Biology subjects

Tesseur, C.

Publications and source records attributed to Tesseur, C..

3 recordsLinked to original sources

bioRxiv2026

A polarity-controlled Tad nanomachine enables prey invasion in a bacterial predator

Type IV pili are dynamic surface appendages assembled by envelope-spanning nanomachines that mediate diverse bacterial interactions, yet how these systems are adapted to predatory lifestyles remains poorly understood. Here we investigate the tight adherence (Tad) machinery of the obligate predator Bdellovibrio bacteriovorus. Using inducible CRISPR interference combined with live-cell and microfluidics imaging, we show that the Tad system is essential for prolonged prey attachment and subsequent prey remodeling and invasion. The machinery assembles specifically at the invasive cell pole before prey encounter and is temporally coordinated with the predatory cell cycle. We further demonstrate that polar localization of the Tad machinery depends on the polarity hub RomR. In addition, the atypical TadZA fusion ATPase interacts with RomR, identifying a potential molecular link between polarity control and Tad assembly. Together, our findings reveal how spatiotemporal control of a conserved filament system supports bacterial predation.

microbiology↗

bioRxiv2025

Chromosome segregation dynamics during the cell cycle of Staphylococcus aureus

Research on chromosome organization and cell cycle progression in spherical bacteria, particularly Staphylococcus aureus, remains limited and fragmented. In this study, we established a working model to investigate chromosome dynamics in S. aureus using a Fluorescent Repressor-Operator System (FROS), which enabled precise localization of specific chromosomal loci. This approach revealed that the S. aureus cell cycle and chromosome replication cycle are not coupled, with cells exhibiting two segregated origins of replication at the start of the cell cycle. The chromosome has a specific origin-terminus-origin conformation, with origins localizing near the membrane, towards the tip of each hemisphere, or the "cell poles". We further used this system to assess the role of various proteins with a role in S. aureus chromosome biology, focusing on the ParB-parS and SMC-ScpAB systems. Our results demonstrate that ParB binds five parS chromosomal sequences and the resulting complexes influence chromosome conformation, but play a minor role in chromosome compaction and segregation. In contrast, the SMC-ScpAB complex plays a key role in S. aureus chromosome biology, contributing to chromosome compaction, segregation and spatial organization. Additionally, we systematically assessed and compared the impact of proteins linking chromosome segregation to cell division--Noc, FtsK, SpoIIIE and XerC--on origin and terminus number and positioning. This work provides a comprehensive study of the factors governing chromosome dynamics and organization in S. aureus, contributing to our knowledge on chromosome biology of spherical bacteria.

microbiology↗

bioRxiv2023

Distinct dynamics and proximity networks of hub proteins at the prey-invading cell pole in a predatory bacterium

In bacteria, cell poles function as subcellular compartments where proteins localize during specific lifecycle stages, orchestrated by polar "hub" proteins. Whereas most described bacteria inherit an "old" pole from the mother cell and a "new" pole from cell division, polarizing cells at birth, non-binary division poses challenges for establishing cell polarity, particularly for daughter cells inheriting only new poles. We investigated polarity dynamics in the obligate predatory bacterium Bdellovibrio bacteriovorus, proliferating through filamentous growth followed by non-binary division within prey bacteria. Monitoring the subcellular localization of two proteins known as polar hubs in other species, RomR and DivIVA, revealed RomR as an early polarity marker in B. bacteriovorus. RomR already marks the future anterior poles of the progeny during the predators growth phase, in a define time window closely following the onset of divisome assembly and the end of chromosome segregation. In contrast to RomRs stable unipolar localization in the progeny, DivIVA exhibits a dynamic pole-to-pole localization. This behaviour changes shortly before division of the elongated predator cell, where DivIVA accumulates at all septa and both poles. In vivo protein interaction networks for DivIVA and RomR, mapped through endogenous miniTurbo-based proximity labeling, further underscore their distinct roles in cell polarization and the importance of the anterior "invasive" cell pole in prey-predator interactions. Our work emphasizes the strict spatiotemporal coordination of cellular processes underlying B. bacteriovorus proliferation, offering insights into the subcellular organization of bacteria with filamentous growth and non-binary division.

microbiology↗