coli growth by targeting Mre-dependent peptidoglycan synthesis

Extended-spectrum {beta}-lactamase and AmpC-producing Escherichia coli (ESBL/AmpC E. coli) are increasingly recognized as public health threats due to their resistance to commonly used antibiotics. With limited treatment options available, new antibacterials and antibacterial targets can be explored by studying early-expressed phage proteins involved in host reprogramming, as these proteins interact with and disrupt essential bacterial processes. A systematic screening of 45 early-expressed proteins with unknown function of Mosigvirus AV110 identified six proteins that inhibit the growth of ESBL/AmpC E. coli, suggesting a role in host reprogramming. In-depth analysis of Gp94, termed Elongasome-Modulating Peptide (Emp), demonstrated that it alters cell morphology and the localization of peptidoglycan synthesis. This effect could be partially complemented by MreB and MreD. Since Emp interacts directly with MreB, MreC, and MreD, we propose that Emp perturbs elongasome-associated peptidoglycan synthesis, thus providing a scaffold for developing new antibacterials against ESBL/AmpC-producing E. coli.

microbiology↗