Biology subjects

Terradot, L.

Publications and source records attributed to Terradot, L..

5 recordsLinked to original sources

bioRxiv2026

Plasmid-encoded host reprogramming promotes plasmid dissemination

Conjugative plasmids are major drivers of antibiotic resistance dissemination, yet how newly transferred plasmids establish in recipient cells remains poorly understood. Here we investigate YfjB, a previously uncharacterized conserved leading-region protein, which is zygotically induced immediately after plasmid entry and acts specifically during the earliest post-transfer stages. Multi-omics analyses reveal that YfjB reprograms host transcription, triggering extensive metabolic rewiring that compensates the transient fitness cost of plasmid acquisition. Structural analyses show that YfjB is a ParB-like protein containing a CTP-binding domain and a helix-turn-helix DNA-binding motif, linked to a previously uncharacterized dimerization module that forms a V-shaped clamp-like architecture compatible with DNA loading. Consistently, live-cell imaging reveals nucleoid-associated foci in transconjugants, and ChIP-seq identifies multiple chromosomal binding sites. We therefore rename the protein HerB (Host Expression Reprogrammer, ParB-like). More broadly, our findings reveal how mobile genetic elements facilitate their dissemination by transiently subverting host physiology.

microbiology↗

bioRxiv2025

Functional and intricate interaction network connecting Helicobacter pylori Cag Type 4 Secretion System surface proteins with outer membrane proteins HopQ and HopZ

The Helicobacter pylori cag pathogenicity island (cagPAI) encodes a complex type IV secretion system (CagT4SS) which is an important virulence factor of H. pylori. Recently, structural detail on the CagT4SS has been substantially improved by cryo-EM. However, important structural and functional information, in particular on protein interactions between T4SS surface proteins, and of T4SS surface proteins with other proteins, is missing. In the present study, we followed the hypothesis that H. pylori T4SS external proteins may form a surface protein assembly, together with other, non-CagT4SS proteins, which may also be essential for T4SS function. Using interaction screens of H. pylori CagT4SS surface proteins, followed by biochemical and functional characterization, we have enhanced the knowledge on protein-protein interactions of CagT4SS extracellular proteins. This also includes newly identified interactions of CagT4SS surface proteins, for instance the VirB2 homolog CagC, the VirB5 homolog CagL and the surface protein CagN of unknown function, with outer membrane proteins HopQ and HopZ. We have further identified and quantitated direct interactions of T4SS surface proteins with outer membrane proteins HopZ and HopQ, which play a role in T4SS functions, and of both HopZ and HopQ with themselves and with host cell factors CEACAM and integrin. Furthermore, we determined an influence of pH on interactions between HopQ/HopZ and CagT4SS components. Utilizing protein tag insertions in H. pylori, we detected surface-exposed association of HopQ and HopZ with T4SS components on bacteria without or with (for HopQ) human gastric epithelial cells. Functionally antagonistic roles of HopQ and HopZ were uncovered in T4SS-dependent early pro- inflammatory human epithelial cell activation. In summary, we identified a network of interactions between H. pylori outer membrane proteins and CagT4SS surface proteins and characterized them as functionally important for transport processes. This will help to refine structural and functional details regarding surface-exposed proteins of the CagT4SS.

microbiology↗

bioRxiv2025

Cross-regulation of (p)ppGpp and c-di-GMP pathways controls a cell-cycle transition

Bacteria must adapt their physiology to changing environments, a process often orchestrated by nucleotide messengers such as (p)ppGpp and cyclic di-GMP (c-di-GMP). While (p)ppGpp promotes survival under nutrient stress by suppressing growth, c-di-GMP supports sessile lifestyles and cell differentiation. In the -proteobacterium Caulobacter crescentus, these messengers have opposite effects on the cell cycle, suggesting potential cross-regulations. Here, we uncover direct molecular cross-talk between (p)ppGpp and c-di-GMP signaling pathways. Using biochemical, structural and genetic approaches, we show that (p)ppGpp binds to the diguanylate cyclase PleD and inhibits c-di-GMP synthesis by competing with GTP at the active site. This interaction prevents c-di-GMP accumulation under nutrient-limiting conditions, linking metabolic stress to inhibition of developmental progression. Our findings reveal a new paradigm for second messenger interplay, in which one messenger directly suppresses synthesis of another. This work provides insight into how bacteria integrate metabolic and developmental cues through small-molecule cross-talk to guide adaptive behavior.

microbiology↗

bioRxiv2025

Widespread repurposing of the human CD38 ADP-ribosyl cyclase fold for toxicity in antibacterial and anti-eukaryotic bacterial polymorphic toxins

Bacterial polymorphic toxins are modular weapons that mediate inter-microbial competition and host interactions by delivering diverse cytotoxic domains through specialized secretion systems. Here, we identify and characterize a novel toxin domain in Pantoea ananatis that displays remarkable structural and functional conservation with the human enzyme CD38. This bacterial toxin, fused to the type VI secretion system (T6SS) PAAR domain, harbors a C-terminal ADP-ribosyl cyclase (ARC) domain that hydrolyzes NAD+ and NADP+ in vitro and in vivo, leading to growth inhibition in both bacterial and eukaryotic cells. The 1.6-[A] resolution structure of ARC reveals that it adopts a globular fold nearly identical to the human CD38 ADP ribosyl cyclase, with key catalytic residues conserved. ARC toxicity is neutralized in P. ananatis by a dedicated immunity protein. Comparative genomics reveals that CD38-like ARC domains are widespread in bacteria, fused to diverse delivery modules including T6SS, T7SS, and CDI systems. Functional assays demonstrate that these domains act as NAD-depleting toxins, with cross-immunity observed between non-cognate toxin-immunity pairs. Taken together, our findings reveal that a eukaryotic-like NAD+ hydrolase fold has been adapted in bacteria to generate a novel class of metabolic toxins, expanding the functional scope of polymorphic effectors and illustrating how conserved host-like enzymes can be co-opted for microbial warfare.

microbiology↗

bioRxiv2021

The unique Brucella effectors NyxA and NyxB target SENP3 to modulate the subcellular localisation of nucleolar proteins

The cell nucleus is a primary target for intracellular bacterial pathogens to counteract immune responses and hijack host signalling pathways to cause disease. The mechanisms controlling nuclear protein localisation in the context of stress responses induced upon bacterial infection are still poorly understood. Here we show that the Brucella abortus effectors NyxA and NyxB interfere with the host sentrin specific protease 3 (SENP3), which is essential for intracellular replication. Translocated Nyx effectors directly interact with SENP3 via a defined acidic patch identified from the crystal structure of NyxB, preventing its nucleolar localisation at the late stages of the infection. By sequestering SENP3, the Nyx effectors induce the cytoplasmic accumulation of the nucleolar AAA-ATPase NVL, the large subunit ribosomal protein L5 (RPL5) and the ribophagy receptor NUFIP1 in Nyx-enriched structures in the vicinity of replicating bacteria. This shuttling of ribosomal biogenesis-associated nucleolar proteins is negatively regulated by SENP3 and dependent on the autophagy-initiation protein Beclin1, indicative of a ribophagy-derived process induced during Brucella infection. Our results highlight a new nucleomodulatory function by two unique Brucella effectors, and reveal that SENP3 is a critical regulator of the subcellular localisation of multiple nucleolar proteins during Brucella infection, promoting intracellular replication.

microbiology↗