bluuebunny/crossref_metadata_2025_split huggingface dataset:
Regulation of Mannose Phosphotransferase System Permease and Virulence Gene Expression in
Listeria monocytogenes
by the EII
t
Man
Transporter
Authors: Vu-Khac Hung , Miller Kurt W. 
Published: September 2009

ABSTRACT

The EII
t
Man
phosphotransferase system (PTS) permease encoded by the
mpt
operon is the principal glucose transporter in
Listeria monocytogenes.
EII
t
Man
participates in glucose-mediated carbon catabolite repression (CCR) and downregulation of virulence gene expression, and it is the receptor for class IIa bacteriocins. The regulation of this important protein and its roles in gene control were examined using derivatives of strain EGD-e in which the
mpt
operon or its regulatory genes,
manR
and lmo0095, were deleted. Real-time reverse transcription-PCR analysis showed that the
mpt
mRNA level was 10- and 100-fold lower in the lmo0095 and
manR
deletion strains, respectively. The
manR
mRNA level was higher in the
mpt
deletion mutant in medium lacking glucose, possibly due to disruption of a regulatory process that normally downregulates
manR
transcription in the absence of this sugar. Analysis of the
mpt
deletion mutant also showed that EII
t
Man
participates to various degrees in glucose-mediated CCR of PTS operons. CCR of the lmo0027 gene, which encodes a β-glucoside PTS transporter, required expression of EII
t
Man
. In contrast, genes in two mannose PTS operons (lmo0024, lmo1997, and lmo2002) were repressed by glucose even when EII
t
Man
was not synthesized. A third mannose PTS operon,
mpo
, was not regulated by glucose or by the level of EII
t
Man
. Finally, the mRNA levels for five genes in the
prfA
virulence gene cluster were two- to fourfold higher in the
mpt
deletion mutant. The results show that EII
t
Man
participates to various extents in glucose-mediated CCR of PTS operons and makes a small, albeit significant, contribution to downregulation of virulence gene transcription by glucose in strain EGD-e.
Comparative Analyses of Prophage-Like Elements Present in Bifidobacterial Genomes
Authors: Ventura Marco , Turroni Francesca , Lima-Mendez Gipsi , Foroni Elena , Zomer Aldert , Duranti Sabrina , Giubellini Vanessa , Bottacini Francesca , Horvath Philippe , Barrangou Rodolphe , Sela David A. , Mills David A. , van Sinderen Douwe 
Published: September 2009

ABSTRACT

So far, only scarce and rather diffuse information is available on bacteriophages infecting members of the genus
Bifidobacterium
. In the current study, we investigated the genetic organization, phylogenetic relationships, and, in some cases, transcription profiles and inducibility of 19 prophage-like elements present on the individual chromosomes of nine bifidobacterial strains, which represent six different species.
Processivity, Synergism, and Substrate Specificity of
Thermobifida fusca
Cel6B
Authors: Vuong Thu V. , Wilson David B. 
Published: September 2009

ABSTRACT

A relationship between processivity and synergism has not been reported for cellulases, although both characteristics are very important for hydrolysis of insoluble substrates. Mutation of two residues located in the active site tunnel of
Thermobifida fusca
exocellulase Cel6B increased processivity on filter paper. Surprisingly, mixtures of the Cel6B mutant enzymes and
T. fusca
endocellulase Cel5A did not show increased synergism or processivity, and the mutant enzyme which had the highest processivity gave the poorest synergism. This study suggests that improving exocellulase processivity might be not an effective strategy for producing improved cellulase mixtures for biomass conversion. The inverse relationship between the activities of many of the mutant enzymes with bacterial microcrystalline cellulose and their activities with carboxymethyl cellulose indicated that there are differences in the mechanisms of hydrolysis for these substrates, supporting the possibility of engineering Cel6B to target selected substrates.
Seasonal Distribution of Cyprinid Herpesvirus 3 in Lake Biwa, Japan
Authors: Minamoto Toshifumi , Honjo Mie N. , Kawabata Zen'ichiro 
Published: September 2009

ABSTRACTThe seasonal distribution of the cyprinid herpesvirus 3 (CyHV-3) in Lake Biwa, Japan, was investigated. CyHV-3 was distributed all over the lake 5 years after the first outbreak. The mean concentration of CyHV-3 in water showed annual oscillation, with a peak in the summer and a trough in winter. Our results suggested that CyHV-3 is present at high density in reductive environments, such as reed zones and turbid or eutrophic water.
Identity of the Growth-Limiting Nutrient Strongly Affects Storage Carbohydrate Accumulation in Anaerobic Chemostat Cultures of
Saccharomyces cerevisiae
Authors: Hazelwood Lucie A. , Walsh Michael C. , Luttik Marijke A. H. , Daran-Lapujade Pascale , Pronk Jack T. , Daran Jean-Marc 
Published: September 2009

ABSTRACT

Accumulation of glycogen and trehalose in nutrient-limited cultures of
Saccharomyces cerevisiae
is negatively correlated with the specific growth rate. Additionally, glucose-excess conditions (i.e., growth limitation by nutrients other than glucose) are often implicated in high-level accumulation of these storage carbohydrates. The present study investigates how the identity of the growth-limiting nutrient affects accumulation of storage carbohydrates in cultures grown at a fixed specific growth rate. In anaerobic chemostat cultures (dilution rate, 0.10 h
−1
) of
S. cerevisiae
, the identity of the growth-limiting nutrient (glucose, ammonia, sulfate, phosphate, or zinc) strongly affected storage carbohydrate accumulation. The glycogen contents of the biomass from glucose- and ammonia-limited cultures were 10- to 14-fold higher than those of the biomass from cultures grown under the other three glucose-excess regimens. Trehalose levels were specifically higher under nitrogen-limited conditions. These results demonstrate that storage carbohydrate accumulation in nutrient-limited cultures of
S. cerevisiae
is not a generic response to excess glucose but instead is strongly dependent on the identity of the growth-limiting nutrient. While transcriptome analysis of wild-type and
msn2
Δ
msn4
Δ strains confirmed that transcriptional upregulation of glycogen and trehalose biosynthesis genes is mediated by Msn2p/Msn4p, transcriptional regulation could not quantitatively account for the drastic changes in storage carbohydrate accumulation. The results of assays of glycogen synthase and glycogen phosphorylase activities supported involvement of posttranscriptional regulation. Consistent with the high glycogen levels in ammonia-limited cultures, the ratio of glycogen synthase to glycogen phosphorylase in these cultures was up to eightfold higher than the ratio in the other glucose-excess cultures.
Labeled
Trichoderma reesei
Cellulase as a Marker for
Acanthamoeba
Cyst Wall Cellulose in Infected Tissues
Authors: Derda Monika , Winiecka-Krusnell Jadwiga , Linder Markus B. , Linder Ewert 
Published: September 2009

ABSTRACT

Some protozoans are able to encyst as a protective response to a harmful environment. The cyst wall usually contains chitin as its main structural constituent.
Acanthamoeba
is an exception since its cyst wall contains cellulose. Specific cytochemical differentiation between cellulose and chitin by microscopy has not been possible due to the similarity of the constituent β-1,4-linked hexose backbones of these molecules. Thus, various fluorescent brightening agents and lectins bind to both cellulose and chitin. The identification of
Acanthamoeba
spp., which is based primarily on morphological and biochemical features, is labor-intensive and requires cloning and axenization. We describe a novel immunocytochemical method for identification of
Acanthamoeba
spp. based on selective binding of
Trichoderma reesei
cellulase to protozoan cyst wall cellulose. A recombinant cellulose-binding protein consisting of two cellulose-binding domains (CBDs) from
T. reesei
cellulases was coupled to the fluorescent dyes Alexa Fluor 350 and Alexa Fluor 568 or was labeled with biotin using EZ-Link sulfo-NHS-biotin. No staining reaction was observed with chitin-containing preparations of fungi. Thus, the recombinant CBDs can be used as a marker to distinguish between cellulose and chitin. This allows rapid identification of
Acanthamoeba
cyst wall cellulose in paraffin or frozen sections of infected tissues.
Cloning and Characterization of an Intracellular Esterase from the Wine-Associated Lactic Acid BacteriumOenococcus oeni
Authors: Sumby Krista M. , Matthews Angela H. , Grbin Paul R. , Jiranek Vladimir 
Published: September 2009

ABSTRACTWe report the cloning and characterization of EstB28, the first esterase to be so characterized from the wine-associated lactic acid bacterium,Oenococcus oeni. The published sequence forO. oenistrain PSU-1 was used to identify putative esterase genes and design PCR primers in order to amplify the corresponding region from strain Ooeni28, an isolate intended for inoculation of wines. In this way a 912-bp open reading frame (ORF) encoding a putative esterase of 34.5 kDa was obtained. The amino acid sequence indicated that EstB28 is a member of family IV of lipolytic enzymes and contains the GDSAG motif common to other lactic acid bacteria. This ORF was cloned intoEscherichia coliusing an appropriate expression system, and the recombinant esterase was purified. Characterization of EstB28 revealed that the optimum temperature, pH, and ethanol concentration were 40°C, pH 5.0, and 28% (vol/vol), respectively. EstB28 also retained marked activity under conditions relevant to winemaking (10 to 20°C, pH 3.5, 14% [vol/vol] ethanol). Kinetic constants were determined for EstB28 withp-nitrophenyl (pNP)-linked substrates ranging in chain length from C2to C18. EstB28 exhibited greatest specificity for C2to C4pNP-linked substrates.
Prevalence of
Cardinium
Bacteria in Planthoppers and Spider Mites and Taxonomic Revision of “
Candidatus
Cardinium hertigii” Based on Detection of a New
Cardinium
Group from Biting Midges
Authors: Nakamura Yuki , Kawai Sawako , Yukuhiro Fumiko , Ito Saiko , Gotoh Tetsuo , Kisimoto Ryoiti , Yanase Tohru , Matsumoto Yukiko , Kageyama Daisuke , Noda Hiroaki 
Published: September 2009

ABSTRACT

Cardinium
bacteria, members of the phylum
Cytophaga
-
Flavobacterium
-
Bacteroides
(CFB), are intracellular bacteria in arthropods that are capable of inducing reproductive abnormalities in their hosts, which include parasitic wasps, mites, and spiders. A high frequency of
Cardinium
infection was detected in planthoppers (27 out of 57 species were infected). A high frequency of
Cardinium
infection was also found in spider mites (9 out of 22 species were infected). Frequencies of double infection by
Cardinium
and
Wolbachia
bacteria (
Alphaproteobacteria
capable of manipulating reproduction of their hosts) were disproportionately high in planthoppers but not in spider mites. A new group of bacteria, phylogenetically closely related to but distinct from previously described
Cardinium
bacteria (based on 16S rRNA and
gyrB
genes) was found in 4 out of 25 species of
Culicoides
biting midges. These bacteria possessed a microfilament-like structure that is a morphological feature previously found in
Cardinium
and
Paenicardinium
. The bacteria close to the genus
Cardinium
consist of at least three groups, A, B, and C. Group A is present in various species of arthropods and was previously referred to as “
Candidatus
Cardinium hertigii,” group B is present in plant parasitic nematodes and was previously referred to as “
Candidatus
Paenicardinium endonii,” and group C is present in
Culicoides
biting midges. On the basis of morphological and molecular data, we propose that the nomenclature of these three groups be integrated into a single species, “
Candidatus
Cardinium hertigii.”
Isolation and Identification of Novel Microcystin-Degrading Bacteria
Authors: Manage Pathmalal M. , Edwards Christine , Singh Brajesh K. , Lawton Linda A. 
Published: September 2009

ABSTRACT

Of 31 freshwater bacterial isolates screened using the Biolog MT2 assay to determine their metabolism of the microcystin LR, 10 were positive. Phylogenetic analysis (16S rRNA) identified them as
Arthrobacter
spp.,
Brevibacterium
sp., and
Rhodococcus
sp. This is the first report of microcystin degraders that do not belong to the
Proteobacteria
.
Mss11, a Transcriptional Activator, Is Required for Hyphal Development in
Candida albicans
Authors: Su Chang , Li Yandong , Lu Yang , Chen Jiangye 
Published: September 2009

ABSTRACT

Candida albicans
undergoes a morphological transition from yeast to hyphae in response to a variety of stimuli and growth conditions. We previously isolated a LisH domain containing transcription factor Flo8, which is essential for hyphal development in
C. albicans
. To search the putative binding partner of Flo8 in
C. albicans
, we identified
C. albicans
Mss11, a functional homolog of
Saccharomyces cerevisiae
Mss11, which also contains a LisH motif at its N terminus.
C. albicans
Mss11 can interact with Flo8 via the LisH motif by in vivo coimmunoprecipitation. The results of a chromatin immunoprecipitation (ChIP) assay showed that more Mss11 and Flo8 proteins bound to the upstream activating sequence region of
HWP1
promoter in hyphal cells than in yeast cells, and the increased binding of each of these two proteins responding to hyphal induction was dependent on the other. Overexpression of
MSS11
enhanced filamentous growth. Deletion of
MSS11
caused a profound defect in hyphal development and the induction of hypha-specific genes. Our data suggest that Mss11 functions as an activator in hyphal development of
C. albicans
. Furthermore, overexpression of
FLO8
can bypass the requirement of Mss11 in filamentous formation, whereas overexpression of
MSS11
failed to promote hyphae growth in
flo8
mutants. In summary, we show that the expression level of
MSS11
increases during hyphal induction, and the enhanced expression of
MSS11
may contribute to cooperative binding of Mss11 and Flo8 to the
HWP1
promoter.
Chitinases Are Essential for Sexual Development but Not Vegetative Growth in
Cryptococcus neoformans
Authors: Baker Lorina G. , Specht Charles A. , Lodge Jennifer K. 
Published: September 2009

ABSTRACT

Cryptococcus neoformans
is an opportunistic pathogen that mainly infects immunocompromised individuals. The fungal cell wall of
C. neoformans
is an excellent target for antifungal therapies since it is an essential organelle that provides cell structure and integrity. Importantly, it is needed for localization or attachment of known virulence factors, including melanin, phospholipase, and the polysaccharide capsule. The polysaccharide fraction of the cryptococcal cell wall is a complex structure composed of chitin, chitosan, and glucans. Chitin is an indispensable component of many fungal cell walls that contributes significantly to cell wall strength and integrity. Fungal cell walls are very dynamic, constantly changing during cell division and morphogenesis. Hydrolytic enzymes, such as chitinases, have been implicated in the maintenance of cell wall plasticity and separation of the mother and daughter cells at the bud neck during vegetative growth in yeast. In
C. neoformans
we identified four predicted endochitinases,
CHI2
,
CHI21
,
CHI22
, and
CHI4
, and a predicted exochitinase, hexosaminidase,
HEX1
. Enzymatic analysis indicated that Chi2, Chi22, and Hex1 actively degraded chitinoligomeric substrates. Chi2 and Hex1 activity was associated mostly with the cellular fraction, and Chi22 activity was more prominent in the supernatant. The enzymatic activity of Hex1 increased when grown in media containing only
N
-acetylglucosamine as a carbon source, suggesting that its activity may be inducible by chitin degradation products. Using a quadruple endochitinase deletion strain, we determined that the endochitinases do not affect the growth or morphology of
C. neoformans
during asexual reproduction. However, mating assays indicated that Chi2, Chi21, and Chi4 are each involved in sexual reproduction. In summary, the endochitinases were found to be dispensable for routine vegetative growth but not sexual reproduction.
Two Novel Techniques for Determination of Polysaccharide Cross-Links Show that Crh1p and Crh2p Attach Chitin to both β(1-6)- and β(1-3)Glucan in the
Saccharomyces cerevisiae
Cell Wall
Authors: Cabib Enrico 
Published: September 2009

ABSTRACT

Previous work, using solubilization of yeast cell walls by carboxymethylation, before or after digestion with β(1-3)- or β(1-6)glucanase, followed by size chromatography, showed that the transglycosylases Crh1p and Crh2p/Utr2p were redundantly required for the attachment of chitin to β(1-6)glucan. With this technique,
crh1
Δ
crh2
Δ mutants still appeared to contain a substantial percentage of chitin linked to β(1-3)glucan. Two novel procedures have now been developed for the analysis of polysaccharide cross-links in the cell wall. One is based on the affinity of curdlan, a β(1-3)glucan, for β(1-3)glucan chains in carboxymethylated cell walls. The other consists of in situ deacetylation of cell wall chitin, generating chitosan, which can be extracted with acetic acid, either directly (free chitosan) or after digestion with different glucanases (bound chitosan). Both methodologies indicated that all of the chitin in
crh1
Δ
crh2
Δ strains is free. Reexamination of the previously used procedure revealed that the β(1-3)glucanase preparation used (zymolyase) is contaminated with a small amount of endochitinase, which caused erroneous results with the double mutant. After removing the chitinase from the zymolyase, all three procedures gave coincident results. Therefore, Crh1p and Crh2p catalyze the transfer of chitin to both β(1-3)- and β(1-6)glucan, and the biosynthetic mechanism for all chitin cross-links in the cell wall has been established.
The
rkp-1
Cluster Is Required for Secretion of Kdo Homopolymeric Capsular Polysaccharide in
Sinorhizobium meliloti
Strain Rm1021
Authors: Müller Maike G. , Forsberg Lennart S. , Keating David H. 
Published: September 2009

ABSTRACT

Under conditions of nitrogen stress, leguminous plants form symbioses with soil bacteria called rhizobia. This partnership results in the development of structures called root nodules, in which differentiated endosymbiotic bacteria reduce molecular dinitrogen for the host. The establishment of rhizobium-legume symbioses requires the bacterial synthesis of oligosaccharides, exopolysaccharides, and capsular polysaccharides. Previous studies suggested that the 3-deoxy-
d
-manno-oct-2-ulopyranosonic acid (Kdo) homopolymeric capsular polysaccharide produced by strain
Sinorhizobium meliloti
Rm1021 contributes to symbiosis with
Medicago sativa
under some conditions. However, a conclusive symbiotic role for this polysaccharide could not be determined due to a lack of mutants affecting its synthesis. In this study, we have further characterized the synthesis, secretion, and symbiotic function of the Kdo homopolymeric capsule. We showed that mutants lacking the enigmatic
rkp-1
gene cluster fail to display the Kdo capsule on the cell surface but accumulate an intracellular polysaccharide of unusually high
M
r
. In addition, we have demonstrated that mutations in
kdsB2
, smb20804, and smb20805 affect the polymerization of the Kdo homopolymeric capsule. Our studies also suggest a role for the capsular polysaccharide in symbiosis. Previous reports have shown that the overexpression of
rkpZ
from strain Rm41 allows for the symbiosis of
exoY
mutants of Rm1021 that are unable to produce the exopolysaccharide succinoglycan. Our results demonstrate that mutations in the
rkp-1
cluster prevent this phenotypic suppression of
exoY
mutants, although mutations in
kdsB2
, smb20804, and smb20805 have no effect.
Catabolism of Raffinose, Sucrose, and Melibiose in
Erwinia chrysanthemi
3937
Authors: Hugouvieux-Cotte-Pattat Nicole , Charaoui-Boukerzaza Sana 
Published: September 2009

ABSTRACT

Erwinia chrysanthemi
(
Dickeya dadantii
) is a plant pathogenic bacterium that has a large capacity to degrade the plant cell wall polysaccharides. The present study reports the metabolic pathways used by
E. chrysanthemi
to assimilate the oligosaccharides sucrose and raffinose, which are particularly abundant plant sugars.
E. chrysanthemi
is able to use sucrose, raffinose, or melibiose as a sole carbon source for growth. The two gene clusters
scrKYABR
and
rafRBA
are necessary for their catabolism. The phenotypic analysis of
scr
and
raf
mutants revealed cross-links between the assimilation pathways of these oligosaccharides. Sucrose catabolism is mediated by the genes
scrKYAB
. While the
raf
cluster is sufficient to catabolize melibiose, it is incomplete for raffinose catabolism, which needs two additional steps that are provided by
scrY
and
scrB
. The
scr
and
raf
clusters are controlled by specific repressors, ScrR and RafR, respectively. Both clusters are controlled by the global activator of carbohydrate catabolism, the cyclic AMP receptor protein (CRP).
E. chrysanthemi
growth with lactose is possible only for mutants with a derepressed nonspecific lactose transport system, which was identified as RafB. RafR inactivation allows the bacteria to the assimilate the novel substrates lactose, lactulose, stachyose, and melibionic acid. The
raf
genes also are involved in the assimilation of α- and β-methyl-
d
-galactosides. Mutations in the
raf
or
scr
genes did not significantly affect
E. chrysanthemi
virulence. This could be explained by the large variety of carbon sources available in the plant tissue macerated by
E. chrysanthemi
.
PhoB Regulates Motility, Biofilms, and Cyclic di-GMP inVibrio cholerae
Authors: Pratt Jason T. , McDonough EmilyKate , Camilli Andrew 
Published: September 2009

ABSTRACTSignaling through the second messenger cyclic di-GMP (c-di-GMP) is central to the life cycle ofVibrio cholerae. However, relatively little is known about the signaling mechanism, including the specific external stimuli that regulate c-di-GMP concentration. Here, we show that the phosphate responsive regulator PhoB regulates an operon,acgAB, which encodes c-di-GMP metabolic enzymes. We show that induction ofacgABby PhoB positively regulatesV. choleraemotility in vitro and that PhoB regulates expression ofacgABat late stages duringV. choleraeinfection in the infant mouse small intestine. These data support a model whereby PhoB becomes activated at a late stage of infection in preparation for dissemination ofV. choleraeto the aquatic environment and suggest that the concentration of exogenous phosphate may become limited at late stages of infection.