Table of Contents
Spotlight
Research Articles
Research ArticleCoxiella burnetii RpoS Regulates Genes Involved in Morphological Differentiation and Intracellular GrowthThe Q fever bacterium Coxiella burnetii has spore-like environmental stability, a characteristic that contributes to its designation as a potential bioweapon. Stability is likely conferred by a highly resistant, small cell variant (SCV) stationary-phase form that arises during a biphasic developmental cycle. Here, we define the role of the alternative sigma factor...
Research Article | SpotlightPseudomonas aeruginosa Can Inhibit Growth of Streptococcal Species via Siderophore ProductionCystic fibrosis (CF) lung infections are increasingly recognized for their polymicrobial nature. These polymicrobial infections may alter the biology of the organisms involved in CF-related infections, leading to changes in growth, virulence, and/or antibiotic tolerance, and could thereby affect patient health and response to treatment. In this study, we demonstrate interactions between...
Research ArticleSpoIVA-SipL Complex Formation Is Essential for Clostridioides difficile Spore AssemblyThe metabolically dormant spore form of the major nosocomial pathogen Clostridioides difficile is its major infectious particle. However, the mechanisms controlling the formation of this resistant cell type are not well understood, particularly with respect to its outermost layer, the spore coat. We previously identified two spore-morphogenetic proteins in...
Research ArticleRoles of Bacillus subtilis RecA, Nucleotide Excision Repair, and Translesion Synthesis Polymerases in Counteracting Cr(VI)-Promoted DNA DamageIt has been shown that, following permeation of cell barriers, Cr(VI) kills B. subtilis cells following a mechanism of reactive oxygen species-promoted DNA damage, which is counteracted by the guanine oxidized repair system. Here we report a distinct mechanism of Cr(VI)-promoted DNA damage that involves production of DPCs capable of eliciting the bacterial SOS...
Research ArticleThe Nitrogen Regulator GlnR Directly Controls Transcription of the prpDBC Operon Involved in Methylcitrate Cycle in Mycobacterium smegmatisThe success of mycobacteria survival in macrophage depends on its ability to assimilate fatty acids and cholesterol from the host. The cholesterol and fatty acids are catabolized via β-oxidation to generate propionyl coenzyme A (propionyl-CoA), which is then primarily metabolized via the methylcitrate cycle. Here, we found a typical GlnR binding box in the prp operon, and the affinity is much stronger than that of PrpR, a...
Research ArticleSlyA and HilD Counteract H-NS-Mediated Repression on the ssrAB Virulence Operon of Salmonella enterica Serovar Typhimurium and Thus Promote Its Activation by OmpRThe global regulator H-NS represses the expression of acquired genes and thus avoids possible detrimental effects on bacterial fitness. Regulatory mechanisms are adapted to induce expression of the acquired genes in particular niches to obtain a benefit from the information encoded in the foreign DNA, as for pathogenesis. Here, we show two mechanisms that were integrated for the expression of virulence genes in...
Research ArticleMechanisms of Resistance to the Contact-Dependent Bacteriocin CdzC/D in Caulobacter crescentusBacteriocins are commonly used by bacteria to kill neighboring cells that compete for resources. Although most bacteriocins are secreted, the aquatic, oligotrophic bacterium Caulobacter crescentus produces a two-peptide bacteriocin, CdzC/D, that remains attached to the outer membranes of cells, enabling contact-dependent killing of cells lacking the immunity protein...
Research Article | SpotlightIdentification of a Fifth Antibacterial Toxin Produced by a Single Bacteroides fragilis StrainThe intestinal microbiota is a diverse microbial ecosystem that provides numerous benefits to humans. The factors that govern its establishment and stability are just beginning to be elucidated. Identification and characterization of antimicrobial toxins produced by its members and their killing range are essential to understanding the role of antagonism in community composition and stability. Here, we identify a fifth antimicrobial...
Research ArticleOrganization of the Flagellar Switch Complex of Bacillus subtilisFlagellar motility plays key roles in the survival of many bacteria and in the harmful action of many pathogens. Bacterial flagella rotate; the direction of flagellar rotation is controlled by a multisubunit protein complex termed the switch complex. This complex has been extensively studied in Gram-negative model species, but little is known about the complex in Bacillus...
Research ArticleRoles of the DedD Protein in Escherichia coli Cell ConstrictionCell division (cytokinesis) is a fundamental biological process that is incompletely understood for any organism. Division of bacterial cells relies on a ring-like machinery called the septal ring or divisome that assembles along the circumference of the mother cell at the site where constriction eventually occurs. In the well-studied bacterium Escherichia coli, this...
Research ArticleInactivation of cysL Inhibits Biofilm Formation by Activating the Disulfide Stress Regulator Spx in Bacillus subtilisBacillus subtilis has been studied as a model organism for biofilm formation. In this study, I explored why the cysL deletion mutant was defective in biofilm formation. I demonstrated that the ΔcysL mutation activated the disulfide stress response regulator Spx, which inhibits biofilm formation by repressing biofilm matrix genes. Homologs of Spx are...
Research ArticleDefining the Role of the Streptococcus agalactiae Sht-Family Proteins in Zinc Acquisition and Complement EvasionThis study examined the role of the two streptococcal histidine triad (Sht) proteins of Streptococcus agalactiae in zinc homeostasis and complement resistance. We showed that Sht and ShtII facilitate zinc homeostasis in conjunction with the metal-binding proteins Lmb and AdcAII. Here, we show that the Sht-family proteins are functionally redundant with overlapping...
Research ArticleGenetics behind the Biosynthesis of Nonulosonic Acid-Containing Lipooligosaccharides in Campylobacter coliDespite the fact that Campylobacter coli a major foodborne pathogen, its glycobiology has been largely neglected. The genetic makeup of the C. coli lipooligosaccharide biosynthesis locus was largely unknown until recently. C. coli...
Research ArticleExperimental Evolution of Extreme Resistance to Ionizing Radiation in Escherichia coli after 50 Cycles of SelectionSome bacterial species exhibit astonishing resistance to ionizing radiation, with Deinococcus radiodurans being the archetype. As natural IR sources rarely exceed mGy levels, the capacity of Deinococcus to survive 5,000 Gy has been attributed to desiccation resistance. To understand the molecular basis of true extreme IR resistance, we are using experimental...
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Commentary
The cytoplasmic C ring of the bacterial flagellum is known as the switch complex. It binds the response regulator phospho-CheY to control the direction of flagellar rotation.