bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eap1p, an Adhesin That Mediates
Candida albicans
Biofilm Formation In Vitro and In Vivo
Authors: Li Fang , Svarovsky Michael J. , Karlsson Amy J. , Wagner Joel P. , Marchillo Karen , Oshel Philip , Andes David , Palecek Sean P. 
Published: April 2007

ABSTRACT

Candida albicans
is the leading cause of systemic fungal infections in immunocompromised humans. The ability to form biofilms on surfaces in the host or on implanted medical devices enhances
C. albicans
virulence, leading to antimicrobial resistance and providing a reservoir for infection. Biofilm formation is a complex multicellular process consisting of cell adhesion, cell growth, morphogenic switching between yeast form and filamentous states, and quorum sensing. Here we describe the role of the
C. albicans EAP1
gene, which encodes a glycosylphosphatidylinositol-anchored, glucan-cross-linked cell wall protein, in adhesion and biofilm formation in vitro and in vivo. Deleting
EAP1
reduced cell adhesion to polystyrene and epithelial cells in a gene dosage-dependent manner. Furthermore,
EAP1
expression was required for
C. albicans
biofilm formation in an in vitro parallel plate flow chamber model and in an in vivo rat central venous catheter model.
EAP1
expression was upregulated in biofilm-associated cells in vitro and in vivo. Our results illustrate an association between Eap1p-mediated adhesion and biofilm formation in vitro and in vivo.
Stable Preanaphase Spindle Positioning Requires Bud6p and an Apparent Interaction between the Spindle Pole Bodies and the Neck
Authors: Haarer Brian K. , Helfant Astrid Hoes , Nelson Scott A. , Cooper John A. , Amberg David C. 
Published: April 2007

ABSTRACT

Faithful partitioning of genetic material during cell division requires accurate spatial and temporal positioning of nuclei within dividing cells. In
Saccharomyces cerevisiae
, nuclear positioning is regulated by an elegant interplay between components of the actin and microtubule cytoskeletons. Regulators of this process include Bud6p (also referred to as the actin-interacting protein Aip3p) and Kar9p, which function to promote contacts between cytoplasmic microtubule ends and actin-delimited cortical attachment points. Here, we present the previously undetected association of Bud6p with the cytoplasmic face of yeast spindle pole bodies, the functional equivalent of metazoan centrosomes. Cells lacking Bud6p show exaggerated movements of the nucleus between mother and daughter cells and display reduced amounts of time a given spindle pole body spends in close association with the neck region of budding cells. Furthermore, overexpression of
BUD6
greatly enhances interactions between the spindle pole body and mother-bud neck in a spindle alignment-defective dynactin mutant. These results suggest that association of either spindle pole body with neck components, rather than simply entry of a spindle pole body into the daughter cell, provides a positive signal for the progression of mitosis. We propose that Bud6p, through its localization at both spindle pole bodies and at the mother-bud neck, supports this positive signal and provides a regulatory mechanism to prevent excessive oscillations of preanaphase nuclei, thus reducing the likelihood of mitotic delays and nuclear missegregation.
Structural Properties of Periplasmic SodCI That Correlate with Virulence in
Salmonella enterica
Serovar Typhimurium
Authors: Krishnakumar Radha , Kim Byoungkwan , Mollo Elizabeth A. , Imlay James A. , Slauch James M. 
Published: April 2007

ABSTRACT

Salmonella enterica
strains survive and propagate in macrophages by both circumventing and resisting the antibacterial effectors normally delivered to the phagosome. An important aspect of
Salmonella
resistance is the production of periplasmic superoxide dismutase to combat phagocytic superoxide.
S. enterica
serovar Typhimurium strain 14028 produces two periplasmic superoxide dismutases: SodCI and SodCII. Both enzymes are produced during infection, but only SodCI contributes to virulence in the animal. Although 60% identical to SodCII at the amino acid level with very similar enzymatic properties, SodCI is dimeric, protease resistant, and tethered within the periplasm via a noncovalent interaction. In contrast, SodCII is monomeric and protease sensitive and is released from the periplasm normally by osmotic shock. We have constructed an enzymatically active monomeric SodCI enzyme by site-directed mutagenesis. The resulting protein was released by osmotic shock and sensitive to protease and could not complement the loss of wild-type dimeric SodCI during infection. To distinguish which property is most critical during infection, we cloned and characterized related SodC proteins from a variety of bacteria.
Brucella abortus
SodC was monomeric and released by osmotic shock but was protease resistant and could complement SodCI in the animal. These data suggest that protease resistance is a critical property that allows SodCI to function in the harsh environment of the phagosome to combat phagocytic superoxide. We propose a model to account for the various properties of SodCI and how they contribute to bacterial survival in the phagosome.
σ
E
Regulates and Is Regulated by a Small RNA in
Escherichia coli
Authors: Thompson Karl M. , Rhodius Virgil A. , Gottesman Susan 
Published: April 2007

ABSTRACT

RybB is a small, Hfq-binding noncoding RNA originally identified in a screen of conserved intergenic regions in
Escherichia coli
. Fusions of the
rybB
promoter to
lacZ
were used to screen plasmid genomic libraries and genomic transposon mutants for regulators of
rybB
expression. A number of plasmids, including some carrying
rybB
, negatively regulated the fusion. An insertion in the
rep
helicase and one upstream of
dnaK
decreased expression of the fusion. Multicopy suppressors of these insertions led to identification of two plasmids that stimulated the fusion. One contained the gene for the response regulator OmpR; the second contained
mipA
, encoding a murein hydrolase. The involvement of MipA and OmpR in cell surface synthesis suggested that the
rybB
promoter might be dependent on σ
E
. The sequence upstream of the +1 of
rybB
contains a consensus σ
E
promoter. The activity of
rybB
-
lacZ
was increased in cells lacking the RseA anti-sigma factor and when σ
E
was overproduced from a heterologous promoter. The activity of
rybB
-
lacZ
and the detection of RybB were totally abolished in an
rpoE
-null strain. In vitro, σ
E
efficiently transcribes from this promoter. Both a
rybB
mutation and an
hfq
mutation significantly increased expression of both
rybB
-
lacZ
and
rpoE
-
lacZ
fusions, consistent with negative regulation of the σ
E
response by RybB and other small RNAs. Based on the plasmid screens, NsrR, a repressor sensitive to nitric oxide, was also found to negatively regulate σ
E
-dependent promoters in an RseA-independent fashion.
The Phosphotransferase System Formed by PtsP, PtsO, and PtsN Proteins Controls Production of Polyhydroxyalkanoates in
Pseudomonas putida
Authors: Velázquez Francisco , Pflüger Katharina , Cases Ildefonso , De Eugenio Laura I. , de Lorenzo Víctor 
Published: April 2007

ABSTRACT

The genome of
Pseudomonas putida
KT2440 encodes five proteins of the phosphoenolpyruvate-carbohydrate phosphotransferase system. Two of these (FruA and FruB) form a dedicated system for fructose intake, while enzyme I
Ntr
(EI
Ntr
; encoded by
ptsP
), NPr (
ptsO
), and EII
Ntr
(
ptsN
) act in concert to control the intracellular accumulation of polyhydroxyalkanoates, a typical product of carbon overflow.
Identification of the σBRegulon ofBacillus cereusand Conservation of σB-Regulated Genes in Low-GC-Content Gram-Positive Bacteria
Authors: van Schaik Willem , van der Voort Menno , Molenaar Douwe , Moezelaar Roy , de Vos Willem M. , Abee Tjakko 
Published: April 2007

ABSTRACTThe alternative sigma factor σBhas an important role in the acquisition of stress resistance in many gram-positive bacteria, including the food-borne pathogenBacillus cereus. Here, we describe the identification of the set of σB-regulated genes inB. cereusby DNA microarray analysis of the transcriptome upon a mild heat shock. Twenty-four genes could be identified as being σBdependent as witnessed by (i) significantly lower expression levels of these genes in mutants with a deletion ofsigBandrsbY(which encode the alternative sigma factor σBand a crucial positive regulator of σBactivity, respectively) than in the parental strainB. cereusATCC 14579 and (ii) increased expression of these genes upon a heat shock. Newly identified σB-dependent genes inB. cereusinclude a histidine kinase and two genes that have predicted functions in spore germination. This study shows that the σBregulon ofB. cereusis considerably smaller than that of other gram-positive bacteria. This appears to be in line with phylogenetic analyses where σBof theB. cereusgroup was placed close to the ancestral form of σBin gram-positive bacteria. The data described in this study and previous studies in which the complete σBregulon of the gram-positive bacteriaBacillus subtilis,Listeria monocytogenes, andStaphylococcus aureuswere determined enabled a comparison of the sets of σB-regulated genes in the different gram-positive bacteria. This showed that only three genes (rsbV,rsbW, andsigB) are conserved in their σBdependency in all four bacteria, suggesting that the σBregulon of the different gram-positive bacteria has evolved to perform niche-specific functions.
In Vitro Biosynthesis of Ether-Type Glycolipids in the Methanoarchaeon
Methanothermobacter thermautotrophicus
Authors: Morii Hiroyuki , Eguchi Tadashi , Koga Yosuke 
Published: April 2007

ABSTRACT

The biosynthesis of archaeal ether-type glycolipids was investigated in vitro using
Methanothermobacter thermautotrophicus
cell-free homogenates. The sole sugar moiety of glycolipids and phosphoglycolipids of the organism is the β-
d
-glucosyl-(1→6)-
d
-glucosyl (gentiobiosyl) unit. The enzyme activities of archaeol:UDP-glucose β-glucosyltransferase (monoglucosylarchaeol [MGA] synthase) and MGA:UDP-glucose β-1,6-glucosyltransferase (diglucosylarchaeol [DGA] synthase) were found in the methanoarchaeon. The synthesis of DGA is probably a two-step glucosylation: (i) archaeol + UDP-glucose → MGA + UDP, and (ii) MGA + UDP-glucose → DGA + UDP. Both enzymes required the addition of K
+
ions and archaetidylinositol for their activities. DGA synthase was stimulated by 10 mM MgCl
2
, in contrast to MGA synthase, which did not require Mg
2+
. It was likely that the activities of MGA synthesis and DGA synthesis were carried out by different proteins because of the Mg
2+
requirement and their cellular localization. MGA synthase and DGA synthase can be distinguished in cell extracts greatly enriched for each activity by demonstrating the differing Mg
2+
requirements of each enzyme. MGA synthase preferred a lipid substrate with the
sn
-2,3 stereostructure of the glycerol backbone on which two saturated isoprenoid chains are bound at the
sn
-2 and
sn
-3 positions. A lipid substrate with unsaturated isoprenoid chains or
sn
-1,2-dialkylglycerol configuration exhibited low activity. Tetraether-type caldarchaetidylinositol was also actively glucosylated by the homogenates to form monoglucosyl caldarchaetidylinositol and a small amount of diglucosyl caldarchaetidylinositol. The addition of Mg
2+
increased the formation of diglucosyl caldarchaetidylinositol. This suggested that the same enzyme set synthesized the sole sugar moiety of diether-type glycolipids and tetraether-type phosphoglycolipids.
Purification and Characterization of Mycobacterial Phospholipase A: an Activity Associated with Mycobacterial Cutinase
Authors: Parker Sarah K. , Curtin Kathryn M. , Vasil Michael L. 
Published: April 2007

ABSTRACT

We describe mycobacterial phospholipase A activity (MPLA) and, using reverse genetics, have associated this activity with putative mycobacterial cutinase. PLAs, which hydrolyze fatty acids on phospholipids, play a significant role in human inflammatory states and disease pathogenesis. In prokaryotes, the recognition of their role in virulence is more recent. Cutinases are serine esterases whose primary substrate is cutin, the waxy exterior layer of plants.
Mycobacterium tuberculosis
has maintained seven putative cutinases, though it should not encounter cutin; we demonstrate that known cutinases and MPLA cleave phospholipids in a PLA-type manner and also hydrolyze Tween. We analyzed cutinase motifs in mycobacteria and found the motif very prevalent. All mycobacteria tested had MPLA activity. These studies suggest an alternative use for putative cutinases by the
M. tuberculosis
group that is likely related to MPLA activity and lipid metabolism.
Characterization of a C—C Bond Hydrolase fromSphingomonas wittichiiRW1 with Novel Specificities towards Polychlorinated Biphenyl Metabolites
Authors: Seah Stephen Y. K. , Ke Jiyuan , Denis Geoffroy , Horsman Geoff P. , Fortin Pascal D. , Whiting Cheryl J. , Eltis Lindsay D. 
Published: April 2007

ABSTRACTSphingomonas wittichiiRW1 degrades chlorinated dibenzofurans and dibenzo-p-dioxins viametacleavage. We used inverse PCR to amplifydxnB2, a gene encoding one of threemeta-cleavage product (MCP) hydrolases identified in the organism that are homologues of BphD involved in biphenyl catabolism. Purified DxnB2 catalyzed the hydrolysis of 8-OH 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate (HOPDA) approximately six times faster than for HOPDA at saturating substrate concentrations. Moreover, the specificity of DxnB2 for HOPDA (kcat/Km= 1.2 × 107M−1s−1) was about half that of the BphDs ofBurkholderia xenovoransLB400 andRhodococcus globerulusP6, two potent polychlorinated biphenyl (PCB)-degrading strains. Interestingly, DxnB2 transformed 3-Cl and 4-OH HOPDAs, compounds that inhibit the BphDs and limit PCB degradation. DxnB2 had a higher specificity for 9-Cl HOPDA than for HOPDA but a lower specificity for 8-Cl HOPDA (kcat/Km= 1.7 × 106M−1s−1), the chlorinated analog of 8-OH HOPDA produced during dibenzofuran catabolism. Phylogenetic analyses based on structure-guided sequence alignment revealed that DxnB2 belongs to a previously unrecognized class of MCP hydrolases, evolutionarily divergent from the BphDs although the physiological substrates of both enzyme types are HOPDAs. However, both classes of enzymes have mainly small hydrophobic residues lining the subsite that binds the C-6 phenyl of HOPDA, in contrast to the bulky hydrophobic residues (Phe106, Phe135, Trp150, and Phe197) found in the class II enzymes that prefer substrates possessing a C-6 alkyl. Thr196 and/or Asn203 appears to be an important determinant of specificity for DxnB2, potentially forming hydrogen bonds with the 8-OH substituent. This study demonstrates that the substrate specificities of evolutionarily divergent hydrolases may be useful for degrading mixtures of pollutants, such as PCBs.
Flagellar Motility Is Critical forListeria monocytogenesBiofilm Formation
Authors: Lemon Katherine P. , Higgins Darren E. , Kolter Roberto 
Published: April 2007

ABSTRACTThe food-borne pathogenListeria monocytogenesattaches to environmental surfaces and forms biofilms that can be a source of food contamination, yet little is known about the molecular mechanisms of its biofilm development. We observed that nonmotile mutants were defective in biofilm formation. To investigate how flagella might function during biofilm formation, we compared the wild type with flagellum-minus and paralyzed-flagellum mutants. Both nonmotile mutants were defective in biofilm development, presumably at an early stage, as they were also defective in attachment to glass during the first few hours of surface exposure. This attachment defect could be significantly overcome by providing exogenous movement toward the surface via centrifugation. However, this centrifugation did not restore mature biofilm formation. Our results indicate that it is flagellum-mediated motility that is critical for both initial surface attachment and subsequent biofilm formation. Also, any role forL. monocytogenesflagella as adhesins on abiotic surfaces appears to be either minimal or motility dependent under the conditions we examined.
2007: A Kairos Moment for Public Theology
Authors: Storrar William 
Published: April 2007

AbstractThe simultaneous launch of the International Journal of Public Theology and its sponsoring Global Network for Public Theology represents a 'kairos' moment of opportunity for theologians and other scholars working in the emerging field of interdisciplinary theological inquiry into contemporary public issues. Such moments happen, this article argues, when a disruptive social experience calls for the response of collaborative theological inquiry into the public issues generated by such disruptions. By telling an autobiographical story of a public theologian and by reflecting on the history of the pioneering Edinburgh University Centre for Theology and Public Issues, the article identifies common factors that have led a growing number of scholars and research centres around the world to identify with the phrase 'public theology'. Such factors include a commitment to the ecclesial and the emancipatory dimensions of doing theology and employing research methods that include the marginalized as agents of social transformation.
Public Theology as Christian Witness: Exploring the Genre
Authors: de Gruchy John 
Published: April 2007

AbstractThis article explores the genre of public theology from the specific context of South Africa, while looking for the points of commonality set out by Duncan Forrester. Since the phrase 'public theology' refers to an engagement between theology and politics in specific locations, its content will be diverse and, yet, there is much that diverse public theologies share. Moreover, good practice in public theology requires that secularity and religious diversity are taken seriously. Consequently, Christian witness in secular democratic society means promoting the common good by witnessing to core values rather than seeking privilege for the Christian religion. In particular, this article offers the anti-apartheid and other activities of Joseph Wing and Douglas Bax, as well as the academic work of Denise Ackermann and the political service of Alex Boraine as examples of good practice in public theology in South Africa. The article concludes with the affirmation that public theology implies engagement in matters of public importance either through debate or action and always with self-critical theological reflection.
Class III antiarrhythmic methanesulfonanilides inhibit leukocyte recruitment in zebrafish
Authors: Brown Simon B , Tucker Carl S , Ford Christopher , Lee Yfe , Dunbar Donald R , Mullins John J 
Published: April 2007

AbstractUnderstanding fundamental molecular mechanisms that govern the transmigration and interstitial migration of leukocytes to sites of tissue damage and infection is of potential significance in identifying novel therapeutic targets for the management of chronic inflammatory disorders. CD31 is a mammalian cell adhesion molecule that regulates the recruitment of leukocytes from the circulation. Our recent unpublished work has suggested that homophilic ligation of CD31 can negatively regulate the ether-à-go-go-related gene (ERG) current within leukocytes to regulate cell-cell adhesion. To validate and probe the functional significance of ERG in leukocytes, we developed an infected wound model of inflammation in zebrafish and assessed the efficacy of two ERG-specific inhibitors, dofetilide and E4031, as well as an ERG-specific antisense RNA morpholino on neutrophil recruitment. Our data confirm a hitherto undescribed role for ERG in leukocytes, where inhibition or translational knockdown of ERG resulted in significant attenuation of the inflammatory response to an infectious stimulus. Inhibition of ERG was verified independently by a decrease in the ventricular heart rate, where ERG also functions in the repolarization of the cardiac action potential. Our results suggest that ERG-specific Class III antiarrhythmic drugs can modulate inflammatory responses to infection.
Understanding phospholipase D (PLD) using leukocytes: PLD involvement in cell adhesion and chemotaxis
Authors: Gomez-Cambronero Julian , Di Fulvio Mauricio , Knapek Katie 
Published: April 2007

AbstractPhospholipase D (PLD) is an enzyme that catalyzes the conversion of membrane phosphatidylcholine to choline and phosphatidic acid (PA; a second messenger). PLD is expressed in nearly all types of leukocytes and has been associated with phagocytosis, degranulation, microbial killing, and leukocyte maturation. With the application of recently developed molecular tools (i.e., expression vectors, silencing RNA, and specific antibodies), the demonstration of a key role for PLD in those and related cellular actions has contributed to a better awareness of its importance. A case in point is the recent findings that RNA interference-mediated depletion of PLD results in impaired leukocyte adhesion and chemotaxis toward a gradient of chemokines, implying that PLD is necessary for leukocyte movement. We forecast that based on results such as those, leukocytes may prove to be useful tools to unravel still-unresolved mechanistic issues in the complex biology of PLD. Three such issues are considered here: first, whether the cellular actions of PLD are mediated entirely by PA (the product of its enzymatic reaction) or whether PLD by itself interacts with other protein signaling molecules; second, the current difficulty of defining a “PA consensus site” in the various intracellular protein targets of PA; and third, the resolution of specific PLD location (upstream or downstream) in a particular effector signaling cascade. There are reasons to expect that leukocytes and their leukemic cell line counterparts will continue yielding invaluable information to cell biologists to resolve standing molecular and functional issues concerning PLD.
Synthesis and Properties of Liquid-Crystalline-Conjugated Polymers
Authors: Akagi Kazuo 
Published: April 2007

Abstract
We have synthesized novel liquid-crystalline (LC)-conducting polymers by introducing LC groups into acetylene monomers and polymerizing them with Ziegler–Natta, metathesis, and rhodium-based catalysts. All polymers prepared were soluble in organic solvents and had a thermotropic liquid crystallinity characterized with fan-shaped texture in polarizing optical microscopy. Phase transitions and the corresponding enthalpy changes were also evaluated by means of differential scanning calorimeter (DSC). High-order structures of the polymers were investigated by means of X-ray diffraction (XRD) analyses. XRD measurements showed that the polymers had layered structures in the LC state to give smectic A phases, which is in agreement with the results from the polarizing optical microscope. We found that the LC side chains alternate on both sides of the polyene chain, giving rise to a stereoregular sequence, such as head–head–tail–tail linkage. Macroscopic alignments of the polymers were performed in the liquid-crystalline phase by shear stress or a magnetic force field of 0.7–1.0 Tesla, which resulted in an enhancement by two orders of magnitude in the electrical conductivity of iodine-doped cast films. Orientation behaviors of the polymers as well as the monomers were investigated using fused-state 13C NMR measurements with proton dipolar decoupling. Analysis of chemical shift tensors was also carried out to evaluate the order parameter and shielding anisotropy in the LC phase. As a result, we demonstrated that LC-conjugated polymers uniaxially aligned due to the magnetically forced alignment of the LC side-chain, giving rise to a monodomain structure.