bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction
Authors: Colvin Sarah
Published: January 2004

The essays collected in this volume have been developed from selected papers first presented at the Women in German Studies conference Myths and Mythmaking, which was held at the University of Edinburgh in July 2000.
Multiple Refractions, or Winning Movement out of Myth: Barbara Köhler's Poem Cycle ‘Elektra. Spiegelungen’
Authors: Paul Georgina
Published: January 2004

Barbara Köhler's poem cycle ‘Elektra. Spiegelungen’ (written 1984–5, first published 1991) is the response of the female poet to Heiner Müller's Die Hamletmaschine (1977). The paper examines the relation between Müller's Ophelia/Elektra, who swears revenge while being bound into a wheelchair in the course of the final scene, and Köhler's multiple figure (‘die gestalt nähert sich wird körper verdoppelt verviel‐/facht eins in allen bildern neigt sie sich zu und fordert’, I), focusing in particular on the strategies with which the woman writer seeks to elicit movement from the potential entrapment in immobility of the female figure in the mirror‐images of male‐created myth. If iconoclasm is rejected as an option –‘und schlag ich dann treffe ich/dein gesicht und mein gesicht//zerfällt’, III – the multiple refractions created by the eight‐poem cycle nevertheless win a liberating movement from reductive mythical images of Woman (in contrast to Christa Wolf's re‐entrapment of her Kassandra figure in an alternative heroic narrative in her 1983 Erzählung), opening out into a utopian space –‘traum hinter dem irrgarten beginnt eine landschaft’, VIII – in the final poem in the cycle.
Pina Bausch Choreographs Blaubart: A Transgressive or Regressive Act?
Authors: Mumford Meg
Published: January 2004

Pina Bausch's Blaubart – Beim Anhören einer Tonbandaufnahme von Béla Bartók's Oper ‘Herzog Blaubarts Burg’ (1977) marked the beginning of the choreographer's trademark challenge to the boundaries between dance and theatre through collaborative improvisation and verbal expression. Given the extent to which the piece is transgressive, it is intriguing that it should be so strongly permeated by a musical setting which has often been described as a regressively misogynist appropriation of Charles Perrault's fairytales (1697). As Mererid Puw Davies has pointed out, Balázs's libretto and Bartók's opera Herzog Blaubarts Burg (1910/11) belong to a bleak canon typified by tragic, non‐utopian endings, a sympathetic portrayal of murderous Bluebeard and the disempowerment of female protagonists.

When Bausch's work toured North America in 1984 it received much negative comment because of its unremitting presentation of violent gender relations and its cultural specificity. The following study questions whether the production is regressively bleak, contending instead that the experience of a fatalistic vision is dialogically opposed to a more utopian constructivist critique of learned sado‐masochistic behaviour. It also explores the way Bausch's Märchen articulates the interrelationship between gender and national cultural concerns, both darkly embodying and critically resisting the dynamics of authoritarian civilising structures.
Taking Back the Myth and Magic: ‘The Heroic Testament’ of Irmtraud Morgner
Authors: Herminghouse Patricia
Published: January 2004

Das heroische Testament, the posthumously published fragments of Irmtraud Morgner's attempt to complete her ‘Salman trilogy’, may well be considered the last artefact of GDR literature, its ultimate postmodern manifestation, consisting of myriad voices, borrowings, allusions, parodies, bits of beginnings, and fragments of endings. It is also an angry document, which addresses abuses and deformations in the GDR and Morgner's own regret that her work had helped to sustain that state's political system. Yet here, too, myth and magic are invoked, not to offer an escape, but as a form of resistance, which she – in a clear allusion to Ernst Bloch – called ‘concrete utopia’. Like Thomas Mann in his Dr. Faustus, however, Morgner ‘takes back’ the fundamental optimism of her earlier works. If Morgner's famous Trobadora novel was written with faith in the ideology of a socialist utopia, Das heroische Testament clings to the possibility of ‘Heimat’ in something much more private and personal: the love of two human beings for one another.
Allegories of Cultural Relations: An Examination of Anne Duden's Mode of Reading Representations of St George and the Dragon
Authors: Ludden Teresa
Published: January 2004

This essay examines Anne Duden's literary‐philosophical text ‘Gegenstrebige Fügung’ in the light of Frankfurt School and feminist theories. It argues that Duden blurs the distinction between legend and myth in her writing about Vittore Carpaccio's paintings of St George and the Dragon to read the representation of the battle between man and dragon as illustrative of founding myths of Western Enlightenment culture. These include the emancipation of reason from nature, the belief in progress, and the privileging of mind and the autonomous subject over the object and matter. The essay examines Duden's mode of reading representations of the myth of the victory of good over evil as a disingenuous narrative which covers up what such representations actually produce: a discourse about normality and abnormality and about the types of selves, bodies and values which are privileged by Western culture. Duden's reading de‐mystifies traditional ways of interpreting St George's story in line with recent poststructuralist theory. However, rather than standard psychoanalytic readings of the story in which the dragon represents sexuality and femininity which needs to be repressed, I analyse Duden's more radical ‘Kulturkritik’ through her evocation of mechanisms of exclusion and the creation of binary oppositions as a prerequisite for the survival of culture and its myths and as a necessity for a repetition of culture's dominant narratives. The double sight that art allows, however, means that it functions in Duden's readings as a privileged realm where the forgotten and excluded may be remembered. Thus a reading against the grain becomes possible, activating alternative meanings.
Männermythos, Frauenmythos, und Danach? Anmerkungen Zum Mythos Ingeborg Bachmann
Authors: Albrecht Monika
Published: January 2004

Der Essay setzt sich kritisch mit zwei Aspekten des gegenwärtigen Bachmann‐Bildes auseinander, mit der Rückkehr des ‘Männermythos’ Ingeborg Bachmann in der literarischen Öffentlichkeit und mit der Fortschreibung des feministischen Bachmann‐Mythos in der deutschen Literaturwissenschaft. Zunächst zeigt ein Blick auf das Bachmann‐Bild in der neueren Zeitungskritik, dass dort inzwischen wieder präfeministische Vorstellungen und Klischees reaktiviert werden, die den Bachmann‐Mythos der 1950er Jahre im neuen Gewand des ausgehenden 20. Jahrhunderts auferstehen lassen. Aber auch das Bachmann‐Bild der feministischen Literaturwissenschaft hat sich noch nicht von Konstruktionen der 1980er Jahre gelöst, vor allem insofern, als nach wie vor an der Vorstellung von Bachmann als einer feministischen Vordenkerin festgehalten wird. Damals galt die Schreibweise der Autorin als vorweggenommene Konkretisierung poststrukturalistischer Thesen, heute werden ebenfalls wieder die neuesten geistes‐ und kulturwissenschaftlichen Errungenschaften in ihre Texte hineingelesen. Demgegenüber wird im folgenden darauf bestanden, daß es, will man Bachmann mit neueren Gender‐Theorien in Verbindung bringen, keineswegs ausreicht, wenn ihre Texte die herrschenden Geschlechterverhältnisse kritisch in Frage stellen. Auch wenn Bachmann die Frage der Geschlechtsidentität zunehmend beschäftigt hat: den radikalen Gedankenschritt, der in der Verabschiedung von essentialistischen Begriffen von Geschlechtsidentität besteht, hat die Autorin noch nicht vollzogen. Der folgende Essay versteht sich also als Plädoyer dafür, die Leistungen, aber auch die Grenzen von Bachmanns Texten im Horizont ihrer historischen und gesellschaftlichen Bedingtheit zu sehen – und nicht zuletzt die Macht der Geschlechtermythen ihrer Zeit ernst nehmen.
Mutual expectations: a study of the three‐way relationship between employment agencies, their client organisations and white‐collar agency ‘temps’
Authors: Druker Janet , Stanworth Celia
Published: January 2004

This paper examines the mutual expectations of employment agencies, the temporary workers who are placed by them and the client or host companies with whom they are placed. It considers the ambiguities and complexities inherent in the psychological contracts of agency temps, pointing to positive dimensions of the agency relationship with temps coupled with a tough transactional regime. In periods of uncertainty agency temping provided individuals with an illusion of freedom and control.
Building the New Europe: western and eastern roads to social partnership
Authors: Iankova Elena , Turner Lowell
Published: January 2004

This article focuses on the struggle for a social Europe by examining social partnership developments in two western countries, Germany and Britain, and two eastern countries, Bulgaria and Poland. The resurgence of social partnership in the west, even in the weakest case (Britain), is paradoxically driven in part by neoliberal EU economic policies. In the east, post‐communist tripartism helped preserve social peace with the coming of markets, while both international lending agencies and subsequent EU accession processes pushed domestic actors towards social dialogue. The coming or deepening of markets has therefore surprisingly promoted or reinforced relations of social partnership throughout Europe.
Wire Diffraction Gratings
Authors: Greenslade Thomas B.
Published: January 2004

In the summer of 1972, I attended the workshop on recreating classic experiments in physics at Barnard College.1 This was developed by Samuel Devons, and it was a defining experience that set me toward a research career involving early physics teaching apparatus. During the course of the workshop, I became curious about the original diffraction gratings developed by Fraunhofer and built a wire diffraction. A short note about the gratings was published in the American Journal of Physics the next year.2
Centrifugal Icicles and an Inertial Paradox
Authors: Collins Donald F.
Published: January 2004

During an ice storm, freezing rain fell on a rapidly rotating toy windmill during very windy conditions. As the water froze on the perimeter of the spinning wheel, it formed unusual icicles radiating outward from the perimeter of the wheel (Fig. 1). These centrifugal icicles are easy to understand from a conceptual standpoint — the freezing water drops are forced outward from the center by the centrifugal force, analogous to the sediment in a centrifuge tube. However, explanations from an inertial perspective prove to be very difficult, especially if one is reminded of the tendency of water drops to follow tangential trajectories when the water breaks away from a spinning wheel (see Fig. 2).
Detecting Infrared Radiation with a Phototransistor and an IR Filter
Authors: Lee Edward V.
Published: January 2004

This paper presents experiments to detect infrared radiation (IR).1 The key materials, which are readily available, are the following:

» A phototransistor detector, whose circuit diagram is shown in Fig. 1. The response of the phototransistor, which extends into the near infrared, is shown in Fig. 2, along with the response of the human eye.

» An inexpensive infrared filter2,3 — a piece of unexposed, processed Ektachrome® film, which absorbs visible light but transmits infrared.
Rollover of Sport Utility Vehicles
Authors: Penny Desmond N.
Published: January 2004

Recently, the PBS program “Frontline”1 examined the history of the development of the sport utility vehicle (SUV) and the efforts to force car makers to design SUVs that are less prone to rollover. The dangers of SUV rollovers were spotlighted in the fall of 2000, when the Ford-Firestone scandal prompted Congress to launch a series of hearings focusing on deaths and injuries related to faulty Firestone tires mounted on Ford Explorers. However, during the same 10-year period in which Ford-Firestone rollover crashes caused some 300 deaths, more than 12,000 people — 40 times as many — died in SUV rollovers unrelated to tire failure.1
Physics in East Timor
Authors: Gabrielson Curt
Published: January 2004

I recently returned from two years in East Timor, the world's newest nation. There I worked with teachers to develop the national physics curriculum for middle and high schools, taught at the national university (UNTIL), and trained teachers across the half-island. Here I'll share some of my successes and a few of the activities we developed, especially as related to the local culture and tropical environment.
Johannes Kepler and Extra Dimensions
Authors: Hendry Archibald W.
Published: January 2004

How many dimensions are there? The answer used to be four — three spatial and one time dimension. Maybe it still is, though nowadays we hear that the answer may be more, perhaps many more. Many of our students have heard about this on television or read about it. They want to know more. Why do physicists think we need more than three spatial dimensions? What's the point of it all?
Energy Flow Diagrams for Teaching Physics Concepts
Authors: Hobson Art
Published: January 2004

Energy is arguably the central unifying concept in physics. The validity of the principles of energy extends almost without change from “classical” physics through all of modern physics. Even processes that are too complex or too far outside the Newtonian regime to be easily described in terms of forces can be described in an accurate and conceptually transparent manner in terms of energy. Thus, energy is a useful central organizing principle in teaching physics conceptually. Every physical process is an energy transformation of some forms of energy into other forms. “Energy flow diagrams” present these transformations visually and approximately quantitatively.1 Even for complex processes where analysis in terms of force and motion would be out of the question, energy flow diagrams show the physical fundamentals in a meaningful manner. This paper discusses energy flow diagrams for a few simple processes, and proceeds to complex socially significant processes.
Hooray for Wrong Answers!
Authors: Payne Mark M.
Published: January 2004

Mark Payne is a member of Newark Abbey, a Benedictine monastery that sponsors St. Benedict's Preparatory School in Newark, New Jersey. After graduating from the University of Notre Dame in physics (1973), the Rev. Payne spent two years at Columbia University for a master's in physics (1975) and has been teaching introductory physics at St. Benedict's for 28 years. He encourages teachers to explore the explanations students offer when their answers are not what the teacher expected.
In Vivo Expression of the Mannose-Resistant Fimbriae of
Photorhabdus temperata
K122 during Insect Infection
Authors: Meslet-Cladiere L. M. , Pimenta A. , Duchaud E. , Holland I. B. , Blight M. A.
Published: January 2004

Photorhabdus temperata
K122 is an entomopathogenic bacterium symbiotically associated with nematodes of the family
Heterorhabditidae
. Surface fimbriae are important for the colonization of many pathogenic bacteria, and here we report the nucleotide sequence and analysis of the expression of a 12-kbp fragment encoding the mannose-resistant fimbriae of
P. temperata
(
mrf
). The
mrf
gene cluster contains 11 genes with an organization similar to that of the
mrp
locus from
Proteus mirabilis. mrfI
(encoding a putative recombinase) and
mrfA
(encoding pilin), the first gene in an apparent operon of nine other genes, are expressed from divergent promoters. The
mrfI
-
mrfA
intergenic region contains inverted repeats flanking the
mrfA
promoter. This region was shown to be capable of inversion, consistent with an ON/OFF regulation of the operon. In in vitro liquid cultures, both orientations were detected. Nevertheless, when we analyzed the expression of all of the genes in the
mrf
locus by semiquantitative reverse transcription-PCR during infection of
Galleria mellonella
(greater wax moth) larvae, expression of
mrfA
was not detected until 25 h postinfection, preceding the death of the larvae at 32 h. In contrast,
mrfJ
(a putative inhibitor of flagellar synthesis) was expressed throughout infection. Expression of
mrfI
was also detected only late in infection (25 to 30 h), indicating a possible increase in inversion frequency at this stage. In both in vitro liquid cultures and in vivo larval infections, the distal genes of the operon were expressed at substantially lower levels than
mrfA
. These results indicate the complex regulation of the
mrf
cluster during infection.
A Novel Evolutionary Lineage of Carbonic Anhydrase (ε Class) Is a Component of the Carboxysome Shell
Authors: So Anthony K.-C. , Espie George S. , Williams Eric B. , Shively Jessup M. , Heinhorst Sabine , Cannon Gordon C.
Published: January 2004

A significant portion of the total carbon fixed in the biosphere is attributed to the autotrophic metabolism of prokaryotes. In cyanobacteria and many chemolithoautotrophic bacteria, CO
2
fixation is catalyzed by ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), most if not all of which is packaged in protein microcompartments called carboxysomes. These structures play an integral role in a cellular CO
2
-concentrating mechanism and are essential components for autotrophic growth. Here we report that the carboxysomal shell protein, CsoS3, from
Halothiobacillus neapolitanus
is a novel carbonic anhydrase (ε-class CA) that has an evolutionary lineage distinct from those previously recognized in animals, plants, and other prokaryotes. Functional CAs encoded by
csoS3
homologues were also identified in the cyanobacteria
Prochlorococcus
sp. and
Synechococcus
sp., which dominate the oligotrophic oceans and are major contributors to primary productivity. The location of the carboxysomal CA in the shell suggests that it could supply the active sites of RuBisCO in the carboxysome with the high concentrations of CO
2
necessary for optimal RuBisCO activity and efficient carbon fixation in these prokaryotes, which are important contributors to the global carbon cycle.
Reversible Acyl-Homoserine Lactone Binding to Purified
Vibrio fischeri
LuxR Protein
Authors: Urbanowski M. L. , Lostroh C. P. , Greenberg E. P.
Published: January 2004

The
Vibrio fischeri
LuxR protein is the founding member of a family of acyl-homoserine lactone-responsive quorum-sensing transcription factors. Previous genetic evidence indicates that in the presence of its quorum-sensing signal,
N
-(3-oxohexanoyl) homoserine lactone (3OC6-HSL), LuxR binds to
lux
box DNA within the promoter region of the
luxI
gene and activates transcription of the
luxICDABEG
luminescence operon. We have purified LuxR from recombinant
Escherichia coli
. Purified LuxR binds specifically and with high affinity to DNA containing a
lux
box. This binding requires addition of 3OC6-HSL to the assay reactions, presumably forming a LuxR-3OC6-HSL complex. When bound to the
lux
box at the
luxI
promoter in vitro, LuxR-3OC6-HSL enables
E. coli
RNA polymerase to initiate transcription from the
luxI
promoter. Unlike the well-characterized LuxR homolog TraR in complex with its signal (3-oxo-octanoyl-HSL), the LuxR-30C6-HSL complex can be reversibly inactivated by dilution, suggesting that 3OC6-HSL in the complex is not tightly bound and is in equilibrium with the bulk solvent. Thus, although LuxR and TraR both bind 3-oxoacyl-HSLs, the binding is qualitatively different. The differences have implications for the ways in which these proteins respond to decreases in signal concentrations or rapid drops in population density.
The
Streptococcus gordonii
Platelet BindingProtein GspB Undergoes Glycosylation Independently ofExport
Authors: Bensing Barbara A. , Gibson Bradford W. , Sullam Paul M.
Published: January 2004

The
binding of bacteria and platelets may play a central role in the
pathogenesis of infective endocarditis. Platelet binding by
Streptococcus gordonii
strain M99 is predominantly mediated by
the 286-kDa cell wall-anchored protein GspB. This unusually large
protein lacks a typical amino-terminal signal peptide and is
translocated from the cytoplasm via a dedicated transport system. A
14-kb segment just downstream of
gspB
encodes SecA2 and SecY2,
two components of the GspB-specific transport system. The downstream
segment also encodes several putative glycosyl transferases that may be
responsible for the posttranslational modification of GspB. In this
study, we compared the abilities of M99 and two
GspB
−
mutant strains to bind various
lectins. GspB was found to have affinity for lectins that bind
N
-acetylglucosamine. We also examined variant forms of GspB
that lack a carboxy-terminal cell wall-anchoring domain and thus are
free of covalent linkage to cell wall peptidoglycan. Like native GspB,
these truncated proteins appear to be heavily glycosylated, as
evidenced by migration during sodium dodecyl sulfate-polyacrylamide gel
electrophoresis with an apparent molecular mass >100 kDa in
excess of the predicted mass, negligible staining with conventional
protein stains, and reactivity with hydrazide following periodate
oxidation. Furthermore, analysis of the carbohydrate associated with
the GspB variants by high-pH anion-exchange chromatography revealed the
presence of ∼70 to 100 monosaccharide residues per GspB
polypeptide (primarily
N
-acetylglucosamine and glucose).
Analysis of GspB in protoplasts of s
ecA2
or
secY2
mutant strains, which do not export GspB, indicates that GspB is
glycosylated in the cytoplasm of these strains. The combined data
suggest that the native GspB is a glycoprotein and that it may be
glycosylated prior to
export.
Nine Mutants of
Chlorobium tepidum
Each Unable To Synthesize a Different Chlorosome Protein Still Assemble Functional Chlorosomes
Authors: Frigaard Niels-Ulrik , Li Hui , Milks Kirstin J. , Bryant Donald A.
Published: January 2004

Chlorosomes of the green sulfur bacterium
Chlorobium tepidum
comprise mostly bacteriochlorophyll
c
(BChl
c
), small amounts of BChl
a
, carotenoids, and quinones surrounded by a lipid-protein envelope. These structures contain 10 different protein species (CsmA, CsmB, CsmC, CsmD, CsmE, CsmF, CsmH, CsmI, CsmJ, and CsmX) but contain relatively little total protein compared to other photosynthetic antenna complexes. Except for CsmA, which has been suggested to bind BChl
a
, the functions of the chlorosome proteins are not known. Nine mutants in which a single
csm
gene was inactivated were created; these mutants included genes encoding all chlorosome proteins except CsmA. All mutants had BChl
c
contents similar to that of the wild-type strain and had growth rates indistinguishable from or within ∼90% (CsmC
−
and CsmJ
−
) of those of the wild-type strain. Chlorosomes isolated from the mutants lacked only the protein whose gene had been inactivated and were generally similar to those from the wild-type strain with respect to size, shape, and BChl
c
, BChl
a
, and carotenoid contents. However, chlorosomes from the
csmC
mutant were about 25% shorter than those from the wild-type strain, and the BChl
c
absorbance maximum was blue-shifted about 8 nm, indicating that the structure of the BChl
c
aggregates in these chlorosomes is altered. The results of the present study establish that, except with CsmA, when the known chlorosome proteins are eliminated individually, none of them are essential for the biogenesis, light harvesting, or structural organization of BChl
c
and BChl
a
within the chlorosome. These results demonstrate that chlorosomes are remarkably robust structures that can tolerate considerable changes in protein composition.
Genetic Analysis of Disulfide Isomerization in
Escherichia coli
: Expression of DsbC Is Modulated by RNase E-Dependent mRNA Processing
Authors: Zhan Xiaoming , Gao Junjun , Jain Chaitanya , Cieslewicz Michael J. , Swartz James R. , Georgiou George
Published: January 2004

We designed a selection strategy for the isolation of
Escherichia coli
mutants exhibiting enhanced protein disulfide isomerase activity. The folding of a variant of tissue plasminogen activator (v-tPA), a protein containing nine disulfide bonds, in the bacterial periplasm is completely dependent on the level of disulfide isomerase activity of the cell. Mutations that increase this activity mediate the formation of catalytically active v-tPA, which in turn cleaves a
p
-aminobenzoic acid (PABA)-peptide adduct to release free PABA and thus allows the growth of an auxotrophic strain. Following chemical mutagenesis, a total of eight
E. coli
mutants exhibiting significantly higher disulfide isomerization activity, not only with v-tPA but also with two other unrelated protein substrates, were isolated. This phenotype resulted from significantly increased expression of the bacterial disulfide isomerase DsbC. In seven of the eight mutants, the upregulation of DsbC was found to be related to defects in RNA processing by RNase E, the
rne
gene product. Specifically, the genetic lesions in five mutants were shown to be allelic to
rne
, while an additional two mutants exhibited impaired RNase E activity due to lesions in other loci. The importance of mRNA stability on the expression of DsbC is underscored by the short half-life of the
dsbC
transcript, which was found to be only 0.8 min at 37°C in wild-type cells but was two- to threefold longer in some of the stronger mutants. These results (i) confirm the central role of DsbC in disulfide bond isomerization in the bacterial periplasm and (ii) suggest a critical role for RNase E in regulating DsbC expression.
Mutational Analysis of the
Myxococcus xanthus
Ω4400 Promoter Region Provides Insight into Developmental Gene Regulation by C Signaling
Authors: Yoder Deborah R. , Kroos Lee
Published: January 2004

Myxococcus xanthus
utilizes extracellular signals during development to coordinate cell movement, differentiation, and changes in gene expression. One of these signals, the C signal, regulates the expression of many genes, including Ω4400, a gene identified by an insertion of Tn
5 lac
into the chromosome. Expression of Tn
5 lac
Ω4400 is reduced in
csgA
mutant cells, which fail to perform C signaling, and the promoter region has several sequences similar to sequences found in the regulatory regions of other C-signal-dependent genes. One such gene, Ω4403, depends absolutely on the C signal for expression, and its promoter region has been characterized previously by mutational analysis. To determine if the similar sequences within the Ω4400 and Ω4403 regulatory regions function in the same way, deletion analysis and site-directed mutagenesis of the Ω4400 promoter region were performed. A 7-bp sequence centered at −49 bp, termed a C box, is identical in the Ω4400 and Ω4403 promoter regions, yet mutations in the individual base pairs affected expression from the two promoters very differently. Also, a single-base-pair change within a similar 5-bp element, which is centered at −61 bp in both promoter regions, had very different effects on the activities of the two promoters. Further mutational analysis showed that two regions are important for Ω4400 expression; one region, from −63 to −31 bp, is required for Ω4400 expression, and the other, from −86 to −81 bp, exerts a two- to fourfold effect on expression and is at least partially responsible for the C signal dependence of the Ω4400 promoter. Mutations in
sigD
and
sigE
, which are genes that encode σ factors, abolished and reduced Ω4400 expression, respectively. Expression of Ω4400 in
actB
or
actC
mutants correlated well with the altered levels of C signal produced in these mutants. Our results provide the first detailed analysis of an
M. xanthus
regulatory region that depends partially on C signaling for expression and indicate that similar DNA sequences in the Ω4400 and Ω4403 promoter regions function differently.
A Novel Putative Enterococcal Pathogenicity Island Linked to theespVirulence Gene ofEnterococcus faeciumand Associated with Epidemicity
Authors: Leavis Helen , Top Janetta , Shankar Nathan , Borgen Katrine , Bonten Marc , van Embden Jan , Willems Rob J. L.
Published: January 2004

Enterococcus faecalisharbors a virulence-associated surface protein encoded by theespgene. This gene has been shown to be part of a 150-kb putative pathogenicity island. A gene similar toesphas recently been found inEnterococcus faeciumisolates recovered from hospitalized patients. In the present study we analyzed the polymorphism in theespgene ofE. faecium, and we investigated the association ofespwith neighboring chromosomal genes. Theespgene showed considerable sequence heterogeneity in the regions encoding the nonrepeat N- and C-terminal domains of the Esp protein as well as differences in the number of repeats. DNA sequencing of chromosomal regions flanking theespgene ofE. faeciumrevealed seven open reading frames, representing putative genes implicated in virulence, regulation of transcription, and antibiotic resistance. These flanking regions were invariably associated with the presence or absence of theespgene inE. faecium, indicating thatespinE. faeciumis part of a distinct genetic element. Because of the presence of virulence genes in this gene cluster, the lower G+C content relative to that of the genome, and the presence ofespinE. faeciumisolates associated with nosocomial outbreaks and clinically documented infections, we conclude that this genetic element constitutes a putative pathogenicity island, the first one described inE. faecium. Except for the presence ofespandaraC, this pathogenicity island is completely different from theesp-containing pathogenicity island previously disclosed inE. faecalis.
ATP/ADP Translocases: a Common Feature of Obligate Intracellular Amoebal Symbionts Related to Chlamydiae and Rickettsiae
Authors: Schmitz-Esser Stephan , Linka Nicole , Collingro Astrid , Beier Cora L. , Neuhaus H. Ekkehard , Wagner Michael , Horn Matthias
Published: January 2004

ATP/ADP translocases catalyze the highly specific transport of ATP across a membrane in an exchange mode with ADP. Such unique transport proteins are employed by plant plastids and have among the prokaryotes so far only been identified in few obligate intracellular bacteria belonging to the
Chlamydiales
and the
Rickettsiales
. In this study, 12 phylogenetically diverse bacterial endosymbionts of free-living amoebae and paramecia were screened for the presence of genes encoding ATP/ADP transport proteins. The occurrence of ATP/ADP translocase genes was found to be restricted to endosymbionts related to rickettsiae and chlamydiae. We showed that the ATP/ADP transport protein of the
Parachlamydia
-related endosymbiont of
Acanthamoeba
sp. strain UWE25, a recently identified relative of the important human pathogens
Chlamydia trachomatis
and
Chlamydophila pneumoniae
, is functional when expressed in the heterologous host
Escherichia coli
and demonstrated the presence of transcripts during the chlamydial developmental cycle. These findings indicate that the interaction between
Parachlamydia
-related endosymbionts and their amoeba hosts concerns energy parasitism similar to the interaction between pathogenic chlamydiae and their human host cells. Phylogenetic analysis of all known ATP/ADP translocases indicated that the genes encoding ATP/ADP translocases originated from a chlamydial ancestor and were, after an ancient gene duplication, transferred horizontally to rickettsiae and plants.
Quorum Sensing-Controlled Biofilm Development in
Serratia liquefaciens
MG1
Authors: Labbate Maurizio , Queck Shu Yeong , Koh Kai Shyang , Rice Scott A. , Givskov Michael , Kjelleberg Staffan
Published: January 2004

Serratia liquefaciens
MG1 contains an
N-
acylhomoserine lactone-mediated quorum-sensing system that is known to regulate swarming motility colonization. In this study, we describe for
S. liquefaciens
MG1 the development of a novel biofilm consisting of cell aggregates and differentiated cell types, such as cell chains and long filamentous cells. Furthermore, quorum sensing is shown to be crucial for normal biofilm development and for elaborate differentiation. A mutant of
S. liquefaciens
MG1 that was incapable of synthesizing extracellular signal formed a thin and nonmature biofilm lacking cell aggregates and differentiated cell chains. Signal-based complementation of this mutant resulted in a biofilm with the wild-type architecture. Two quorum-sensing-regulated genes (
bsmA
and
bsmB
) involved in biofilm development were identified, and we propose that these genes are engaged in fine-tuning the formation of cell aggregates at a specific point in biofilm development.
Regulation of IcsP, the Outer Membrane Protease of the
Shigella
Actin Tail Assembly Protein IcsA, by Virulence Plasmid Regulators VirF and VirB
Authors: Wing Helen J. , Yan Arthur W. , Goldman Seth R. , Goldberg Marcia B.
Published: January 2004

The
Shigella
outer membrane protease IcsP removes the actin assembly protein IcsA from the bacterial surface, and consequently modulates
Shigella
actin-based motility and cell-to-cell spread. Here, we demonstrate that IcsP expression is undetectable in mutants lacking either of two transcriptional activators, VirF and VirB. In wild-type
Shigella
spp.,
virB
expression is entirely dependent on VirF; therefore, to circumvent this regulatory cascade, we independently expressed VirF or VirB in
Shigella
strains lacking both activators and measured both IcsP levels and transcription from the
icsP
promoter. Our results show that VirB significantly enhanced
icsP
transcription, even in the absence of VirF. In contrast, when VirF was induced in the absence of VirB, VirF had variable effects. The regulation of
icsP
is distinctly different from the regulation of the gene encoding its major substrate,
icsA
, which is activated by VirF and not VirB. We propose that the different pathways regulating
icsA
and
icsP
may be critical to the modulation of IcsA-mediated actin-based motility by IcsP.
The NeuC Protein ofEscherichia coliK1 Is a UDPN-Acetylglucosamine 2-Epimerase
Authors: Vann Willie F. , Daines Dayle A. , Murkin Andrew S. , Tanner Martin E. , Chaffin Donald O. , Rubens Craig E. , Vionnet Justine , Silver Richard P.
Published: January 2004

The K1 capsule is an essential virulence determinant ofEscherichia colistrains that cause meningitis in neonates. Biosynthesis and transport of the capsule, an α-2,8-linked polymer of sialic acid, are encoded by the 17-kbkpsgene cluster. We deletedneuC, a K1 gene implicated in sialic acid synthesis, from the chromosome of EV36, a K-12-K1 hybrid, by allelic exchange. Exogenously added sialic acid restored capsule expression to the deletion strain (ΔneuC), confirming that NeuC is necessary for sialic acid synthesis. The deduced amino acid sequence of NeuC showed similarities to those of UDP-N-acetylglucosamine (GlcNAc) 2-epimerases from both prokaryotes and eukaryotes. The NeuC homologue from serotype IIIStreptococcus agalactiaecomplements ΔneuC. We cloned theneuCgene into an intein expression vector to facilitate purification. We demonstrated by paper chromatography that the purifiedneuCgene product catalyzed the formation of [2-14C]acetamidoglucal and [N-14C]acetylmannosamine (ManNAc) from UDP-[14C]GlcNAc. The formation of reaction intermediate 2-acetamidoglucal with the concomitant release of UDP was confirmed by proton and phosphorus nuclear magnetic resonance spectroscopy. NeuC could not use GlcNAc as a substrate. These data suggest thatneuCencodes an epimerase that catalyzes the formation of ManNAc from UDP-GlcNAc via a 2-acetamidoglucal intermediate. The unexpected release of the glucal intermediate and the extremely low rate of ManNAc formation likely were a result of the in vitro assay conditions, in which a key regulatory molecule or protein was absent.
The Lactococcal Abortive Phage Infection System AbiP Prevents both Phage DNA Replication and Temporal Transcription Switch
Authors: Domingues Susana , Chopin Alain , Ehrlich S. Dusko , Chopin Marie-Christine
Published: January 2004

We describe here a new lactococcal abortive phage infection system, designated AbiP. AbiP is effective against some lactococcal phages of one prevalent group, 936, but not against phages from the other two groups (c6A and P335). It was identified in theLactococcus lactissubsp.cremorisstrain IL420, on the native plasmid pIL2614. AbiP is encoded by a single gene, expressed in an operon with a second gene. In this work,abiPis shown to affect both the replication and transcription of phage DNA. In AbiP+cells, phage DNA replication is arrested approximately 10 min after infection. Levels of middle and late phage transcripts are lower in AbiP+than in AbiP−cells, probably due to the smaller amount of phage DNA. By contrast, early phage transcripts are more abundant in AbiP+than in AbiP−cells, suggesting that the switch-off, which occurs 15 min after infection in AbiP−cells, is prevented in AbiP+cells.
Control of Glucose- and NaCl-Induced Biofilm Formation by
rbf
in
Staphylococcus aureus
Authors: Lim Yong , Jana Malabendu , Luong Thanh T. , Lee Chia Y.
Published: January 2004

Both
Staphylococcus aureus
and
S. epidermidis
are capable of forming biofilm on biomaterials. We used Tn
917
mutagenesis to identify a gene,
rbf
, affecting biofilm formation in
S. aureus
NCTC8325-4. Sequencing revealed that Rbf contained a consensus region signature of the AraC/XylS family of regulators, suggesting that Rbf is a transcriptional regulator. Insertional duplication inactivation of the
rbf
gene confirmed that the gene was involved in biofilm formation on polystyrene and glass. Phenotypic analysis of the wild type and the mutant suggested that the
rbf
gene mediates the biofilm formation of
S. aureus
at the multicellular aggregation stage rather than at initial attachment. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis demonstrated that the mutation resulted in the loss of an ∼190-kDa protein. Biofilm production by the mutant could be restored by complementation with a 2.5-kb DNA fragment containing the
rbf
gene. The
rbf
-specific mutation affected the induction of biofilm formation by glucose and a high concentration of NaCl but not by ethanol. The mutation did not affect the transcription of the
ica
genes previously shown to be required for biofilm formation. Taken together, our results suggest that the
rbf
gene is involved in the regulation of the multicellular aggregation step of
S. aureus
biofilm formation in response to glucose and salt and that this regulation may be mediated through the 190-kDa protein.
A Mutant Form of the
Neisseria gonorrhoeae
Pilus Secretin Protein PilQ Allows Increased Entry of Heme and Antimicrobial Compounds
Authors: Chen Ching-ju , Tobiason Deborah M. , Thomas Christopher E. , Shafer William M. , Seifert H. Steven , Sparling P. Frederick
Published: January 2004

A spontaneous point mutation in
pilQ
(
pilQ1
) resulted in phenotypic suppression of a hemoglobin (Hb) receptor mutant (
hpuAB
mutant), allowing gonococci to grow on Hb as the sole source of iron. PilQ, formerly designated OMP-MC, is a member of the secretin family of proteins located in the outer membrane and is required for pilus biogenesis. The
pilQ1
mutant also showed decreased piliation and transformation efficiency. Insertional inactivation of
pilQ1
resulted in the loss of the Hb utilization phenotype and decreased entry of free heme. Despite the ability of the
pilQ1
mutant to use Hb for iron acquisition and porphyrin, there was no demonstrable binding of Hb to the cell surface. The
pilQ1
mutant was more sensitive to the toxic effect of free heme in growth medium and hypersensitive to the detergent Triton X-100 and multiple antibiotics. Double mutation in
pilQ1
and
tonB
had no effect on these phenotypes, but a double
pilQ1 pilT
mutant showed a reduction in Hb-dependent growth and decreased sensitivity to heme and various antimicrobial agents. Insertional inactivation of wild-type
pilQ
also resulted in reduced entry of heme, Triton X-100, and some antibiotics. These results show that PilQ forms a channel that allows entry of heme and certain antimicrobial compounds and that a gain-of function point mutation in
pilQ
results in TonB-independent, PilT-dependent increase of entry.
Rhodobacter capsulatus nifA1
Promoter: High-GC −10 Regions in High-GC Bacteria and the Basis for Their Transcription
Authors: Richard Cynthia L. , Tandon Animesh , Kranz Robert G.
Published: January 2004

It was previously shown that the
Rhodobacter capsulatus
NtrC enhancer-binding protein activates the
R. capsulatus
housekeeping RNA polymerase but not the
Escherichia coli
RNA polymerase at the
nifA1
promoter. We have tested the hypothesis that this activity is due to the high G+C content of the −10 sequence. A comparative analysis of
R. capsulatus
and other α-proteobacterial promoters with known transcription start sites suggests that the G+C content of the −10 region is higher than that for
E. coli
. Both in vivo and in vitro results obtained with
nifA1
promoters with −10 and/or −35 variations are reported here. A major conclusion of this study is that α-proteobacteria have evolved a promiscuous sigma factor and core RNA polymerase that can transcribe promoters with high-GC −10 regions in addition to the classic
E. coli
Pribnow box. To facilitate studies of
R. capsulatus
transcription, we cloned and overexpressed all of the RNA polymerase subunits in
E. coli
, and these were reconstituted in vitro to form an active, recombinant
R. capsulatus
RNA polymerase with properties mimicking those of the natural polymerase. Thus, no additional factors from
R. capsulatus
are necessary for the recognition of high-GC promoters or for activation by
R. capsulatus
NtrC. The addition of
R. capsulatus
σ
70
to the
E. coli
core RNA polymerase or the use of −10 promoter mutants did not facilitate
R. capsulatus
NtrC activation of the
nifA1
promoter by the
E. coli
RNA polymerase. Thus, an additional barrier to activation by
R. capsulatus
NtrC exists, probably a lack of the proper
R. capsulatus
NtrC-
E. coli
RNA polymerase (protein-protein) interaction(s).
The RecA Protein ofHelicobacter pyloriRequires a Posttranslational Modification for Full Activity
Authors: Fischer Wolfgang , Haas Rainer
Published: January 2004

The RecA protein is a central component of the homologous recombination machinery and of the SOS system in most bacteria. In performing these functions, it is involved in DNA repair processes and plays an important role in natural transformation competence. This may be especially important inHelicobacter pylori, where an unusually high degree of microdiversity among strains is generated by homologous recombination. We have suggested previously that theH. pyloriRecA protein is subject to posttranslational modifications that result in a slight shift in its electrophoretic mobility. Here we show that at least two genes downstream ofrecAare involved in this modification and that this process is dependent on genes involved in glycosylation and lipopolysaccharide biosynthesis. Site-directed mutagenesis of a putative glycosylation site results in production of an unmodified RecA protein. This posttranslational modification is not involved in membrane targeting or cell division functions but is necessary for the full function of RecA in DNA repair. Thus, it might be an adaptation to the specific requirements ofH. pyloriin its natural environment.
A Predicted ABC Transporter, FtsEX, Is Needed for Cell Division in
Escherichia coli
Authors: Schmidt Kari L. , Peterson Nicholas D. , Kustusch Ryan J. , Wissel Mark C. , Graham Becky , Phillips Gregory J. , Weiss David S.
Published: January 2004

FtsE and FtsX have homology to the ABC transporter superfamily of proteins and appear to be widely conserved among bacteria. Early work implicated FtsEX in cell division in
Escherichia coli
, but this was subsequently challenged, in part because the division defects in
ftsEX
mutants are often salt remedial. Strain RG60 has an
ftsE
::
kan
null mutation that is polar onto
ftsX
. RG60 is mildly filamentous when grown in standard Luria-Bertani medium (LB), which contains 1% NaCl, but upon shift to LB with no NaCl growth and division stop. We found that FtsN localizes to potential division sites, albeit poorly, in RG60 grown in LB with 1% NaCl. We also found that in wild-type
E. coli
both FtsE and FtsX localize to the division site. Localization of FtsX was studied in detail and appeared to require FtsZ, FtsA, and ZipA, but not the downstream division proteins FtsK, FtsQ, FtsL, and FtsI. Consistent with this, in media lacking salt, FtsA and ZipA localized independently of FtsEX, but the downstream proteins did not. Finally, in the absence of salt, cells depleted of FtsEX stopped dividing before any change in growth rate (mass increase) was apparent. We conclude that FtsEX participates directly in the process of cell division and is important for assembly or stability of the septal ring, especially in salt-free media.
Reduced Transaminase B (IlvE) Activity Caused by the Lack ofyjgFIs Dependent on the Status of Threonine Deaminase (IlvA) inSalmonella entericaSerovar Typhimurium
Authors: Schmitz George , Downs Diana M.
Published: January 2004

The YjgF/YER057c/UK114 family is a highly conserved class of proteins that is represented in the three domains of life. Thus far, a biochemical function demonstrated for these proteins in vivo or in vitro has yet to be defined. In several organisms, strains lacking a YjgF homolog have a defect in branched-chain amino acid biosynthesis. This study probes the connection betweenyjgFand isoleucine biosynthesis inSalmonella enterica.In strains lackingyjgFthe specific activity of transaminase B, catalyzing the last step in the synthesis of isoleucine, was reduced. In the absence ofyjgF, transaminase B activity could be restored by inhibiting threonine deaminase, the first enzymatic step in isoleucine biosynthesis. Strains lackingyjgFshowed an increased sensitivity to sulfometruron methyl, a potent inhibitor of acetolactate synthase. Based on work described here and structural reports in the literature, we suggest a working model in which YjgF has a role in protecting the cell from toxic effects of imbalanced ketoacid pools.
The
trans
-Acting Protein Interacting with the DNA Motif Proximal to the Transcriptional Start Site of Plant
l
-Asparaginase Is Bacterial Sarcosine Oxidase
Authors: Jones William T. , Al-Samarrai Taha , Reeves Janice M. , Ryan Gordon B. , Kirk Christopher A. , Vincze Eva , Harvey Dawn , McCambridge Marie , Greenwood David , Reynolds Paul H. S.
Published: January 2004

A
trans
-acting protein interacting with a specific sequence motif proximal to the transcriptional start site of the
l
-asparaginase promoter has been observed previously (E. Vincze, J. M. Reeves, E. Lamping, K. J. F. Farnden, and P. H. S. Reynolds, Plant Mol. Biol. 26:303-311, 1994). Gel retardation experiments in which protein extracts of
Mesorhizobium loti
and developing nodules were used suggested a bacterial origin for the repressor binding protein (
rep2037
). Nodulation tests were performed by using different Fix
−
Tn
5
mutants of
M. loti.
Analyses of these mutants revealed a correlation between the presence of
Mesorhizobium
in the nodule-like structures and the ability of nodule protein extracts to bind the repressor binding domain (RBD). Through the use of mutated RBD sequences, the RBD sequence was identified as CTAAAAT. The repressor protein was isolated from
M. loti
NZP2037 by multiple chromatographic procedures and affinity separation by using concatemers of RBD attached to magnetic beads. Sequencing of the recovered protein resulted in identification of the repressor protein as the sarcosine oxidase α subunit. This was confirmed by expression of the gene encoding the
M. loti
α subunit of sarcosine oxidase in
Escherichia coli.
When the expressed peptide was bound to RBD, the gel retardation result was identical to the result obtained with
rep2037
from
M. loti
strain NZP2037.