Tobacco etch virus (TEV) encodes three proteinases that catalyze processing of the genome-encoded polyprotein.
The P1 proteinase originates from the N terminus of the polyprotein and catalyzes proteolysis between
itself and the helper component proteinase (HC-Pro). Mutations resulting in substitution of a single amino
acid, small insertions, or deletions were...
The RNA genome of tobacco etch virus (TEV), a plant potyvirus, functions as an mRNA for synthesis of a
346-kilodalton polyprotein that undergoes extensive proteolytic processing. The RNA lacks a normal 5' cap
structure at its terminus, which suggests that the mechanism of translational initiation differs from that of a...
Intact core tetraether membrane lipids of marine planktonic Crenarchaeota were quantified in water column-suspended particulate matter obtained from four depth intervals (~70, 500, 1,000 and 1,500 m) at seven stations in the northwestern Arabian Sea to investigate the distribution of the organisms at various depths. Maximum concentrations generally occurred at...
Microbial communities in cores obtained from methane hydrate-bearing deep marine sediments (down to more than 300 m below the seafloor) in the forearc basin of the Nankai Trough near Japan were characterized with cultivation-dependent and -independent techniques. Acridine orange direct count data indicated that cell numbers generally decreased with sediment...
Thirty-two chemoheterotrophic bacteria were isolated from unsaturated subsurface soil samples obtained from ca. 70 m below land surface in a high desert in southeastern Idaho. Most isolates were gram positive (84%) and strict aerobes (79%). Acridine orange direct counts of microbes in one subsurface sample showed lower numbers than similar...
The bacteria colonizing geologic core sections (attached) were contrasted with those found suspended in the groundwater (unattached) by examining the microbiology of 16 depth-paired core and groundwater samples using a suite of culture-independent and culture-dependent analyses. One hundred twenty-two meters was continuously cored from a buried chalcopyrite ore hosted in...
Bacteria and algae isolated from a wastewater oxidation pond were inoculated onto opposing surfaces of double-layer agar plates (Lutri plates) to determine the usefulness of such plates for studying microbial interactions. The altered growth characteristics of various algae depending on the species of bacteria on the adjacent medium surface indicated...
There is growing interest in the application of human-associated fecal source identification quantitative real-time PCR (qPCR) technologies for water quality management. The transition from a research tool to a standardized protocol requires a high degree of confidence in data quality across laboratories. Data quality is typically determined through a series...
Nitrosomonas europaea is a chemolithoautotrophic bacterium that oxidizes ammonia (NH₃) to obtain energy for growth on carbon dioxide (CO₂) and can also produce nitrous oxide (N₂O), a greenhouse gas. We interrogated the growth, physiological, and transcriptome responses of N. europaea to conditions of replete (>5.2 mM) and limited inorganic carbon...
Ammonia oxidation is the first and rate-limiting step in nitrification and is dominated by two distinct groups of microorganisms in soil: ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). AOA are often more abundant than AOB and dominate activity in acid soils. The mechanism of ammonia oxidation under acidic conditions has...
Clostridium perfringens type A is a common source of foodborne illness (FBI) in humans. Vegetative cells sporulate in the small intestinal tract and produce the major pathogenic factor C. perfringens enterotoxin. Although sporulation plays a critical role in the pathogenesis of FBI, the mechanisms inducing sporulation remain unclear. Bile salts...
To stabilize cellular integrity in the face of environmental perturbations, most bacteria, including cyanobacteria, synthesize and maintain a strong, flexible, three-dimensional peptidoglycan lattice. Anabaena sp. strain PCC 7120 is a filamentous cyanobacterium capable of differentiating morphologically distinct nitrogen-fixing heterocyst cells in a periodic pattern. While heterocyst development has been shown...
Pseudomonas protegens strain Pf-5 is a rhizosphere bacterium that suppresses soilborne plant diseases and produces at least seven different secondary metabolites with antifungal properties. We derived mutants of Pf-5 with single and multiple mutations in biosynthesis genes for seven antifungal metabolites: 2,4-diacetylphoroglucinol (DAPG), pyrrolnitrin, pyoluteorin, hydrogen cyanide, rhizoxin, orfamide A,...
The Chloroflexi CL500-11 clade contributes a large proportion of the bacterial biomass in the oxygenated hypolimnia of deep lakes worldwide, including the world's largest freshwater system, the Laurentian Great Lakes. Traits that allow CL500-11 to thrive and its biogeochemical role in these environments are currently unknown. Here, we found that...
The direct major histocompatibility complex (MHC) class I antigen presentation pathway ensures intracellular peptides are displayed at the cellular surface for recognition of infected or transformed cells by CD8⁺ cytotoxic T lymphocytes. Chlamydia spp. are obligate intracellular bacteria and, as such, should be targeted by CD8⁺ T cells. It is...
Polymorphonuclear leukocytes (PMN) from patients with chronic granulomatous disease (CGD) fail to produce microbicidal concentrations of reactive oxygen species (ROS) due to mutations in NOX2. Patients with CGD suffer from severe, life-threatening infections and inflammatory complications. Granulibacter bethesdensis is an emerging Gram-negative pathogen in CGD that resists killing by PMN...
Five cases of bacterial meningitis treated with ceftaroline (4 Streptococcus pneumoniae and 1 Staphylococcus aureus) are summarized here. The pharmacodynamics of human cathelicidin LL-37 and ceftaroline were evaluated against S. pneumoniae. Patients who received ceftaroline 600 mg every 8 h (q8h) (1 S. aureus and 3 S. pneumoniae) were successfully...
Ebola viruses (EBOV) cause severe disease in humans and nonhuman primates with high mortality rates and continue to emerge in new geographic locations, including several countries in West Africa, the site of a large ongoing outbreak. Phosphorodiamidate morpholino oligomers (PMOs) are synthetic antisense molecules that are able to target mRNAs...
Autoinduction (AI), the response to self-produced chemical signals,
is widespread in the bacterial world. This process controls
vastly different target functions, such as luminescence, nutrient
acquisition, and biofilm formation, in different ways and integrates
additional environmental and physiological cues. This diversity
raises questions about unifying principles that underlie all
AI...
A previous study showed that ammonia oxidation by the Thaumarchaeota Nitrosopumilus maritimus (group 1.1a) was resistant
to concentrations of the C₈ 1-alkyne, octyne, which completely inhibits activity by ammonia-oxidizing bacteria. In this study, the
inhibitory effects of octyne and other C₂ to C₁₀ 1-alkynes were evaluated on the nitrite production...
Vibrio cholerae is autochthonous to various aquatic niches and is the etiological agent of the life-threatening diarrheal disease
cholera. The persistence of V. cholerae in natural habitats is a crucial factor in the epidemiology of cholera. In contrast to the
well-studied V. cholerae-chitin connection, scarce information is available about the...
“Mycobacterium avium subsp. hominissuis” is an opportunistic environmental pathogen that causes respiratory illness in immunocompromised patients, such as those with cystic fibrosis as well as other chronic respiratory diseases. Currently, there is no efficient approach to prevent or treat M. avium subsp. hominissuis infection in the lungs. During initial colonization...
Sensory hair cells convert mechanical motion into chemical signals. Otoferlin, a six-C2 domain transmembrane protein linked to deafness in humans, is hypothesized to play a
role in exocytosis at hair cell ribbon synapses. To date however, otoferlin has been
studied almost exclusively in mouse models, and no rescue experiments have...
Vibrio tubiashii is reported to be a bacterial pathogen of larval Eastern oysters (Crassostrea virginica) and Pacific oysters (Crassostrea
gigas) and has been associated with major hatchery crashes, causing shortages in seed oysters for commercial shellfish
producers. Another bacterium, Vibrio coralliilyticus, a well-known coral pathogen, has recently been shown to...
Next-generation DNA sequencing (NGS) approaches are rapidly surpassing Sanger sequencing for characterizing the diversity of
natural microbial communities. Despite this rapid transition, few comparisons exist between Sanger sequences and the generally
much shorter reads of NGS. Operational taxonomic units (OTUs) derived from full-length (Sanger sequencing) and pyrotag (454
sequencing of...
Two identical single-ascending-dose studies evaluated the safety and pharmacokinetics (PK) of AVI-6002 and AVI-6003, two experimental combinations of phosphorodiamidate morpholino oligomers with positive charges (PMOplus) that target viral mRNA encoding Ebola virus and Marburg virus proteins, respectively. Both AVI-6002 and AVI-6003 were found to suppress disease in virus-infected nonhuman primates...
Cyprinid herpesvirus 3 (CyHV-3), commonly known as koi herpesvirus (KHV), is a member of the Alloherpesviridae, and is a recently discovered emerging herpesvirus that is highly pathogenic for koi and common carp. Our previous study demonstrated that CyHV-3 becomes latent in peripheral white blood cells (WBC). In this study, CyHV-3...
The use of antibiotics is common in hospice care despite limited evidence that it improves symptoms or quality of life. Patients
receiving antibiotics upon discharge from a hospital may be more likely to continue use following transition to hospice care despite
a shift in the goals of care. We quantified...
In response to genotoxic stress, ATR and ATM kinases phosphorylate H2A in fungi and H2AX in animals on a C-terminal serine. The resulting modified histone, called γH2A, recruits chromatin-binding proteins that stabilize stalled replication forks or promote DNA double-strand-break repair. To identify genomic loci that might be prone to replication...
Inhibition of apoptotic death of macrophages by Mycobacterium tuberculosis represents an important mechanism of virulence that results in pathogen survival both in vitro and in vivo. To identify M. tuberculosis virulence determinants involved in the modulation of apoptosis, we previously screened a transposon bank of mutants in human macrophages, and...
Viruses were defined as one of the two principal types of organisms
in the biosphere, namely, as capsid-encoding organisms in
contrast to ribosome-encoding organisms, i.e., all cellular life
forms. Structurally similar, apparently homologous capsids are
present in a huge variety of icosahedral viruses that infect bacteria,
archaea, and eukaryotes. These...
Studies reporting on potentially toxic interactions between aqueous fullerene nanoparticles (nC₆₀) and
microorganisms have been contradictory. When known confounding factors were avoided, growth yields of
Saccharomyces cerevisiae and Escherichia coli cultured in the presence and absence of independently prepared
lots of underivatized nC₆₀ were found not to be significantly different.
Vibrio cholerae, an etiological agent of cholera, circulates between aquatic reservoirs and the human gastrointestinal tract. The
type II secretion (T2S) system plays a pivotal role in both stages of the lifestyle by exporting multiple proteins, including cholera
toxin. Here, we studied the kinetics of expression of genes encoding the...
Cryptococcus, a major cause of disseminated infections in immunocompromised patients, kills over 600,000 people per year
worldwide. Genes involved in the virulence of the meningitis-causing fungus are being characterized at an increasing rate, and to
date, at least 648 Cryptococcus gene names have been published. However, these data are scattered...
Successful host cell colonization by the Q fever pathogen, Coxiella burnetii, requires translocation of effector proteins into
the host cytosol by a Dot/Icm type 4B secretion system (T4BSS). In Legionella pneumophila, the two-component system (TCS)
PmrAB regulates the Dot/Icm T4BSS and several additional physiological processes associated with pathogenesis. Because PmrA...
Quantitative real-time PCR (qPCR) assays that target the human-associated HF183 bacterial cluster within members of the genus Bacteroides are among the most widely used methods for the characterization of human fecal pollution in ambient surface waters. In this study, we show that a current TaqMan HF183 qPCR assay (HF183/BFDrev) routinely...
Many bacteria possess cell density-dependent quorum-sensing (QS) systems that often regulate cooperative secretions involved
in host-microbe or microbe-microbe interactions. These secretions, or “public goods,” are frequently coregulated by stress and
starvation responses. Here we provide a physiological rationale for such regulatory complexity in the opportunistic pathogen
Pseudomonas aeruginosa. Using minimal-medium...
Engaging large numbers of undergraduates in authentic scientific discovery is desirable but difficult to achieve. We
have developed a general model in which faculty and teaching assistants from diverse academic institutions are trained to teach a
research course for first-year undergraduate students focused on bacteriophage discovery and genomics. The course...
We used metatranscriptomics to study the gene transcription patterns of microbial plankton (0.2 to 64 μm) at a mesohaline station
in the Chesapeake Bay under transitions from oxic to anoxic waters in spring and from anoxic to oxic waters in autumn.
Samples were collected from surface (i.e., above pycnocline) waters...
The Ti plasmid in Agrobacterium tumefaciens strain 15955 carries two alleles of traR that regulate conjugative transfer. The first
is a functional allele, called traR, that is transcriptionally induced by the opine octopine. The second, trlR, is a nonfunctional,
dominant-negative mutant located in an operon that is inducible by the...
Mycobacterium avium subsp. hominissuis is an opportunistic human pathogen that has been shown to form biofilm in vitro and
in vivo. Biofilm formation in vivo appears to be associated with infections in the respiratory tract of the host. The reasoning behind
how M. avium subsp. hominissuis biofilm is allowed to...
Nitrogen is one of the major nutrients limiting microbial productivity in the ocean, and as a result, most marine microorganisms
have evolved systems for responding to nitrogen stress. The highly abundant alphaproteobacterium “Candidatus
Pelagibacter ubique,” a cultured member of the order Pelagibacterales (SAR11), lacks the canonical GlnB, GlnD, GlnK, and...
CodY is known to regulate various virulence properties in several Gram-positive bacteria but has not yet been studied in the important histotoxic and intestinal pathogen Clostridium perfringens. The present study prepared an isogenic codY-null mutant in C. perfringens type D strain CN3718 by insertional mutagenesis using the Targetron system. Western...
Ammonia (NH₃)-oxidizing bacteria (AOB) and thaumarchaea (AOA) co-occupy most soils, yet no short-term growth-independent method exists to determine their relative contributions to nitrification in situ. Microbial monooxygenases differ in their vulnerability to inactivation by aliphatic n-alkynes, and we found that NH₃ oxidation by the marine thaumarchaeon Nitrosopumilus maritimus was unaffected...
Microbial adaptation to environmental conditions is a complex process, including acquisition of positive traits through horizontal gene transfer or the modification of existing genes through duplication and/or mutation. In this study, we examined the adaptation of a Pseudomonas fluorescens isolate (R124) from the nutrient-limited mineral environment of a silica cave...
The infection biology of Mycobacterium avium subsp. paratuberculosis has recently crystallized, with added details surrounding intestinal invasion. The involvement of pathogen-derived effector proteins such as the major membrane protein, oxidoreductase, and fibronectin attachment proteins have been uncovered. Mutations constructed in this pathogen have also shed light on genes needed for...
Enterococci are among the leading pathogens isolated in hospital-acquired infections. Current antimicrobial options for vancomycin-
resistant enterococci (VRE) are limited. Prior data suggest that daptomycin at>6 mg/kg of body weight/day may be used
to treat enterococcal infections. We retrospectively evaluated the effectiveness and safety of high-dose daptomycin (HD-daptomycin)
therapy (>6...
Clostridium difficile is an important nosocomial pathogen that has become a major cause of antibiotic-associated diarrhea.
There is a general consensus that C. difficile spores play an important role in C. difficile pathogenesis, contributing to infection,
persistence, and transmission. Evidence has demonstrated that C. difficile spores have an outermost layer,...
Conjugative plasmids are known to facilitate the acquisition and dispersal of genes contributing to the fitness of Pseudomonas spp. Here, we report the characterization of pA506, the 57-kb conjugative plasmid of Pseudomonas fluorescens A506, a plant epiphyte used in the United States for the biological control of fire blight disease...
Na⁺/H⁺ antiporters are ubiquitous membrane proteins that play a central role in the ion homeostasis of cells. In this study, we examined the possible role of Na⁺/H⁺ antiport in Yersinia pestis virulence and found that Y. pestis strains lacking the major Na⁺/H⁺ antiporters, NhaA and NhaB, are completely attenuated in...