mutants cause hyperinflammatory responses during chronic infection.

Unlabelled: infects roughly half the world's population, causing gastritis, peptic ulcers, and gastric cancer in a subset. These pathologies occur in response to a chronic inflammatory state, but it is not fully understood how controls this process. We characterized the inflammatory response of mutants that cannot produce the quorum sensing molecule autoinducer 2 (AI-2) by deleting the gene for the AI-2 synthase, .

Determination of Protein-Ligand Binding Affinities by Thermal Shift Assay.

Quantification of protein-ligand interactions is crucial for understanding the protein's biological function and for drug discovery. In this study, we employed three distinct approaches for determination of protein-ligand binding affinities by a thermal shift assay using a single ligand concentration. We present the results of the comparison of the performance of the conventional curve fitting (CF) method and two newly introduced methods - assuming zero heat capacity change across small temperature ranges (ZHC) and utilizing the unfolding equilibrium constant (UEC); the latter has the advantage of reducing calculations by obtaining the unfolding equilibrium constant directly from the experimental data.

Counterclockwise rotation of the flagellum promotes biofilm initiation in .

Unlabelled: Motility promotes biofilm initiation during the early steps of this process: microbial surface association and attachment. Motility is controlled in part by chemotaxis signaling, so it seems reasonable that chemotaxis may also affect biofilm formation. There is a gap, however, in our understanding of the interactions between chemotaxis and biofilm formation, partly because most studies analyzed the phenotype of only a single chemotaxis signaling mutant, e.

mutants recover semisolid agar migration due to loss of a previously uncharacterized Type IV filament membrane alignment complex homolog.

Unlabelled: The bacterial chemotaxis system is a well-understood signaling pathway that promotes bacterial success. Chemotaxis systems comprise chemoreceptors and the CheA kinase, linked by CheW or CheV scaffold proteins. Scaffold proteins provide connections between chemoreceptors and CheA and also between chemoreceptors to create macromolecular arrays.

Bacterial flagella hijack type IV pili proteins to control motility.

Bacterial flagella and type IV pili (TFP) are surface appendages that enable motility and mechanosensing through distinct mechanisms. These structures were previously thought to have no components in common. Here, we report that TFP and some flagella share proteins PilO, PilN, and PilM, which we identified as part of the flagellar motor.

Altering under-represented DNA sequences elevates bacterial transformation efficiency.

Manipulating the genomes of bacteria is critical to many fields. Such manipulations are made by genetic engineering, which often requires new pieces of DNA to be added to the genome. Bacteria have robust systems for identifying and degrading new DNA, some of which rely on restriction enzymes.

Discovery of Type IV filament membrane alignment complex homologs in that promote soft-agar migration.

The stomach pathogen utilizes two scaffold proteins, CheW and CheV1, to build critical chemotaxis arrays. Chemotaxis helps bacteria establish and maintain infection. Mutants lacking either of these chemotaxis proteins have different soft agar phenotypes: deletion of creates non-chemotactic strains, while deletion of results in 50% loss of chemotaxis.

Helicobacter pylori initiates successful gastric colonization by utilizing L-lactate to promote complement resistance.

The complement system has long been appreciated for its role in bloodborne infections, but its activities in other places, including the gastrointestinal tract, remain elusive. Here, we report that complement restricts gastric infection by the pathogen Helicobacter pylori. This bacterium colonized complement-deficient mice to higher levels than wild-type counterparts, particularly in the gastric corpus region.

FliL Functions in Diverse Microbes to Negatively Modulate Motor Output via Its N-Terminal Region.

The flagellar motor protein FliL is conserved across many microbes, but its exact role has been obscured by varying mutant phenotypes. We reanalyzed results from studies and found they utilized alleles that differed in the amount of N- and C-terminal regions that were retained. Alleles that retain the N-terminal cytoplasmic and transmembrane helix (TM) regions in the absence of the C-terminal periplasmic domain result in loss of motility, while alleles that completely lack the N-terminal region, independent of the periplasmic domain, retain motility.

Helicobacter pylori Chronic-Stage Inflammation Undergoes Fluctuations That Are Altered in Mutants.

Helicobacter pylori colonizes half of the world's population and is responsible for a significant disease burden by causing gastritis, peptic ulcers, and gastric cancer. The development of host inflammation drives these diseases, but there are still open questions in the field about how H. pylori controls this process.

Methylation-Independent Chemotaxis Systems Are the Norm for Gastric-Colonizing Species.

Many bacteria and archaea rely on chemotaxis signal transduction systems for optimal fitness. These complex, multiprotein signaling systems have core components found in all chemotactic microbes, as well as variable proteins found in only some species. We do not yet understand why these variations exist or whether there are specific niches that favor particular chemotaxis signaling organization.

The flagellar motor protein FliL forms a scaffold of circumferentially positioned rings required for stator activation.

The flagellar motor stator is an ion channel nanomachine that assembles as a ring of the MotAMotB units at the flagellar base. The role of accessory proteins required for stator assembly and activation remains largely enigmatic. Here, we show that one such assembly factor, the conserved protein FliL, forms an integral part of the flagellar motor in a position that colocalizes with the stator.

The dCache Chemoreceptor TlpA of Helicobacter pylori Binds Multiple Attractant and Antagonistic Ligands via Distinct Sites.

The Helicobacter pylori chemoreceptor TlpA plays a role in dampening host inflammation during chronic stomach colonization. TlpA has a periplasmic dCache_1 domain, a structure that is capable of sensing many ligands; however, the only characterized TlpA signals are arginine, bicarbonate, and acid. To increase our understanding of TlpA's sensing profile, we screened for diverse TlpA ligands using ligand binding arrays.

Genetic requirements and transcriptomics of Helicobacter pylori biofilm formation on abiotic and biotic surfaces.

Biofilm growth is a widespread mechanism that protects bacteria against harsh environments, antimicrobials, and immune responses. These types of conditions challenge chronic colonizers such as Helicobacter pylori but it is not fully understood how H. pylori biofilm growth is defined and its impact on H.

Gastric Metabolomics Detects Helicobacter pylori Correlated Loss of Numerous Metabolites in Both the Corpus and Antrum.

is a chronic bacterial pathogen that thrives in several regions of the stomach, causing inflammation that can vary by site and result in distinct disease outcomes. Whether the regions differ in terms of host-derived metabolites is not known. We thus characterized the regional variation of the metabolomes of mouse gastric corpus and antrum organoids and tissue.

Biofilm Confers Antibiotic Tolerance in Part via A Protein-Dependent Mechanism.

, a WHO class I carcinogen, is one of the most successful human pathogens colonizing the stomach of over 4.4 billion of the world's population. Antibiotic therapy represents the best solution but poor response rates have hampered the elimination of .

Helicobacter pylori Uses the TlpB Receptor To Sense Sites of Gastric Injury.

is a pathogen that chronically colonizes the stomachs of approximately half of the world's population and contributes to the development of gastric inflammation. We demonstrated previously that uses motility to preferentially colonize injury sites in the mouse stomach. However, the chemoreceptor responsible for sensing gastric injury has not yet been identified.

Control of bacterial colonization in the glands and crypts.

The epithelial cell layer of the major organs of the mammalian gastrointestinal (GI) tract is extensively invaginated into thousands of gland and crypt structures. These are lined by distinct sets of epithelial cells and may comprise discrete niches. The host maximizes the distance between the epithelial cell layer and GI-inhabiting microbes to limit inflammation, and these strategies also likely keep bacteria out of the glands and crypts.

Helicobacter pylori Biofilm Involves a Multigene Stress-Biased Response, Including a Structural Role for Flagella.

has an impressive ability to persist chronically in the human stomach. Similar characteristics are associated with biofilm formation in other bacteria. The biofilm process, however, is poorly understood.

Three SpoA-domain proteins interact in the creation of the flagellar type III secretion system in .

Bacterial flagella are rotary nanomachines that contribute to bacterial fitness in many settings, including host colonization. The flagellar motor relies on the multiprotein flagellar motor-switch complex to govern flagellum formation and rotational direction. Different bacteria exhibit great diversity in their flagellar motors.