Biology subjects

Damke, P. P.

Publications and source records attributed to Damke, P. P..

3 recordsLinked to original sources

bioRxiv2023

Architectural asymmetry enables DNA transport through the Helicobacter pylori cag type IV secretion system

Structural asymmetry within secretion system architecture is fundamentally important for apparatus diversification and biological function. However, the mechanism by which symmetry mismatch contributes to nanomachine assembly and interkingdom effector translocation are undefined. Here, we show that architectural asymmetry orchestrates dynamic substrate selection and enables trans-kingdom DNA conjugation through the Helicobacter pylori cag type IV secretion system (cag T4SS). Structural analyses of asymmetric units within the cag T4SS periplasmic ring complex (PRC) revealed intermolecular {pi}-{pi} stacking interactions that coordinate DNA binding and license trans-kingdom conjugation without disrupting the translocation of protein and peptidoglycan effector molecules. Additionally, we identified a novel proximal translocation channel gating mechanism that regulates cargo loading and governs substrate transport across the outer membrane. We thus propose a model whereby the organization and geometry of architectural symmetry mismatch exposes {pi}-{pi} interfaces within the PRC to facilitate DNA transit through the cag T4SS translocation channel.

microbiology↗

bioRxiv2022

Helicobacter pylori provokes STING immunosurveillance via trans-kingdom conjugation

Recognition of foreign nucleic acids is an evolutionarily conserved mechanism by which the host detects microbial threats. Whereas some intracellular bacterial pathogens trigger DNA surveillance pathways following phagosomal membrane perturbation, mechanisms by which extracellular bacteria activate cytosolic nucleic acid reconnaissance systems remain unresolved. Here, we demonstrate that Helicobacter pylori exploits cag type IV secretion system (cag T4SS) activity to provoke STING signaling in gastric epithelial cells. We provide direct evidence that chromosomal fragments delivered to the host cell cytoplasm via trans-kingdom conjugation bind and activate the key DNA sensor cGMP-AMP synthase. To enable paracrine-like signal amplification, translocated H. pylori DNA is sorted into exosomes that stimulate DNA-sensing pathways in uninfected bystander cells. We show that DNA cargo is loaded into the cag T4SS apparatus in the absence of host cell contact to establish a ready-to-fire nanomachine and provide evidence that cag T4SS-dependent DNA translocation is mechanistically coupled to chromosomal replication and replichore decatenation. Collectively, these studies suggest that H. pylori evolved mechanisms to stimulate nucleic acid surveillance pathways that regulate both pro- and anti-inflammatory programs to facilitate chronic persistence in the gastric niche.

microbiology↗

bioRxiv2021

ComF is a key mediator in single-stranded DNA transport and handling during natural transformation

Natural transformation plays a major role in the spreading of antibiotic resistances and virulence factors. Whilst bacterial species display specificities in the molecular machineries allowing transforming DNA capture and integration into their genome, the ComF(C) protein is essential for natural transformation in all Gram-positive and - negative species studied. Despite this, its role remains largely unknown. Here, we show that Helicobacter pylori ComF is not only involved in DNA transport through the cell membrane, but it also required for the handling of the ssDNA once it is delivered into the cytoplasm. ComF crystal structure revealed the presence of a zinc-finger motif and a putative phosphoribosyl transferase domain, both necessary for its in vivo activity. ComF is a membrane-associated protein with affinity for single-stranded DNA. Collectively, our results suggest that ComF provides the link between the transport of the transforming DNA into the cytoplasm and its handling by the recombination machinery.

microbiology↗