structures of the Dot/Icm T4SS identify the DotA-IcmX complex as the gatekeeper for effector translocation.

The Dot/Icm machine in is one of the most versatile type IV secretion systems (T4SSs), with a remarkable capacity to translocate over 330 different effector proteins across the bacterial envelope into host cells. At least 27 Dot and Icm proteins are required for assembly and function of the system, yet the architecture and activation mechanism remain poorly understood at the molecular level. Here, we deploy cryo-electron microscopy to reveal structures of the Dot/Icm machine at near-atomic resolution.

Saccharibacteria deploy two distinct type IV pili, driving episymbiosis, host competition, and twitching motility.

All cultivated Patescibacteria, also known as the candidate phyla radiation, are obligate episymbionts residing on other microbes. Despite being ubiquitous in many diverse environments, including mammalian microbiomes, molecular mechanisms of host identification and binding amongst ultrasmall bacterial episymbionts remain largely unknown. Type 4 pili are well conserved in this group and could potentially facilitate these symbiotic interactions.

FlgY, PflA, and PflB form a spoke-ring network in the high-torque flagellar motor of .

has evolved distinct flagellar motility to colonize the human stomach. Rotation of the flagella is driven by one of the largest known bacterial flagellar motors. In addition to the core motor components found in and , the flagellar motor in possesses many accessories that enable the bacteria to penetrate the gastric mucus layer.

The architecture, assembly, and evolution of a complex flagellar motor.

Bacterial flagella drive motility in many species, likely including the last bacterial common ancestor . Knowledge of flagellar assembly and function has mainly come from studies of and , which have simple flagellar motors . However, most flagellated bacteria possess complex motors with unique, species-specific adaptations whose mechanisms and evolution remain largely unexplored .

FlbB forms a distinctive ring essential for periplasmic flagellar assembly and motility in Borrelia burgdorferi.

Spirochetes are a widespread group of bacteria with a distinct morphology. Some spirochetes are important human pathogens that utilize periplasmic flagella to achieve motility and host infection. The motors that drive the rotation of periplasmic flagella have a unique spirochete-specific feature, termed the collar, crucial for the flat-wave morphology and motility of the Lyme disease spirochete Borrelia burgdorferi.

Saccharibacteria deploy two distinct Type IV pili, driving episymbiosis, host competition, and twitching motility.

All cultivated Patescibacteria, or CPR, exist as obligate episymbionts on other microbes. Despite being ubiquitous in mammals and environmentally, molecular mechanisms of host identification and binding amongst ultrasmall bacterial episymbionts are largely unknown. Type 4 pili (T4P) are well conserved in this group and predicted to facilitate symbiotic interactions.

Elucidating bacterial coaggregation through a physicochemical and imaging surface characterization.

Bacterial coaggregation is a highly specific type of cell-cell interaction, well-documented among oral bacteria, and involves specific characteristics of the cell surface of the coaggregating strains. However, the understanding of the mechanisms promoting coaggregation in aquatic systems remains limited. This gap is critical to address, given the broad implications of coaggregation for multispecies biofilm formation, water quality, the performance of engineered systems, and diverse biotechnological applications.

FlgV forms a flagellar motor ring that is required for optimal motility of Helicobacter pylori.

Flagella-driven motility is essential for Helicobacter pylori to colonize the human stomach, where it causes a variety of diseases, including chronic gastritis, peptic ulcer disease, and gastric cancer. H. pylori has evolved a high-torque-generating flagellar motor that possesses several accessories not found in the archetypical Escherichia coli motor.

Control of the flagellation pattern in by FlhF and FlhG.

FlhF and FlhG control the location and number of flagella, respectively, in many polar-flagellated bacteria. The roles of FlhF and FlhG are not well characterized in bacteria that have multiple polar flagella, such as . Deleting in shifted the flagellation pattern where most cells had approximately four flagella to a wider and more even distribution in flagellar number.

The History of Thalidomide.

The first paper describing the pharmacological actions of thalidomide was published in 1956. The drug, then designated as K17, was thought to have sedative effects superior to those of comparator drugs and was thought to be virtually nontoxic. Only 2 years after thalidomide's launch as Contergan in Germany, it's alleged lack of toxicity came into question, with reports of the drug causing numerous side effects.