Structural and Functional Insights into the Delivery Systems of and Clostridial Binary Toxins.

Pathogenic and clostridial (i.e., and ) bacteria express a diverse repertoire of effector proteins to promote disease.

Metagenome diversity illuminates the origins of pathogen effectors.

Recent metagenome-assembled genome (MAG) analyses have profoundly impacted Rickettsiology systematics. The discovery of basal lineages (novel families Mitibacteraceae and Athabascaceae) with predicted extracellular lifestyles exposed an evolutionary timepoint for the transition to host dependency, which seemingly occurred independent of mitochondrial evolution. Notably, these basal rickettsiae carry the Rickettsiales homolog () type IV secretion system and purportedly use to kill congener microbes rather than parasitize host cells as described for later-evolving rickettsial pathogens.

Divergent LpxO enzymes perform site-specific lipid A 2-hydroxylation.

can survive in a myriad of environments, partially due to modifications of its lipid A, the membrane anchor of lipopolysaccharide. We previously demonstrated that divergent late acyltransferase paralogs, HtrB1 and HtrB2, add acyloxyacyl laurate to lipid A 2- and 2'-acyl chains, respectively. The genome of also has genes which encode two dioxygenase enzymes, LpxO1 and LpxO2, that individually hydroxylate a specific secondary laurate.

Structural determination of lipid A without chemical extraction confirms shorter acyl chains in later-evolving Spotted Fever Group pathogens.

Unlabelled: Rickettsiae are Gram-negative obligate intracellular parasites of numerous eukaryotes. Human pathogens of the Transitional Group (TRG), Typhus Group (TG), and Spotted Fever Group (SFG) rickettsiae infect blood-feeding arthropods, have dissimilar clinical manifestations, and possess unique genomic and morphological attributes. Lacking glycolysis, rickettsiae pilfer numerous metabolites from host cytosol to synthesize peptidoglycan and lipopolysaccharide (LPS).

analysis of the mobilome of a highly fragmented and repetitive genome reveals ongoing lateral gene transfer in an obligate intracellular bacterium.

The rickettsial human pathogen (Ot) is an obligate intracellular Gram-negative bacterium with one of the most highly fragmented and repetitive genomes of any organism. Around 50% of its ~2.3 Mb genome is comprised of repetitive DNA that is derived from the highly proliferated Rickettsiales amplified genetic element (RAGE).

Orientia and Rickettsia: different flowers from the same garden.

Recent discoveries of basal extracellular Rickettsiales have illuminated divergent evolutionary paths to host dependency in later-evolving lineages. Family Rickettsiaceae, primarily comprised of numerous protist- and invertebrate-associated species, also includes human pathogens from two genera, Orientia and Rickettsia. Once considered sister taxa, these bacteria form distinct lineages with newly appreciated lifestyles and morphological traits.

Metagenome diversity illuminates origins of pathogen effectors.

Recent metagenome assembled genome (MAG) analyses have profoundly impacted Rickettsiology systematics. Discovery of basal lineages (Mitibacteraceae and Athabascaceae) with predicted extracellular lifestyles reveals an evolutionary timepoint for the transition to host dependency, which occurred independent of mitochondrial evolution. Notably, these basal rickettsiae carry the Rickettsiales homolog () type IV secretion system (T4SS) and purportedly use to kill congener microbes rather than parasitize host cells as described for derived rickettsial pathogens.

Cryptic Genes for Interbacterial Antagonism Distinguish Species Infecting Blacklegged Ticks From Other Pathogens.

Background: The genus (: Rickettsiales) encompasses numerous obligate intracellular species with predominantly ciliate and arthropod hosts. Notable species are pathogens transmitted to mammals by blood-feeding arthropods. Mammalian pathogenicity evolved from basal, non-pathogenic host-associations; however, some non-pathogens are closely related to pathogens.

Genome sequencing of Pseudomonas aeruginosa strain M2 illuminates traits of an opportunistic pathogen of burn wounds.

Pseudomonas aeruginosa is a Gram-negative nosocomial pathogen and one of the most prevalent organisms isolated from burn wounds worldwide. Pseudomonas aeruginosa strain M2 (O5 serotype, type B flagella) is utilized for examining the murine model associated with burns. Pseudomonas aeruginosa M2 is similar in lethality to common laboratory P.

Discovery of a Diverse Set of Bacteria That Build Their Cell Walls without the Canonical Peptidoglycan Polymerase aPBP.

Peptidoglycan (PG) is a highly cross-linked peptide-glycan mesh that confers structural rigidity and shape to most bacterial cells. Polymerization of new PG is usually achieved by the concerted activity of two membrane-bound machineries, class-A penicillin binding proteins (aPBPs) and class-B penicillin binding proteins (bPBPs) in complex with shape, elongation, division, and sporulation (SEDS) proteins. Here, we have identified four phylogenetically distinct groups of bacteria that lack any identifiable aPBPs.

Lipid A Structural Divergence in Pathogens.

Species of (: ) are obligate intracellular parasites of a wide range of eukaryotes, with recognized arthropod-borne human pathogens belonging to the transitional group (TRG), typhus group (TG), and spotted fever group (SFG) rickettsiae. Growing in the host cytosol, rickettsiae pilfer numerous metabolites to make a typical Gram-negative bacterial cell envelope. The O-antigen of rickettsial lipopolysaccharide (LPS) is immunogenic and has been shown to tether the S-layer to the rickettsial surface; however, little is known about the structure and immunogenicity of the lipid A moiety.

The complete mitochondrial genome of the cat flea, .

The cat flea, , is widely recognized as a global veterinary pest and a vector of pathogenic bacteria. We recently reported on the . nuclear genome, which is characterized by over 38% protein coding gene duplication, extensive tRNA gene family expansion, and remarkable gene copy number variation (CNV) between individual fleas.

Evolution of mutualism and reproductive parasitism: insight from two novel strains that co-infect cat fleas.

Wolbachiae are obligate intracellular bacteria that infect arthropods and certain nematodes. Usually maternally inherited, they may provision nutrients to (mutualism) or alter sexual biology of (reproductive parasitism) their invertebrate hosts. We report the assembly of closed genomes for two novel wolbachiae, CfeT and CfeJ, found co-infecting cat fleas () of the Elward Laboratory colony (Soquel, CA, USA).

The Impact of Robotic-Assisted Surgery on Team Performance: A Systematic Mixed Studies Review.

Objective: The aim of this study is to describe the impact of robotic-assisted surgery on team performance in the operating room.

Background: The introduction of surgical robots has improved the technical performance of surgical procedures but has also contributed to unexpected interactions in surgical teams, leading to new types of errors.

Method: A systematic literature search of Cumulative Index to Nursing and Allied Health Literature, PubMed, ProQuest, Cochrane, Web of Science, PsycINFO, and Scopus databases using key words and MeSH terms was conducted.

A chromosome-level assembly of the cat flea genome uncovers rampant gene duplication and genome size plasticity.

Background: Fleas (Insecta: Siphonaptera) are small flightless parasites of birds and mammals; their blood-feeding can transmit many serious pathogens (i.e., the etiological agents of bubonic plague, endemic and murine typhus).

Risk1, a Phosphatidylinositol 3-Kinase Effector, Promotes Rickettsia typhi Intracellular Survival.

To establish a habitable intracellular niche, various pathogenic bacteria secrete effectors that target intracellular trafficking and modulate phosphoinositide (PI) metabolism. Murine typhus, caused by the obligate intracellular bacterium , remains a severe disease in humans. However, the mechanisms by which effector molecules contribute to internalization by induced phagocytosis and subsequent phagosomal escape into the cytosol to facilitate the intracellular growth of the bacteria remain ill-defined.

Conjugative Transposons and Their Cargo Genes Vary across Natural Populations of Rickettsia buchneri Infecting the Tick Ixodes scapularis.

Rickettsia buchneri (formerly Rickettsia endosymbiont of Ixodes scapularis, or REIS) is an obligate intracellular endoparasite of the black-legged tick, the primary vector of Lyme disease in North America. It is noteworthy among the rickettsiae for its relatively large genome (1.8 Mb) and extraordinary proliferation of mobile genetic elements (MGEs), which comprise nearly 35% of its genome.

A Tangled Web: Origins of Reproductive Parasitism.

While typically a flea parasite and opportunistic human pathogen, the presence of Rickettsia felis (strain LSU-Lb) in the non-blood-feeding, parthenogenetically reproducing booklouse, Liposcelis bostrychophila, provides a system to ascertain factors governing not only host transitions but also obligate reproductive parasitism (RP). Analysis of plasmid pLbAR, unique to R. felis str.

Rickettsia Lipid A Biosynthesis Utilizes the Late Acyltransferase LpxJ for Secondary Fatty Acid Addition.

Members of the genus are obligate intracellular, Gram-negative coccobacilli that infect mammalian and arthropod hosts. Several rickettsial species are human pathogens and are transmitted by blood-feeding arthropods. In Gram-negative parasites, the outer membrane (OM) sits at the nexus of the host-pathogen interaction and is rich in lipopolysaccharide (LPS).

The Rickettsial Ankyrin Repeat Protein 2 Is a Type IV Secreted Effector That Associates with the Endoplasmic Reticulum.

Strains of , the tick-borne agent of Rocky Mountain spotted fever, vary considerably in virulence. Genomic comparisons of strains have identified a relatively small number of genes divergent in an avirulent strain. Among these is one annotated as ankyrin repeat protein 2 (RARP-2).

The Cat Flea (Ctenocephalides felis) Immune Deficiency Signaling Pathway Regulates Rickettsia typhi Infection.

species are obligate intracellular bacteria with both conserved and lineage-specific strategies for invading and surviving within eukaryotic cells. One variable component of biology involves arthropod vectors: for instance, typhus group rickettsiae are principally vectored by insects (i.e.

Wholly ! Reconstructed Metabolic Profile of the Quintessential Bacterial Parasite of Eukaryotic Cells.

Reductive genome evolution has purged many metabolic pathways from obligate intracellular (; ). While some aspects of host-dependent rickettsial metabolism have been characterized, the array of host-acquired metabolites and their cognate transporters remains unknown. This dearth of information has thwarted efforts to obtain an axenic culture, a major impediment to conventional genetic approaches.