bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Succinylation of Subtilin-Like Lantibiotics Are Strongly Influenced by Glucose and Transition State Regulator AbrB
Authors: Bochmann Sophie M. , Spieß Tobias , Kötter Peter , Entian Karl-Dieter 
Published: November 2014

ABSTRACT

Subtilin and the closely related entianin are class I lantibiotics produced by different subspecies of
Bacillus subtilis
. Both molecules are ribosomally synthesized peptide antibiotics with unusual ring structures. Subtilin-like lantibiotics develop strong antibiotic activities against various Gram-positive organisms with an efficiency similar to that of nisin from
Lactococcus lactis
. In contrast to nisin, subtilin-like lantibiotics partially undergo an additional posttranslational modification, where the N-terminal tryptophan residue becomes succinylated, resulting in drastically reduced antibiotic activities. A highly sensitive high-performance liquid chromatography (HPLC)-based quantification method enabled us to determine entianin and succinylated entianin (S-entianin) concentrations in the supernatant during growth. We show that entianin synthesis and the degree of succinylation drastically change with culture conditions. In particular, increasing glucose concentrations resulted in higher entianin amounts and lower proportions of S-entianin in Landy-based media. In contrast, no succinylation was observed in medium A with 10% glucose. Interestingly, glucose retarded the expression of entianin biosynthesis genes. Furthermore, deletion of the transition state regulator AbrB resulted in a 6-fold increased entianin production in medium A with 10% glucose. This shows that entianin biosynthesis in
B. subtilis
is strongly influenced by glucose, in addition to its regulation by the transition state regulator AbrB. Our results suggest that the mechanism underlying the succinylation of subtilin-like lantibiotics is enzymatically catalyzed and occurs in the extracellular space or at the cellular membrane.
Dehalococcoides mccartyi Strain DCMB5 Respires a Broad Spectrum of Chlorinated Aromatic Compounds
Authors: Pöritz Marlén , Schiffmann Christian L. , Hause Gerd , Heinemann Ulrike , Seifert Jana , Jehmlich Nico , von Bergen Martin , Nijenhuis Ivonne , Lechner Ute 
Published: November 2014

ABSTRACT

Polyhalogenated aromatic compounds are harmful environmental contaminants and tend to persist in anoxic soils and sediments.
Dehalococcoides mccartyi
strain DCMB5, a strain originating from dioxin-polluted river sediment, was examined for its capacity to dehalogenate diverse chloroaromatic compounds. Strain DCMB5 used hexachlorobenzenes, pentachlorobenzenes, all three tetrachlorobenzenes, and 1,2,3-trichlorobenzene as well as 1,2,3,4-tetra- and 1,2,4-trichlorodibenzo-
p
-dioxin as electron acceptors for organohalide respiration. In addition, 1,2,3-trichlorodibenzo-
p
-dioxin and 1,3-, 1,2-, and 1,4-dichlorodibenzo-
p
-dioxin were dechlorinated, the latter to the nonchlorinated congener with a remarkably short lag phase of 1 to 4 days following transfer. Strain DCMB5 also dechlorinated pentachlorophenol and almost all tetra- and trichlorophenols. Tetrachloroethene was dechlorinated to trichloroethene and served as an electron acceptor for growth. To relate selected dechlorination activities to the expression of specific reductive dehalogenase genes, the proteomes of 1,2,3-trichlorobenzene-, pentachlorobenzene-, and tetrachloroethene-dechlorinating cultures were analyzed. Dcmb_86, an ortholog of the chlorobenzene reductive dehalogenase CbrA, was the most abundant reductive dehalogenase during growth with each electron acceptor, suggesting its pivotal role in organohalide respiration of strain DCMB5. Dcmb_1041 was specifically induced, however, by both chlorobenzenes, whereas 3 putative reductive dehalogenases, Dcmb_1434, Dcmb_1339, and Dcmb_1383, were detected only in tetrachloroethene-grown cells. The proteomes also harbored a type IV pilus protein and the components for its assembly, disassembly, and secretion. In addition, transmission electron microscopy of DCMB5 revealed an irregular mode of cell division as well as the presence of pili, indicating that pilus formation is a feature of
D. mccartyi
during organohalide respiration.
Transcriptomics-Aided Dissection of the Intracellular and Extracellular Roles of Microcystin in Microcystis aeruginosa PCC 7806
Authors: Makower A. Katharina , Schuurmans J. Merijn , Groth Detlef , Zilliges Yvonne , Matthijs Hans C. P. , Dittmann Elke 
Published: November 2014

ABSTRACT

Recent studies have provided evidence for both intracellular and extracellular roles of the potent hepatotoxin microcystin (MC) in the bloom-forming cyanobacterium
Microcystis
. Here, we surveyed transcriptomes of the wild-type strain
M. aeruginosa
PCC 7806 and the microcystin-deficient Δ
mcyB
mutant under low light conditions with and without the addition of external MC of the LR variant (MC-LR). Transcriptomic data acquired by microarray and quantitative PCR revealed substantial differences in the relative expression of genes of the central intermediary metabolism, photosynthesis, and energy metabolism. In particular, the data provide evidence for a lower photosystem I (PSI)-to-photosystem II (PSII) ratio and a more pronounced carbon limitation in the microcystin-deficient mutant. Interestingly, only 6% of the transcriptional differences could be complemented by external microcystin-LR addition. This MC signaling effect was seen exclusively for genes of the secondary metabolism category. The orphan polyketide synthase gene cluster IPF38-51 was specifically downregulated in response to external MC-LR under low light. Our data suggest a hierarchical and light-dependent cross talk of secondary metabolites and support both an intracellular and an extracellular role of MC in
Microcystis
.
Genomic Diversity and Virulence Profiles of Historical Escherichia coli O157 Strains Isolated from Clinical and Environmental Sources
Authors: Rump Lydia V. , Gonzalez-Escalona Narjol , Ju Wenting , Wang Fei , Cao Guojie , Meng Sean , Meng Jianghong 
Published: November 2014

ABSTRACT

Escherichia coli
O157:H7 is, to date, the major
E. coli
serotype causing food-borne human disease worldwide. Strains of O157 with other H antigens also have been recovered. We analyzed a collection of historic O157 strains (
n
= 400) isolated in the late 1980s to early 1990s in the United States. Strains were predominantly serotype O157:H7 (55%), and various O157:non-H7 (41%) serotypes were not previously reported regarding their pathogenic potential. Although lacking Shiga toxin (
stx
) and
eae
genes, serotypes O157:H1, O157:H2, O157:H11, O157:H42, and O157:H43 carried several virulence factors (
iha
,
terD
, and
hlyA
) also found in virulent serotype
E. coli
O157:H7. Pulsed-field gel electrophoresis (PFGE) showed the O157 serogroup was diverse, with strains with the same H type clustering together closely. Among non-H7 isolates, serotype O157:H43 was highly prevalent (65%) and carried important enterohemorrhagic
E. coli
(EHEC) virulence markers (
iha
,
terD
,
hlyA
, and
espP
). Isolates from two particular H types, H2 and H11, among the most commonly found non-O157 EHEC serotypes (O26:H11, O111:H11, O103:H2/H11, and O45:H2), unexpectedly clustered more closely with O157:H7 than other H types and carried several virulence genes. This suggests an early divergence of the O157 serogroup to clades with different pathogenic potentials. The appearance of important EHEC virulence markers in closely related H types suggests their virulence potential and suggests further monitoring of those serotypes not implicated in severe illness thus far.
Application of Chitosan Microparticles for Reduction of Vibrio Species in Seawater and Live Oysters (Crassostrea virginica)
Authors: Fang Lei , Wolmarans Bernhard , Kang Minyoung , Jeong Kwang C. , Wright Anita C. 
Published: November 2014

ABSTRACT

Human
Vibrio
infections associated with consumption of raw shellfish greatly impact the seafood industry.
Vibrio cholerae
-related disease is occasionally attributed to seafood, but
V. vulnificus
and
V. parahaemolyticu
s are the primary targets of postharvest processing (PHP) efforts in the United States, as they pose the greatest threat to the industry. Most successful PHP treatments for
Vibrio
reduction also kill the molluscs and are not suitable for the lucrative half-shell market, while nonlethal practices are generally less effective. Therefore, novel intervention strategies for
Vibrio
reduction are needed for live oyster products. Chitosan is a bioactive derivative of chitin that is generally recognized as safe as a food additive by the FDA, and chitosan microparticles (CMs) were investigated in the present study as a potential PHP treatment for live oyster applications. Treatment of broth cultures with 0.5% (wt/vol) CMs resulted in growth cessation of
V. cholerae
,
V. vulnificus
, and
V. parahaemolyticus
, reducing culturable levels to nondetectable amounts after 3 h in three independent experiments. Furthermore, a similar treatment in artificial seawater at 4, 25, and 37°C reduced
V. vulnificus
levels by ca. 7 log CFU/ml after 24 h of exposure, but 48 h of exposure and elevated temperature were required to achieve similar results for
V. parahaemolyticus
and
V. cholerae
. Live oysters that either were artificially inoculated or contained natural populations of
V. vulnificus
and
V. parahaemolyticus
showed significant and consistent reductions following CM treatment (5%) compared to the amounts in the untreated controls. Thus, the results strongly support the promising potential for the application of CMs as a PHP treatment to reduce
Vibrio
spp. in intact live oysters.
Engineering Neurospora crassa for Improved Cellobiose and Cellobionate Production
Authors: Hildebrand Amanda , Szewczyk Edyta , Lin Hui , Kasuga Takao , Fan Zhiliang 
Published: November 2014

ABSTRACT

We report engineering
Neurospora crassa
to improve the yield of cellobiose and cellobionate from cellulose. A previously engineered strain of
N. crassa
(F5) with six of seven β-glucosidase (
bgl
) genes knocked out was shown to produce cellobiose and cellobionate directly from cellulose without the addition of exogenous cellulases. In this study, the F5 strain was further modified to improve the yield of cellobiose and cellobionate from cellulose by increasing cellulase production and decreasing product consumption. The effects of two catabolite repression genes,
cre-1
and
ace-1
, on cellulase production were investigated. The F5 Δ
ace-1
mutant showed no improvement over the wild type. The F5 Δ
cre-1
and F5 Δ
ace-1
Δ
cre-1
strains showed improved cellobiose dehydrogenase and exoglucanase expression. However, this improvement in cellulase expression did not lead to an improvement in cellobiose or cellobionate production. The cellobionate phosphorylase gene (
ndvB
) was deleted from the genome of F5 Δ
ace-1
Δ
cre-1
to prevent the consumption of cellobiose and cellobionate. Despite a slightly reduced hydrolysis rate, the F5 Δ
ace-1
Δ
cre-1
Δ
ndvB
strain converted 75% of the cellulose consumed to the desired products, cellobiose and cellobionate, compared to 18% converted by the strain F5 Δ
ace-1
Δ
cre-1
.
Aerosolization of Respirable Droplets from a Domestic Spa Pool and the Use of MS-2 Coliphage and Pseudomonas aeruginosa as Markers for Legionella pneumophila
Authors: Moore Ginny , Hewitt Matthew , Stevenson David , Walker Jimmy T. , Bennett Allan M. 
Published: November 2014

ABSTRACT

Legionnaires' disease can result when droplets or aerosols containing legionella bacteria are inhaled and deposited in the lungs. A number of outbreaks have been associated with the use of a spa pool where aeration, a high water temperature, and a large and variable organic load make disinfectant levels difficult to maintain. Spa pool ownership is increasing, and the aim of this study, using two surrogate organisms (MS-2 coliphage and
Pseudomonas aeruginosa
[a natural contaminant]), was to assess the potential risk to domestic users when disinfection fails. A representative “entry level” domestic spa pool was installed in an outdoor courtyard. The manufacturer's instructions for spa pool maintenance were not followed. A cyclone sampler was used to sample the aerosols released from the spa pool with and without activation of the air injection system. Samples were taken at increasing heights and distances from the pool. An aerodynamic particle sizer was used to measure the water droplet size distribution at each sample point. When the air injection system was inactivated, neither surrogate organism was recovered from the air. On activation of the air injection system, the mean mass of droplets within the respirable range (10 cm above the water line) was 36.8 μg cm
−3
. This corresponded to a mean air concentration of
P. aeruginosa
of 350 CFU m
−3
. From extrapolation from animal data, the estimated risk of infection from aerosols contaminated with similar concentrations of
Legionella pneumophila
was 0.76 (males) and 0.65 (females). At 1 m above and/or beyond the pool, the mean aerosol mass decreased to 0.04 μg cm
−3
and corresponded to a 100-fold reduction in mean microbial air concentration. The estimated risk of infection at this distance was negligible.
Glutamate Decarboxylase-Dependent Acid Resistance in Brucella spp.: Distribution and Contribution to Fitness under Extremely Acidic Conditions
Authors: Damiano Maria Alessandra , Bastianelli Daniela , Al Dahouk Sascha , Köhler Stephan , Cloeckaert Axel , De Biase Daniela , Occhialini Alessandra 
Published: November 2014

ABSTRACT

Brucella
is an expanding genus of major zoonotic pathogens, including at least 10 genetically very close species occupying a wide range of niches from soil to wildlife, livestock, and humans. Recently, we have shown that in the new species
Brucella microti
, the glutamate decarboxylase (Gad)-dependent system (GAD system) contributes to survival at a pH of 2.5 and also to infection in mice by the oral route. In order to study the functionality of the GAD system in the genus
Brucella
, 47 isolates, representative of all known species and strains of this genus, and 16 strains of the closest neighbor genus,
Ochrobactrum
, were studied using microbiological, biochemical, and genetic approaches. In agreement with the genome sequences, the GAD system of classical species was not functional, unlike that of most strains of
Brucella ceti
,
Brucella pinnipedialis
, and newly described species (
B. microti
,
Brucella inopinata
BO1,
B. inopinata
-like BO2, and
Brucella
sp. isolated from bullfrogs). In the presence of glutamate, these species were more acid resistant
in vitro
than classical terrestrial brucellae. Expression in
trans
of the
gad
locus from representative
Brucella
species in the
Escherichia coli
MG1655 mutant strain lacking the GAD system restored the acid-resistant phenotype. The highly conserved GAD system of the newly described or atypical
Brucella
species may play an important role in their adaptation to acidic external and host environments. Furthermore, the GAD phenotype was shown to be a useful diagnostic tool to distinguish these latter
Brucella
strains from
Ochrobactrum
and from classical terrestrial pathogenic
Brucella
species, which are GAD negative.
Entericidin Is Required for a Probiotic Treatment (Enterobacter sp. Strain C6-6) To Protect Trout from Cold-Water Disease Challenge
Authors: Schubiger Carla B. , Orfe Lisa H. , Sudheesh Ponnerassery S. , Cain Kenneth D. , Shah Devendra H. , Call Douglas R. 
Published: November 2014

ABSTRACT

Flavobacterium psychrophilum
causes bacterial cold-water disease in multiple fish species, including salmonids. An autochthonous
Enterobacter
strain (C6-6) inhibits the
in vitro
growth of
F. psychrophilum
, and when ingested as a putative probiotic, it provides protection against injection challenge with
F. psychrophilum
in rainbow trout. In this study, low-molecular-mass (≤3 kDa) fractions from both
Enterobacter
C6-6 and
Escherichia coli
K-12 culture supernatants inhibited the growth of
F. psychrophilum
. The ≤3-kDa fraction from
Enterobacter
C6-6 was analyzed by SDS-PAGE, and subsequent tandem mass spectroscopy identified EcnB, which is a small membrane lipoprotein that is a putative pore-forming toxin. Agar plate diffusion assays demonstrated that
ecnAB
knockout strains of both
Enterobacter
C6-6 and
E. coli
K-12 no longer inhibited
F. psychrophilum
(
P
< 0.001), while
ecnAB
-complemented knockout strains recovered the inhibitory phenotype (
P
< 0.001). In fish experiments, the engineered strains (C6-6 Δ
ecnAB
and C6-6 Δ
ecnAB
<pET101::
ecnAB
>) and the wild-type strain (C6-6) were added to the fish diet every day for 38 days. On day 11, the fish were challenged by injection with a virulent strain of
F. psychrophilum
(CSF 259-93). Fish that were fed C6-6 had significantly longer survival than fish fed the
ecnAB
knockout strain (
P
< 0.0001), while fish fed the complemented knockout strain recovered the probiotic phenotype (
P
= 0.61). This entericidin is responsible for the probiotic activity of
Enterobacter
C6-6, and it may present new opportunities for therapeutic and prophylactic treatments against similarly susceptible pathogens.
Exposure to Synthetic Gray Water Inhibits Amoeba Encystation and Alters Expression of Legionella pneumophila Virulence Genes
Authors: Buse Helen Y. , Lu Jingrang , Ashbolt Nicholas J. 
Published: November 2014

ABSTRACT

Water conservation efforts have focused on gray water (GW) usage, especially for applications that do not require potable water quality. However, there is a need to better understand environmental pathogens and their free-living amoeba (FLA) hosts within GW, given their growth potential in stored gray water. Using synthetic gray water (sGW) we examined three strains of the water-based pathogen
Legionella pneumophila
and its FLA hosts
Acanthamoeba polyphaga
,
A. castellanii
, and
Vermamoeba vermiformis
. Exposure to sGW for 72 h resulted in significant inhibition (
P
< 0.0001) of amoebal encystation versus control-treated cells, with the following percentages of cysts in sGW versus controls:
A. polyphaga
(0.6 versus 6%),
A. castellanii
(2 versus 62%), and
V. vermiformis
(1 versus 92%), suggesting sGW induced maintenance of the actively feeding trophozoite form. During sGW exposure,
L. pneumophila
culturability decreased as early as 5 h (1.3 to 2.9 log
10
CFU,
P
< 0.001) compared to controls (Δ0 to 0.1 log
10
CFU) with flow cytometric analysis revealing immediate changes in membrane permeability. Furthermore, reverse transcription-quantitative PCR was performed on total RNA isolated from
L. pneumophila
cells at 0 to 48 h after sGW incubation, and genes associated with virulence (
gacA
,
lirR
,
csrA
,
pla
, and
sidF
), the type IV secretion system (
lvrB
and
lvrE
), and metabolism (
ccmF
and
lolA
) were all shown to be differentially expressed. These results suggest that conditions within GW may promote interactions between water-based pathogens and FLA hosts, through amoebal encystment inhibition and alteration of bacterial gene expression, thus warranting further exploration into FLA and
L. pneumophila
behavior in GW systems.
Both the Charged Linker Region and ATPase Domain of Hsp90 Are Essential for Rad51-Dependent DNA Repair
Authors: Suhane Tanvi , Laskar Shyamasree , Advani Siddheshwari , Roy Nabamita , Varunan Shalu , Bhattacharyya Dibyendu , Bhattacharyya Sunanda , Bhattacharyya Mrinal Kanti 
Published: November 2014

ABSTRACT

The inhibition of Hsp90 in cancerous cells has been correlated with the reduction in double-strand break (DSB repair) activity. However, the precise effect of Hsp90 on the DSB repair pathway in normal cells has remained enigmatic. Our results show that the Hsp82 chaperone, the ortholog of mammalian Hsp90, is indispensable for homologous-recombination (HR)-mediated DNA repair in the budding yeast
Saccharomyces cerevisiae
. A considerable reduction in cell viability is observed in an Hsp82-inactivated mutant upon methyl methanesulfonate (MMS) treatment as well as upon UV treatment. The loss of Hsp82 function results in a dramatic decrease in gene-targeting efficiency and a marked decrease in the endogenous levels of the key recombination proteins Rad51 and Rad52 without any notable change in the levels of
RAD51
or
RAD52
transcripts. Our results establish Rad51 as a client of Hsp82, since they interact physically
in vivo
, and also show that when Hsp82 is inhibited by 17-AAG, Rad51 undergoes proteasomal degradation. By analyzing a number of point mutants with mutations in different domains of Hsp82, we observe a strong association between the sensitivity of an ATPase mutant of Hsp82 to DNA damage and the decreases in the amounts of Rad51 and Rad52 proteins. The most significant observations include the dramatic abrogation of HR activity and the marked decrease in Rad51 focus formation in the charged linker deletion mutant of Hsp82 upon MMS treatment. The charged linker region of Hsp82 is evolutionarily conserved in all eukaryotes, but until now, no biological significance has been assigned to it. Our findings elucidate the importance of this region in DNA repair for the first time.
The Hsp90 Cochaperones Cpr6, Cpr7, and Cns1 Interact with the Intact Ribosome
Authors: Tenge Victoria R. , Zuehlke Abbey D. , Shrestha Neelima , Johnson Jill L. 
Published: November 2014

ABSTRACT

The abundant molecular chaperone Hsp90 is essential for the folding and stabilization of hundreds of distinct client proteins. Hsp90 is assisted by multiple cochaperones that modulate Hsp90's ATPase activity and/or promote client interaction, but the
in vivo
functions of many of these cochaperones are largely unknown. We found that Cpr6, Cpr7, and Cns1 interact with the intact ribosome and that
Saccharomyces cerevisiae
lacking
CPR7
or containing mutations in
CNS1
exhibited sensitivity to the translation inhibitor hygromycin. Cpr6 contains a peptidyl-prolyl isomerase (PPIase) domain and a tetratricopeptide repeat (TPR) domain flanked by charged regions. Truncation or alteration of basic residues near the carboxy terminus of Cpr6 disrupted ribosome interaction. Cns1 contains an amino-terminal TPR domain and a poorly characterized carboxy-terminal domain. The isolated carboxy-terminal domain was able to interact with the ribosome. Although loss of
CPR6
does not cause noticeable growth defects, overexpression of
CPR6
results in enhanced growth defects in cells expressing the temperature-sensitive
cns1-G90D
mutation (the G-to-D change at position 90 encoded by
cns1
). Cpr6 mutants that exhibit reduced ribosome interaction failed to cause growth defects, indicating that ribosome interaction is required for
in vivo
functions of Cpr6. Together, these results represent a novel link between the Hsp90 molecular-chaperone machine and protein synthesis.