bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bacillus thuringiensisBel Protein Enhances the Toxicity of Cry1Ac Protein toHelicoverpa armigeraLarvae by Degrading Insect Intestinal Mucin
Authors: Fang Shangling , Wang Li , Guo Wei , Zhang Xia , Peng Donghai , Luo Chunping , Yu Ziniu , Sun Ming 
Published: June 2009

ABSTRACTBacillus thuringiensishas been used as a bioinsecticide to control agricultural insects.Bacillus cereusgroup genomes were found to have aBacillusenhancin-like (bel) gene, encoding a peptide with 20 to 30% identity to viral enhancin protein, which can enhance viral infection by degradation of the peritrophic matrix (PM) of the insect midgut. In this study, thebelgene was found to have an activity similar to that of the viral enhancin gene. Abelknockout mutant was constructed by using a plasmid-freeB. thuringiensisderivative, BMB171. The 50% lethal concentrations of this mutant plus thecry1Acinsecticidal protein gene were about 5.8-fold higher than those of the BMB171 strain. When purified Bel was mixed with the Cry1Ac protein and fed toHelicoverpa armigeralarvae, 3 μg/ml Cry1Ac alone induced 34.2% mortality. Meanwhile, the mortality rate rose to 74.4% when the same amount of Cry1Ac was mixed with 0.8 μg/ml of Bel. Microscopic observation showed a significant disruption detected on the midgut PM ofH. armigeralarvae after they were fed Bel. In vitro degradation assays showed that Bel digested the intestinal mucin (IIM) ofTrichoplusia niandH. armigeralarvae to various degrading products, similar to findings for viral enhancin. These results imply Bel toxicity enhancement depends on the destruction of midgut PM and IIM, similar to the case with viral enhancin. This discovery showed that Bel has the potential to enhance insecticidal activity ofB. thuringiensis-based biopesticides and transgenic crops.
Kinetic Characterization of OmcA and MtrC, Terminal Reductases Involved in Respiratory Electron Transfer for Dissimilatory Iron Reduction in
Shewanella oneidensis
MR-1
Authors: Ross Daniel E. , Brantley Susan L. , Tien Ming 
Published: June 2009

ABSTRACT

We have used scaling kinetics and the concept of kinetic competence to elucidate the role of hemeproteins OmcA and MtrC in iron reduction by
Shewanella oneidensis
MR-1. Second-order rate constants for OmcA and MtrC were determined by single-turnover experiments. For soluble iron species, a stopped-flow apparatus was used, and for the less reactive iron oxide goethite, a conventional spectrophotometer was used to measure rates. Steady-state experiments were performed to obtain molecular rate constants by quantifying the OmcA and MtrC contents of membrane fractions and whole cells by Western blot analysis. For reduction of soluble iron, rates determined from transient-state experiments were able to account for rates obtained from steady-state experiments. However, this was not true with goethite; rate constants determined from transient-state experiments were 100 to 1,000 times slower than those calculated from steady-state experiments with membrane fractions and whole cells. In contrast, addition of flavins to the goethite experiments resulted in rates that were consistent with both transient- and steady-state experiments. Kinetic simulations of steady-state results with kinetic constants obtained from transient-state experiments supported flavin involvement. Therefore, we show for the first time that OmcA and MtrC are kinetically competent to account for catalysis of soluble iron reduction in whole
Shewanella
cells but are not responsible for electron transfer via direct contact alone with insoluble iron-containing minerals. This work supports the hypothesis that electron shuttles are important participants in the reduction of solid Fe phases by this organism.
Novel Denitrifying Bacterium
Ochrobactrum anthropi
YD50.2 Tolerates High Levels of Reactive Nitrogen Oxides
Authors: Doi Yuki , Takaya Naoki , Takizawa Noboru 
Published: June 2009

ABSTRACT

Most studies of bacterial denitrification have used nitrate (NO
3
−
) as the first electron acceptor, whereas relatively less is understood about nitrite (NO
2
−
) denitrification. We isolated novel bacteria that proliferated in the presence of high levels of NO
2
−
(72 mM). Strain YD50.2, among several isolates, was taxonomically positioned within the α subclass of
Proteobacteria
and identified as
Ochrobactrum anthropi
YD50.2. This strain denitrified NO
2
−
, as well as NO
3
−
. The gene clusters for denitrification (
nar
,
nir
,
nor
, and
nos
) were cloned from
O. anthropi
YD50.2, in which the
nir
and
nor
operons were linked. We confirmed that
nirK
in the
nir
-
nor
operon produced a functional NO
2
−
reductase containing copper that was involved in bacterial NO
2
−
reduction. The strain denitrified up to 40 mM NO
2
−
to dinitrogen under anaerobic conditions in which other denitrifiers or NO
3
−
reducers such as
Pseudomonas aeruginosa
and
Ralstonia eutropha
and nitrate-respiring
Escherichia coli
neither proliferated nor reduced NO
2
−
. Under nondenitrifying aerobic conditions,
O. anthropi
YD50.2 and its type strain ATCC 49188
T
proliferated even in the presence of higher levels of NO
2
−
(100 mM), and both were considerably more resistant to acidic NO
2
−
than were the other strains noted above. These results indicated that
O. anthropi
YD50.2 is a novel denitrifier that has evolved reactive nitrogen oxide tolerance mechanisms.
Roles of Small, Acid-Soluble Spore Proteins and Core Water Content in Survival of
Bacillus subtilis
Spores Exposed to Environmental Solar UV Radiation
Authors: Moeller Ralf , Setlow Peter , Reitz Günther , Nicholson Wayne L. 
Published: June 2009

ABSTRACT

Spores of
Bacillus subtilis
contain a number of small, acid-soluble spore proteins (SASP) which comprise up to 20% of total spore core protein. The multiple α/β-type SASP have been shown to confer resistance to UV radiation, heat, peroxides, and other sporicidal treatments. In this study, SASP-defective mutants of
B. subtilis
and spores deficient in
dacB
, a mutation leading to an increased core water content, were used to study the relative contributions of SASP and increased core water content to spore resistance to germicidal 254-nm and simulated environmental UV exposure (280 to 400 nm, 290 to 400 nm, and 320 to 400 nm). Spores of strains carrying mutations in
sspA
,
sspB
, and both
sspA
and
sspB
(lacking the major SASP-α and/or SASP-β) were significantly more sensitive to 254-nm and all polychromatic UV exposures, whereas the UV resistance of spores of the
sspE
strain (lacking SASP-γ) was essentially identical to that of the wild type. Spores of the
dacB
-defective strain were as resistant to 254-nm UV-C radiation as wild-type spores. However, spores of the
dacB
strain were significantly more sensitive than wild-type spores to environmental UV treatments of >280 nm. Air-dried spores of the
dacB
mutant strain had a significantly higher water content than air-dried wild-type spores. Our results indicate that α/β-type SASP and decreased spore core water content play an essential role in spore resistance to environmentally relevant UV wavelengths whereas SASP-γ does not.
Genetic Diversity and Multihost Pathogenicity of Clinical and Environmental Strains ofBurkholderia cenocepacia
Authors: Springman A. Cody , Jacobs Janette L. , Somvanshi Vishal S. , Sundin George W. , Mulks Martha H. , Whittam Thomas S. , Viswanathan Poorna , Gray R. Lucas , LiPuma John J. , Ciche Todd A. 
Published: June 2009

ABSTRACTA collection of 54 clinical and agricultural isolates ofBurkholderia cenocepaciawas analyzed for genetic relatedness by using multilocus sequence typing (MLST), pathogenicity by using onion and nematode infection models, antifungal activity, and the distribution of three marker genes associated with virulence. The majority of clinical isolates were obtained from cystic fibrosis (CF) patients in Michigan, and the agricultural isolates were predominantly from Michigan onion fields. MLST analysis resolved 23 distinct sequence types (STs), 11 of which were novel. Twenty-six of 27 clinical isolates from Michigan were genotyped as ST-40, previously identified as the MidwestB. cenocepacialineage. In contrast, the 12 agricultural isolates represented eight STs, including ST-122, that were identical to clinical isolates of the PHDC lineage. In general, pathogenicity to onions and the presence of thepehAendopolygalacturonase gene were detected only in one cluster of related strains consisting of agricultural isolates and the PHDC lineage. Surprisingly, these strains were highly pathogenic in the nematodeCaenorhabditis elegansinfection model, killing nematodes faster than the CF pathogenPseudomonas aeruginosaPA14 on slow-kill medium. The other strains displayed a wide range of pathogenicity toC. elegans, notably the Midwest clonal lineage which displayed high, moderate, and low virulence. Most strains displayed moderate antifungal activity, although strains with high and low activities were also detected. We conclude that pathogenicity to multiple hosts may be a key factor contributing to the potential ofB. cenocepaciato opportunistically infect humans both by increasing the prevalence of the organism in the environment, thereby increasing exposure to vulnerable hosts, and by the selection of virulence factors that function in multiple hosts.
Identification of Three Alcohol Dehydrogenase Genes Involved in the Stereospecific Catabolism of Arylglycerol-β-Aryl Ether by
Sphingobium
sp. Strain SYK-6
Authors: Sato Yusuke , Moriuchi Hideki , Hishiyama Shojiro , Otsuka Yuichiro , Oshima Kenji , Kasai Daisuke , Nakamura Masaya , Ohara Seiji , Katayama Yoshihiro , Fukuda Masao , Masai Eiji 
Published: June 2009

ABSTRACT

Degradation of arylglycerol-β-aryl ether is the most important process in bacterial lignin catabolism.
Sphingobium
sp. strain SYK-6 degrades guaiacylglycerol-β-guaiacyl ether (GGE) to α-(2-methoxyphenoxy)-β-hydroxypropiovanillone (MPHPV), and then the ether linkage of MPHPV is cleaved to generate α-glutathionyl-β-hydroxypropiovanillone (GS-HPV) and guaiacol. We have characterized three enantioselective glutathione
S
-transferase genes, including two genes that are involved in the ether cleavage of two enantiomers of MPHPV and one gene that is involved in the elimination of glutathione from a GS-HPV enantiomer. However, the first step in the degradation of four different GGE stereoisomers has not been characterized. In this study, three alcohol dehydrogenase genes,
ligL
,
ligN
, and
ligO
, which conferred GGE transformation activity in
Escherichia coli
, were isolated from SYK-6 and characterized, in addition to the previously cloned
ligD
gene. The levels of amino acid sequence identity of the four GGE dehydrogenases, which belong to the short-chain dehydrogenase/reductase family, ranged from 32% to 39%. Each gene was expressed in
E. coli
, and the stereospecificities of the gene products with the four GGE stereoisomers were determined by using chiral high-performance liquid chromatography with recently synthesized authentic enantiopure GGE stereoisomers. LigD and LigO converted (α
R
,β
S
)-GGE and (α
R
,β
R
)-GGE into (β
S
)-MPHPV and (β
R
)-MPHPV, respectively, while LigL and LigN transformed (α
S
,β
R
)-GGE and (α
S
,β
S
)-GGE to (β
R
)-MPHPV and (β
S
)-MPHPV, respectively. Disruption of the genes indicated that
ligD
is essential for the degradation of (α
R
,β
S
)-GGE and (α
R
,β
R
)-GGE and that both
ligL
and
ligN
contribute to the degradation of the two other GGE stereoisomers.
Anaerobic Respiration of Elemental Sulfur and Thiosulfate by
Shewanella oneidensis
MR-1 Requires
psrA
, a Homolog of the
phsA
Gene of
Salmonella enterica
Serovar Typhimurium LT2
Authors: Burns Justin L. , DiChristina Thomas J. 
Published: June 2009

ABSTRACT

Shewanella oneidensis
MR-1, a facultatively anaerobic gammaproteobacterium, respires a variety of anaerobic terminal electron acceptors, including the inorganic sulfur compounds sulfite (SO
3
2−
), thiosulfate (S
2
O
3
2−
), tetrathionate (S
4
O
6
2−
), and elemental sulfur (S
0
). The molecular mechanism of anaerobic respiration of inorganic sulfur compounds by
S. oneidensis
, however, is poorly understood. In the present study, we identified a three-gene cluster in the
S. oneidensis
genome whose translated products displayed 59 to 73% amino acid similarity to the products of
phsABC
, a gene cluster required for S
0
and S
2
O
3
2−
respiration by
Salmonella enterica
serovar Typhimurium LT2. Homologs of
phsA
(annotated as
psrA
) were identified in the genomes of
Shewanella
strains that reduce S
0
and S
2
O
3
2−
yet were missing from the genomes of
Shewanella
strains unable to reduce these electron acceptors. A new suicide vector was constructed and used to generate a markerless, in-frame deletion of
psrA
, the gene encoding the putative thiosulfate reductase. The
psrA
deletion mutant (PSRA1) retained expression of downstream genes
psrB
and
psrC
but was unable to respire S
0
or S
2
O
3
2−
as the terminal electron acceptor. Based on these results, we postulate that PsrA functions as the main subunit of the
S. oneidensis
S
2
O
3
2−
terminal reductase whose end products (sulfide [HS
−
] or SO
3
2−
) participate in an intraspecies sulfur cycle that drives S
0
respiration.
Controlled Gene Expression in the Plant Pathogen
Cryphonectria parasitica
by Use of a Copper-Responsive Element
Authors: Willyerd Karyn L. , Kemp Amanda M. , Dawe Angus L. 
Published: June 2009

ABSTRACT

We have developed a tool for controlled expression of heterologous or ectopic genes in the chestnut pathogen
Cryphonectria parasitica
using the promoter region from a putative copper-regulated transporter gene. In addition, we have found that expression control via this system is not affected by the virulence-attenuating hypovirus CHV1-EP713.
Genetic Determinants of Symptoms on Viral DNA Satellites
Authors: Ding Chenjun , Qing Ling , Li Zhenghe , Liu Yi , Qian Yajuan , Zhou Xueping 
Published: June 2009

ABSTRACT

Begomovirus-DNA-β disease complexes induce different symptom phenotypes in their hosts. To investigate the genetic determinants of the phenotypic differences,
Nicotiana
spp. and tomato plants were inoculated with infectious clones of
Tobacco curly shoot virus
(TbCSV)/TbCSV DNA-β (TbCSB) and
Tomato yellow leaf curl China virus
(TYLCCNV)/TYLCCNV DNA-β (TYLCCNB) pseudorecombinants and showed that TYLCCNB induced characteristic vein-thickening and enation symptoms, while TbCSB only slightly exacerbated the leaf-curling symptoms, regardless of the helper virus being used. The roles of DNA-β-encoded βC1 and a 430-nucleotide fragment containing the A-rich region and the putative βC1 promoter region of the
βC1
gene (referred to as AP) in symptom development were further investigated by constructing hybrid satellites in which the βC1 coding region or AP was exchanged between the two satellite molecules. A TYLCCNB hybrid with TbCSB βC1 lost the ability to elicit the vein-thickening and enation phenotypes. TbCSB hybrids containing the TYLCCNB βC1 or AP fragment failed to induce the characteristic vein thickening and enations. A TYLCCNB hybrid having the TbCSB AP fragment produced the enations, but the number of enations was less and their sizes were reduced. Differently from the phloem-specific pattern of the TYLCCNB promoter, a full-length fragment upstream of the TbCSB
βC1
gene confers a constitutive β-glucuronidase expression pattern in transgenic tobacco plants. The above results indicate that the DNA-β-encoded βC1 protein is the symptom determinant, but the promoter of the
βC1
gene has influence on symptom production.
Role of P450 Monooxygenases in the Degradation of the Endocrine-Disrupting Chemical Nonylphenol by the White Rot Fungus
Phanerochaete chrysosporium
Authors: Subramanian Venkataramanan , Yadav Jagjit S. 
Published: June 2009

ABSTRACT

The white rot fungus
Phanerochaete chrysosporium
extensively degraded the endocrine disruptor chemical nonylphenol (NP; 100% of 100 ppm) in both nutrient-limited cultures and nutrient-sufficient cultures. The P450 enzyme inhibitor piperonyl butoxide caused significant inhibition (∼75%) of the degradation activity in nutrient-rich malt extract (ME) cultures but no inhibition in defined low-nitrogen (LN) cultures, indicating an essential role of P450 monooxygenase(s) in NP degradation under nutrient-rich conditions. A genome-wide analysis using our custom-designed P450 microarray revealed significant induction of multiple P450 monooxygenase genes by NP: 18 genes were induced (2- to 195-fold) under nutrient-rich conditions, 17 genes were induced (2- to 6-fold) in LN cultures, and 3 were induced under both nutrient-rich and LN conditions. The P450 genes Pff 311b (corresponding to protein identification number [ID] 5852) and Pff 4a (protein ID 5001) showed extraordinarily high levels of induction (195- and 167-fold, respectively) in ME cultures. The P450 oxidoreductase (
POR
), glutathione
S
-transferase (
gst
), and cellulose metabolism genes were also induced in ME cultures. In contrast, certain metabolic genes, such as five of the peroxidase genes, showed partial downregulation by NP. This study provides the first evidence for the involvement of P450 enzymes in NP degradation by a white rot fungus and the first genome-wide identification of specific P450 genes responsive to an environmentally significant toxicant.
Innate Immune Defenses Induced by CpG Do Not Promote Vaccine-Induced Protection against Foot-and-Mouth Disease Virus in Pigs
Authors: Alves M. P. , Guzylack-Piriou L. , Juillard V. , Audonnet J.-C. , Doel T. , Dawson H. , Golde W. T. , Gerber H. , Peduto N. , McCullough K. C. , Summerfield A. 
Published: June 2009

ABSTRACTEmergency vaccination as part of the control strategies against foot-and-mouth disease virus (FMDV) has the potential to limit virus spread and reduce large-scale culling. To reduce the time between vaccination and the onset of immunity, immunostimulatory CpG was tested for its capacity to promote early protection against FMDV challenge in pigs. To this end, CpG 2142, an efficient inducer of alpha interferon, was injected intramuscularly. Increased transcription of Mx1, OAS, and IRF-7 was identified as a sensitive measurement of CpG-induced innate immunity, with increased levels detectable to at least 4 days after injection of CpG formulated with Emulsigen. Despite this, CpG combined with an FMD vaccine did not promote protection. Pigs vaccinated 2 days before challenge had disease development, which was at least as acute as that of unvaccinated controls. All pigs vaccinated 7 days before challenge were protected without a noticeable effect of CpG. In summary, our results demonstrate the caution required when translating findings from mouse models to natural hosts of FMDV.
Production of Extracellular Polysaccharides by
CAP
Mutants of
Cryptococcus neoformans
Authors: Grijpstra Jan , Gerwig Gerrit J. , Wösten Han , Kamerling Johannis P. , de Cock Hans 
Published: June 2009

ABSTRACT

The human pathogen
Cryptococcus neoformans
causes meningoencephalitis. The polysaccharide capsule is one of the main virulence factors and consists of two distinct polysaccharides, glucuronoxylomannan (GXM) and galactoxylomannan (GalXM). How capsular polysaccharides are synthesized, transported, and assembled is largely unknown. Previously, it was shown that mutations in the
CAP10
,
CAP59
,
CAP60
, and
CAP64
genes result in an acapsular phenotype. Here, it is shown that these acapsular mutants do secrete GalXM and GXM-like polymers. GXM and GalXM antibodies specifically reacted with whole cells and the growth medium of the wild type and
CAP
mutants, indicating that the capsule polysaccharides adhere to the cell wall and are shed into the environment. These polysaccharides were purified from the medium, either with or without anion-exchange chromatography. Monosaccharide analysis of polysaccharide fractions by gas-liquid chromatography/mass spectrometry showed that wild-type cells secrete both GalXM and GXM. The
CAP
mutants, on the other hand, were shown to secrete GalXM and GXM-like polymers. Notably, the GalXM polymers were shown to contain glucuronic acid. One-dimensional
1
H nuclear magnetic resonance confirmed that the
CAP
mutants secrete GalXM and also showed the presence of O-acetylated polymers. This is the first time it is shown that
CAP
mutants secrete GXM-like polymers in addition to GalXM. The small amount of this GXM-like polymer, 1 to 5% of the total amount of secreted polysaccharides, may explain the acapsular phenotype.
Role of Ndt80p in Sterol Metabolism Regulation and Azole Resistance in
Candida albicans
Authors: Sellam Adnane , Tebbji Faïza , Nantel André 
Published: June 2009

ABSTRACT

The Ndt80p transcription factor modulates azole tolerance in
Candida albicans
by controlling the expression of the gene for the drug efflux pump Cdr1p. To date, the contribution of this transcriptional modulator to drug tolerance is not yet well understood. Here, we investigate the role of Ndt80p in mediating fluconazole tolerance by determining its genome-wide occupancy using chromatin immunoprecipitation coupled to high-density tiling arrays. Ndt80p was found to bind a large number of gene promoters with diverse biological functions. Gene ontology analysis of these Ndt80p targets revealed a significant enrichment in gene products related to the cell wall, carbohydrate metabolism, stress responses, hyphal development, multidrug transport, and the cell cycle. Ndt80p was found on the promoters of ergosterol biosynthesis genes, including on the azole target Erg11p. Additionally, expression profiling was used to identify fluconazole-responsive genes that require Ndt80p for their proper expression. We found that Ndt80p is crucial for the expression of numerous fluconazole-responsive genes, especially genes involved in ergosterol metabolism. Therefore, by combining genome-wide location and transcriptional profiling, we have characterized the Ndt80p fluconazole-dependent regulon and demonstrated the key role of this global transcriptional regulator in modulating sterol metabolism and drug resistance in
C. albicans
.
Functional Genomics of Adhesion, Invasion, and Mycelial Formation in
Schizosaccharomyces pombe
Authors: Dodgson James , Avula Hema , Hoe Kwang-Lae , Kim Dong-Uk , Park Han-Oh , Hayles Jacqueline , Armstrong John 
Published: June 2009

ABSTRACT

Investigation into the switch between single-celled and filamentous forms of fungi may provide insights into cell polarity, differentiation, and fungal pathogenicity. At the molecular level, much of this investigation has fallen on two closely related budding yeasts,
Candida albicans
and
Saccharomyces cerevisiae
. Recently, the much more distant fission yeast
Schizosaccharomyces pombe
was shown to form invasive filaments after nitrogen limitation (E. Amoah-Buahin, N. Bone, and J. Armstrong, Eukaryot. Cell 4:1287-1297, 2005) and this genetically tractable organism provides an alternative system for the study of dimorphic growth. Here we describe a second mode of mycelial formation of
S. pombe
, on rich media. Screening of an
S. pombe
haploid deletion library identified 12 genes required for mycelial development which encode potential transcription factors, orthologues of
S. cerevisiae
Sec14p and Tlg2p, and the formin For3, among others. These were further grouped into two phenotypic classes representing different stages of the process. We show that galactose-dependent cell adhesion and actin assembly are both required for mycelial formation and mutants lacking a range of genes controlling cell polarity all produce mycelia but with radically altered morphology.