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Journal of Bacteriology

Itai Muzhingi, Cecilia Prado, Mariame Sylla, Frances F Diehl, Duy K Nguyen, Mariah M Servos, Stephany Flores Ramos, Alexandra E Purdy
Vibrio cholerae controls the pathogenicity of interactions with arthropod hosts via the activity of the CrbS/R two component system. This signaling pathway regulates the consumption of acetate, which in turn, alters the relative virulence of interactions with arthropods, including Drosophila melanogaster CrbS is a histidine kinase that links a transporter-like domain to its signaling apparatus via putative STAC and PAS domains. CrbS and its cognate response regulator are required for expression of acetyl-CoA synthetase ( acs ), which converts acetate to acetyl-CoA...
September 17, 2018: Journal of Bacteriology
Evelyn Sun, Sijie Liu, Robert E W Hancock
Bacterial rapid surfing motility is a novel surface adaptation of Pseudomonas aeruginosa in the presence of the glycoprotein, mucin. Here we show that other Gram-negative motile bacterial species including Escherichia coli , Salmonella enterica , Vibrio harveyi , Enterobacter cloacae , and Proteus mirabilis also exhibit the physical characteristics of surfing on the surface of agar plates containing 0.4% mucin, wherein surfing motility was generally more rapid and less dependent on medium viscosity than swimming motility...
September 17, 2018: Journal of Bacteriology
Kimberly McCullor, Brandon Postoak, Maliha Rahman, Catherine King, W Michael McShan
Lytic bacteriophage A25, which infects Streptococcus pyogenes and several related species, has been used to better understand phage-microbial interactions due to its ability to mediate high efficiency transduction. Most of these studies, however, are decades old and were conducted prior to the advent of next generation sequencing and bioinformatics. The aim of our study was to gain a better understanding of the mechanism of high efficiency transduction through analysis of the A25 genome. We show here that phage A25 is related to a family of genome prophages and became a lytic phage following escape from lysogeny...
September 17, 2018: Journal of Bacteriology
G Keb, R Hayman, K A Fields
As obligate intracellular bacteria, Chlamydia spp. have evolved numerous-likely intricate- mechanisms to create and maintain a privileged intracellular niche. Recent progress in elucidating and characterizing these processes has been bolstered by the development of techniques enabling basic genetic tractability. Florescence-reported allelic exchange mutagenesis (FRAEM) couples chromosomal gene deletion with insertion of a selection cassette encoding antibiotic resistance and GFP. Similar to other bacteria, many chlamydial genes exist within polycistronic operons, raising the possibility of polar effects mediated by insertion cassettes...
September 17, 2018: Journal of Bacteriology
Fabian M Commichau, Jana L Heidemann, Ralf Ficner, Jörg Stülke
Cyclic di-AMP is a second messenger nucleotide that is produced by many bacteria and some archaea. Recent work has shown that c-di-AMP is unique among the signaling nucleotides, as this molecule is in many bacteria both essential on one hand and toxic upon accumulation on the other. Moreover, in bacteria like Bacillus subtilis , c-di-AMP controls a biological process, potassium homeostasis, by binding both potassium transporters and riboswitch molecules in the mRNAs that encode the potassium transporters. In addition to the control of potassium homeostasis, c-di-AMP has been implicated in many cellular activities including DNA repair, cell wall homeostasis, osmotic adaptation, biofilm formation, central metabolism, and virulence...
September 17, 2018: Journal of Bacteriology
Bitan Mohari, Melene A Thompson, Jonathan C Trinidad, Sima Setayeshgar, Clay Fuqua
Rotary flagella propel bacteria through liquid and across semi-solid environments. Flagella are composed of the basal body that constitutes the motor for rotation, the curved hook that connects to the basal body, and the flagellar filament that propels the cell. Flagellar filaments can be comprised of a single flagellin protein such as in Escherichia coli or made up of multiple flagellins such as in Agrobacterium tumefaciens The four distinct flagellins FlaA, FlaB, FlaC and FlaD produced by wild type A. tumefaciens , are not redundant in function, but have specific properties...
September 10, 2018: Journal of Bacteriology
Griffin Chure, Heun Jin Lee, Akiko Rasmussen, Rob Phillips
Rapid changes in extracellular osmolarity are one of many insults microbial cells face on a daily basis. To protect against such shocks, Escherichia coli and other microbes express several types of transmembrane channels which open and close in response to changes in membrane tension. In E. coli , one of the most abundant channels is the mechanosensitive channel of large conductance (MscL). While this channel has been heavily characterized through structural methods, electrophysiology, and theoretical modeling, our understanding of its physiological role in preventing cell death by alleviating high membrane tension remains tenuous...
September 10, 2018: Journal of Bacteriology
K Karl Compton, Sherry B Hildreth, Richard F Helm, Birgit E Scharf
Sinorhizobium meliloti is a soil-dwelling endosymbiont of alfalfa with eight chemoreceptors to sense environmental stimuli during its free-living state. The functions of two receptors have been characterized, with McpU and McpX serving as general amino acid and quaternary ammonium compound sensors, respectively. Both receptors use a dual Cache domain for ligand binding. We identified that the ligand-binding, periplasmic region (PR) of McpV contains a single Cache domain. Homology modeling revealed that McpVPR is structurally similar to a sensor domain of a chemoreceptor with unknown function from Anaeromyxobacter dehalogenans , which crystallized with acetate in its binding pocket...
September 10, 2018: Journal of Bacteriology
Lívia Araújo Alves, Tridib Ganguly, Renata O Mattos-Graner, Jessica Kajfasz, Erika N Harth-Chu, José A Lemos, Jacqueline Abranches
Cnm is a surface-associated protein present in a subset of Streptococcus mutans strains that mediates binding to extracellular matrices, intracellular invasion and virulence. Here, we showed that cnm transcription is controlled by the global regulators CovR and VicRKX. In silico analysis identified multiple putative CovR- and VicR-binding motifs in the regulatory region of cnm as well as in the downstream gene pgfS , which is associated with the posttranslational modification of Cnm. Electrophoretic mobility shift assays revealed that CovR and VicR specifically and independetly bind to the cnm and pgfS promoter regions...
September 10, 2018: Journal of Bacteriology
Skyler Hebdon, Smita Menon, George B Richter-Addo, Elizabeth A Karr, Ann H West
The Clostridioides difficile R20291 genome encodes 57 response regulator proteins that, as part of two-component signaling pathways, regulate adaptation to environmental conditions. Genomic and transcriptomic studies in C. difficile have been limited, due to technical challenges, to the analysis of either high-throughput screens or high priority targets such as primary regulators of toxins or spore biology. We present the use of several technically accessible and generally applicable techniques to elucidate the putative regulatory targets of a response regulator (RR_1586) involved in sporulation of the hypervirulent C...
September 10, 2018: Journal of Bacteriology
Andrew M Burrage, Eric Vanderpool, Daniel B Kearns
Bacterial flagella contain an axle-like rod that transits the cell envelope and connects the transmembrane basal body to the extracellular hook and filament. Although the rod is a crucial component of the flagellum, its structure and assembly are poorly understood. Previous reports defining the order of rod assembly in Gram-negative bacteria suggest that the rod requires five proteins to successfully assemble but assembly intermediates have not been well characterized due to metastablity and periplasmic proteolysis...
September 10, 2018: Journal of Bacteriology
Jennifer E Kurasz, Christine E Hartman, David J Samuels, Bijoy K Mohanty, Anquilla Deleveaux, Jan Mrázek, Anna C Karls
The σ54 regulon in Salmonella enterica serovar Typhimurium includes a predicted RNA repair operon, encoding homologs of the metazoan Ro60 protein (Rsr), Y RNAs (YrlBA), RNA ligase (RtcB), and RNA 3'-phosphate cyclase (RtcA). Transcription from σ54 -dependent promoters requires that a cognate bacterial enhancer binding protein (bEBP) be activated by a specific environmental or cellular signal; the cognate bEBP for the σ54 -dependent promoter of the rsr-yrlBA-rtcBA operon is RtcR. To identify conditions that generate the signal for RtcR activation in S Typhimurium, transcription of the RNA repair operon was assayed under multiple stress conditions that result in nucleic acid damage...
September 10, 2018: Journal of Bacteriology
Y Hoang, Lee Kroos
Upon depletion of nutrients, Myxococcus xanthus forms mounds on a solid surface. The differentiation of rod-shaped cells into stress-resistant spores within mounds creates mature fruiting bodies. The developmental process can be perturbed by the addition of nutrient medium before the critical period of commitment to spore formation. The response was investigated by adding a twofold dilution series of nutrient medium to starving cells. An ultrasensitive response was observed, as indicated by a steep increase in the spore number after 12...
September 4, 2018: Journal of Bacteriology
Jing Xu, H Steven Seifert
Many pathogenic microbes evade host immune surveillance by varying surface antigens, a process termed antigenic variation. While the process of pilin antigenic variation has been extensively studied in the human pathogen Neisseria gonorrhoeae (Gc), relatively few studies of pilin antigenic variation been conducted with Neisseria meningitidis (Mc). Mc is usually a commensal organism that colonizes the human nasopharynx, but when it translocates into the blood stream or meninges, it results in the severe and often deadly meningococcal disease...
September 4, 2018: Journal of Bacteriology
Jessica Irons, Kelsey M Hodge-Hanson, Diana M Downs
The Rid protein superfamily (YjgF/YER057c/UK114) is found in all domains of life. The archetypal protein, RidA from Salmonella enterica , is a deaminase that quenches the reactive metabolite 2-aminoacrylate (2AA). 2AA deaminase activity is conserved in RidA proteins from humans, plants, yeast, archaea and bacteria. Mutants of Salmonella enterica , Escherichia coli , and Saccharomyces cerevisiae that lack a functional RidA exhibit growth defects, suggesting 2AA metabolic stress is similarly conserved. The PubSeed database shows Pseudomonas aeruginosa (PAO1) encodes eight members of the Rid superfamily...
September 4, 2018: Journal of Bacteriology
Ashwin Govindan, Sandeep Miryala, Sanjay Mondal, Umesh Varshney
Genetic analysis of the mechanism of protein synthesis in Gram positive bacteria has remained largely unexplored because of the unavailability of appropriate in vivo assay systems. We developed chloramphenicol acetyltransferase (CAT) based in vivo reporter systems to study translation initiation and elongation in Mycobacterium smegmatis The CAT reporters utilize specific decoding of amber codons by mutant initiator tRNA (i-tRNA, metU ) molecules containing a CUA anticodon ( metU CUA ). The assay systems allow structure-function analyses of tRNAs without interfering with the cellular protein synthesis, and function with or without the expression of heterologous GlnRS from Escherichia coli We show that, despite their naturally occurring slow growth phenotypes, the step of i-tRNA formylation is vital in translation initiation in mycobacteria and, that formylation deficient i-tRNA mutants ( metU CUA/A1 , metU CUA/G72 and metU CUA/G72G73 ) with a Watson-Crick base pair at 1-72 position participate in elongation...
September 4, 2018: Journal of Bacteriology
Jun-Jie Zhang, Tong Chen, Youyun Yang, Jimei Du, Hongxia Li, Bryan Troxell, Ming He, Sebastian Carrasco, Mark Gomelsky, X Frank Yang
Borrelia burgdorferi , the causative agent of Lyme disease, encounters two disparate host environments during its enzootic life cycle, Ixodes ticks and mammalian hosts. B. burgdorferi has a small genome that encodes a streamlined c-di-GMP signaling system comprising a single diguanylate cyclase Rrp1, and two phosphodiesterases. This system is essential for spirochete survival in ticks, in part, by controlling the expression of the glp operon involved in glycerol utilization. In this study, we showed that a B...
September 4, 2018: Journal of Bacteriology
Andrew I Perault, Peggy A Cotter
The respiratory tracts of individuals afflicted with cystic fibrosis (CF) harbor complex polymicrobial communities. By an unknown mechanism, species of the Gram-negative Burkholderia cepacia complex, such as Burkholderia dolosa , can displace other bacteria in the CF lung, causing cepacia syndrome, which has a poor prognosis. The genome of B. dolosa strain AU0158 ( Bd AU0158) contains three loci that are predicted to encode Contact-Dependent growth Inhibition (CDI) systems. CDI systems function by translocating the toxic C-terminus of a large exoprotein directly into target cells, resulting in growth inhibition or death unless the target cells produce a cognate immunity protein...
August 27, 2018: Journal of Bacteriology
Yu-Fan Tsao, Véronique L Taylor, Smriti Kala, Joseph Bondy-Denomy, Alima N Khan, Diane Bona, Vincent Cattoir, Stephen Lory, Alan R Davidson, Karen L Maxwell
The viruses that infect bacteria, known as phages, play critical roles in controlling bacterial populations in many diverse environments, including the human body. This control stems not only from phages killing bacteria, but also the formation of lysogens. In this state the phage replication cycle is suppressed, and the phage genome is maintained in the bacterial cell in a form known as a prophage. Prophages often carry genes that benefit the host bacterial cell since increasing survival of the host cell by extension also increases the fitness of the prophage...
August 27, 2018: Journal of Bacteriology
Jessica Horn, Maximilian Klepsch, Michelle Manger, Christiane Wolz, Thomas Rudel, Martin Fraunholz
Staphylococcus aureus is a human pathogen causing a variety of diseases by versatile expression of a large set of virulence factors, which most prominently features the cytotoxic and hemolytic pore-forming α-toxin. Expression of α-toxin is regulated by an intricate network of transcription factors. These include two-component systems sensing quorum and environmental signals as well as regulators reacting to the nutritional status of the pathogen. We previously identified repressor of surface proteins (Rsp) as virulence regulator...
August 27, 2018: Journal of Bacteriology
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