bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustic signal recovery by thermal demodulation
Authors: Boullosa R. R. , Santillán Arturo O.
Published: October 2006

One operating mode of recently developed thermoacoustic transducers is as an audio speaker that uses an input superimposed on a direct current; as a result, the audio signal occurs at the same frequency as the input signal. To extend the potential applications of these kinds of sources, the authors propose an alternative driving mode in which a simple thermoacoustic device, consisting of a metal film over a substrate and a heat sink, is excited with a high frequency sinusoid that is amplitude modulated by a lower frequency signal. They show that the modulating signal is recovered in the radiated waves due to a mechanism that is inherent to this type of thermoacoustic process. If the frequency of the carrier is higher than 30kHz and any modulating signal (the one of interest) is in the audio frequency range, only this signal will be heard. Thus, the thermoacoustic device operates as an audio-band, self-demodulating speaker.
A history of Japanese dermatology: Past, present and future
Authors: NISHIKAWA Takeji
Published: October 2006

On the occasion of the 14th Korea–Japan joint meeting of dermatology, the founding of the Japanese Dermatological Association, its activities and relationship to neighboring societies were presented to let both Korean and Japanese participants know the current status of Japanese dermatology. It is felt that one central meeting in Asia will be necessary to make a strong impact on not only Asian but also Western colleagues. We should make more of an effort to get used to our common international language, English, so that we can communicate with other Asian colleagues more closely and in more depth in this era of increasing globalization.
The influence of reduced flow during a drought on patterns of variation in macroinvertebrate assemblages across a spatial hierarchy in two lowland rivers
Authors: LIND P. R. , ROBSON B. J. , MITCHELL B. D.
Published: October 2006

1. With the aim of determining whether patterns of variation in macroinvertebrate assemblage composition across the hierarchy of spatial units in two lowland rivers changed during a supra‐seasonal drought (1997–2000), patterns during a reduced flow season (1999–2000) were compared with those during two preceding higher flow seasons (1997–98 and 1998–99) using samples from the Glenelg and Wimmera Rivers, two lowland regulated rivers in western Victoria, Australia.

2. We hypothesised that (i) differences between reaches would increase during the reduced flow season owing to decreased hydrological connectivity, (ii) differences between the habitats would decrease because the cessation of flow in run habitats should cause them to become more similar to pool habitats and (iii) differences between microhabitats would also decrease because of reduced scour of inorganic substrata and large woody debris.

3. During each season, macroinvertebrates were sampled from three microhabitats (sand/silt substratum, large woody debris and macrophytes) that were hierarchically nested within a run or pool habitat and within one of three reaches within each river. A range of physico‐chemical variables was also sampled.

4. Analysis of similarity showed that assemblage composition in both rivers during the higher flow seasons differed more among microhabitats than other spatial units. However, during the reduced flow season, assemblage composition in the Wimmera River differed most among reaches. This change in pattern was associated with the combined effects of decreased flow and longitudinal increases in salinity. In contrast, the fauna of the Glenelg River appeared to be resistant to the effects of the reduced flow season, owing to limited decline in water quality despite lower river discharge.

5. As salinisation and poor water quality in the Wimmera River result from human activities in the catchment, these results support the idea that human impacts on rivers can change macroinvertebrate scaling patterns and exacerbate the effects of drought beyond the tolerance of many riverine macroinvertebrates.
Proteomic analyses of male contributions to honey bee sperm storage and mating
Authors: Collins A. M. , Caperna T. J. , Williams V. , Garrett W. M. , Evans J. D.
Published: October 2006

Honey bee (Apis mellifera L.) queens mate early in life and store sperm for years. Male bees likely contribute significantly to sperm survival. Proteins were extracted from seminal vesicles and semen of mature drones, separated by electrophoresis, and analysed by peptide mass fingerprinting. Computer searches against three databases, general species, honey bees and fruit flies, were performed. Spectra were used to query the recently generated honey bee genome protein list as well as general species and fruit fly databases. Of the 69 unique honey bee proteins found, 66 are also in Drosophila melanogaster. Two proteins only matched honey bee genes and one is a widespread protein lost from the fly genome. There is over‐representation of genes implicated in the glycolysis pathway. Metabolism‐associated proteins were found primarily in the seminal vesicle. Male accessory gland proteins as identified in Drosophila rarely had orthologs among proteins found in the honey bee. A complete listing of gel spots chosen including honey bee genome matches and Mascot searches of MALDI‐TOF results with statistics is in the Supplementary table. MALDI‐TOF spectra and more complete Mascot peptide mass fingerprinting data are available on request. Supplementary figs 1–3 show the stained protein gels.
Antimicrobial Effects of Lactoferrin, Lysozyme, and the Lactoperoxidase System and Edible Whey Protein Films Incorporating the Lactoperoxidase System Against Salmonella enterica and Escherichia coli O157:H7
Authors: Min Seacheol , Harris Linda J. , Krochta John M.
Published: October 2006

Lactoferrin (LF), lysozyme (LZ), the lactoperoxidase system (LPOS), and edible whey protein isolate (WPI) films incorporating LPOS were studied for inhibition of Salmonella enterica and Escherichia coli O157:H7. Antimicrobial effects of LF (5 to 40 mg/mL), LZ (1 to 20 mg/mL), and LPOS (0.5% to 5.0% [w/v] [0.03–.25 g/g, dry basis]) were examined by measuring turbidity of antimicrobial‐containing media after inoculation and by examining cell inhibition by WPI films incorporating LPOS (LPOS‐WPI films) on an agar recovery medium. Elastic modulus (EM), tensile strength (TS), percent elongation (%E), oxygen permeability (OP), and Hunter L, a and b of WPI films incorporating 0.03 to 0.25 g/g of LPOS were compared with those of plain WPI films without LPOS. The growth of S. enterica and E. coli O157:H7 (4 log colony‐forming units [CFU]/mL) in tryptic soy broth (TSB) was not prevented by LF at ≥20 and ≥40 mg/mL, respectively. S. enterica and E. coli O157:H7 in TSB were not inhibited by LZ at ≥ 6 and ≥ 20 mg/mL, respectively. LPOS at concentrations of 2.75% (w/v) and 1.0% (w/v) reduced S. enterica and E. coli O157:H7 to below the limit of detection (1 CFU/mL) in TSB, respectively. LPOS‐WPI films (0.15 g/g) completely inhibited S. enterica and E. coli O157:H7 (4 log CFU/cm2), inoculated either onto agar before placing the film disc or onto top of the film disc. Incorporation of 0.25 g/g of LPOS decreased EM, TS, and %E. The oxygen barrier property of WPI films was improved with the incorporation of LPOS at 0.15 to 0.25 g/g.
Enhanced Thermal Resistance of Salmonella in Whole Muscle Compared to Ground Beef
Authors: Orta‐Ramirez Alicia , Marks Bradley P. , Warsow Christopher R. , Booren Alden M. , Ryser Elliot T.
Published: October 2006

Irradiated beef (whole ‐muscle and ground product with identical fat, protein, and moisture composition) was exposed to a Salmonella‐ inoculated marinade and heated in brass tubes in a water bath at 55 °C, 60 °C, and 62.5 °C. The bacterial load and thermal lag time were similar (α= 0.05) for both whole and ground muscle; therefore, all samples had equivalent composition, inoculation levels, and thermal histories. Assuming 1st‐order kinetics, the inactivation rate constants (k values) in whole muscle were 50% lower than those in ground product at each temperature (P = 0.0001), and Arrhenius‐type models described the temperature dependency of k (R2 > 0.95). Because thermal processing regulations are generally based on ground product studies, thermal process validations for meat and poultry products may need to consider the physical state (whole ‐muscle versus ground) of the product being manufactured.
Heat shock 70 gene is differentially expressed in Histoplasma capsulatum strains with different levels of thermotolerance and pathogenicity
Authors: Caruso M. , Sacco M. , Medoff G. , Maresca B.
Published: October 2006

The response to heat shock has been examined In two strains of the dimorphic pathogenic fungus Histoplasma capsulatum, which differ considerably in thermotolerance and pathogenicity. The gene for the 70 kD heat shock protein (hsp70) was isolated using a Drosophila hsp70 gene to screen a cosmid library of the DNA from the temperature‐sensitive Downs strain (low level of thermotolerance for mice). Using the cloned gene as a probe, we have measured the transcription of the endogenous hsp70 gene at 25°C and in response to temperature shift to 34°, 37° and 40°C, temperatures that trigger the mycelial to yeast phase transition in this fungus. The gene is constitutively transcribed at low levels, both in the yeast and the mycelial stages. Synthesis of hsp70 mRNA was transiently increased 1 to 3 h after the temperature shifts. By Northern analysis, peak levels of transcription were shown to occur at 34°C in the Downs strain and at 37°C in the more pathogenic G222B strain. Our results are consistent with reports in which it has been shown that heat shock gene expression is part of temperature adaptation and probably developmental processes. The low levels of transcription of the hsp70 gene in the Downs strain at 37°C correlate with its greater temperature sensitivity and low level of virulence.
Nucleotide sequence, regulation and functional analysis of the papC gene required for cell surface localization of Pap pili of uropathogenic Escherichia coli
Authors: Norgren. M. , Bága. M. , Tennent J.M. , Normark S.
Published: October 2006

The papC gene of uropathogenic Escherichia coli is required for the formation of digalactoside‐binding Pap pili. papC forms part of an operon wherein the regulatory gene papS, the major pilin gene papA, a minor pilin‐like gene papH, and papC are co‐transcribed. Furthermore, the extent of PapC synthesis was found to affect the number of pili expressed on the cell surface. The DNA sequence of the papC gene is presented and its deduced amino acid sequence is compared to that of the FaeD protein encoded by the K88 pili gene cluster. The PapC protein was localized to the E. coli outer membrane where it may form a trans‐membrane channel through which pilin subunits are surface localized.
An E. coli promoter induced by the cessation of growth
Authors: Connell N. , Han Z. , Moreno F. , Kolter R.
Published: October 2006

The production of the bacterial DNA replication inhibitor Microcin B17 is induced as cultures enter stationary phase. Using SI nuclease protection assays we have shown that this induction is the result of increased levels of transcription initiation from a promoter located upstream from mcbA, the structural gene for Microcin B17. Upstream from the start site of transcription there is a rather typical ‐35 region. However, there is no good homology to the consensus –10 region. While most of the cell's transcription is shut off as a result of the cessation of growth, transcription from the mcbA promoter continues for several hours in stationary phase. A single‐copy gene fusion between mcbA and lacZ was used to monitor the response of the promoter to different nutritional conditions and in different host backgrounds altered in metabolic regulatory loci. Starvation for nitrogen, phosphate or carbon sources all induced transcription from the promoter. Levels of transcription were reduced in ompR backgrounds, in contrast, mutations in other global regulatory loci, fnr, relA and cya had little or no effect.
pWW174: A large plasmid from Acinetobacter calcoaceticus encoding benzene catabolism by the β‐ketoadipate pathway
Authors: Winstanley C. , Taylor S. C. , Williams P. A.
Published: October 2006

Acinetobacter calcoaceticus RJE74 contains a large transmissible catabolic plasmid, pWW174, of about 200 kb, which encodes its ability to grow on benzene (Bzn+). pWW174 was unstable in Acinetobacter hosts and was lost at high frequency in the absence of selection for Bzn*. The catabolic pathway appeared to be via benzene cis‐glycol, catechol and the β‐ketoadipate (ortho) pathway. pWW174 encodes a catechol 1,2‐oxygenase which is significantly more thermolabile than the chromosomally determined enzyme. pWW174 was able to complement all cat mutants (catechol to central metabolites) of A. calcoaceticus ADP1 (BD413) tested. Two regions of the plasmid were cloned, one carrying catA, the gene for catechol 1,2‐oxygenase, and another carrying catBCDE, the subsequent four enzymes of the β‐ketoadipate pathway: these two regions appeared to be separated by at least 10 kbp. Hybridization indicated homology between the plasmid cat genes and the corresponding chromosomal genes of ADPL.
Utilization of a mini‐mu transposon to construct defined mutants in Streptococcus mutans
Authors: Kuramltsu H. K.
Published: October 2006

The gtfB gene coding for glucosyltransferase‐l (GTF‐I) activity previously isolated from Streptococcus mutans GS–5 was insertionally inactivated with the newly constructed transposon MudE in an Escherichia coli background, insertion of MudE into various regions of the gtfB gene led to inactivation of GTF‐I activity. The altered gene was introduced back into S. mutans GS–5 by transformation and produced mutants defective in insoluble glucan synthesis as well as the ability to colonize smooth surfaces in the presence of sucrose. Therefore, the MudE transposon can be utilized to produce specific mutants in oral streptococci as well as in other transformable Gram‐positive bacteria expressing an erythromycin‐resistance marker.
Sensitivity of Escherichia coli to various β‐lactams is determined by the interplay of outer membrane permeability and degradation by periplasmic β‐lactamases: a quantitative predictive treatment
Authors: Nikaido H. , Normark S.
Published: October 2006

In Gram‐negative bacteria, β‐lactam antibiotics must overcome two barriers, the outer membrane and the periplasmic β‐lactamase, before they reach the targets of their action, penicillin‐binding proteins. Although the barrier property of the outer membrane and catalytic property of the β‐lactamases have been studied and their significance in creating β‐lactam resistance emphasized, the interaction between these two barriers has not been treated quantitatively. Such treatment shows that the sensitivity, to a variety of β‐lactams, of the Escherichia coli K‐12 cells containing very different levels of chromosomally coded AmpC β‐lactamase, or a plasmid‐coded TEM‐type β‐lactamase, can be predicted rather accurately from the penetration rate through the outer membrane and the hydrolysis rate in the periplasm. We further propose a new parameter,‘target access Index', which is a quantitative expression of the result of interaction between the two barriers, and reflects the probability of success for the antibiotic to reach the targets.
Activation of the lac Operon of Escherichia coli by a mutant FNR protein
Authors: Spiro S. , Guest J. R.
Published: October 2006

The FNR protein of E. coli is a transcriptional activator required for the expression of genes involved in anaerobic respiratory pathways. Site‐directed mutagenesis was used to alter three amino acids in the recognition helix of the putative DNA‐binding domain of FNR, with the aim of changing its specificity to that of the cyclic AMP receptor protein (CRP). in the presence of the mutant protein (FNR‐215) expression of the lac Operon was activated during anaerobiosis and unaffected by glucose. FNR‐215 did not have a uniform effect on the expression of other cAMP‐CRP‐dependent genes, but the results demonstrate the fundamental similarity between FNR‐ and CRP‐mediated transcriptional activation.
ParD: a new gene coding for a protein required for chromosome partitioning and septum localization in Escherichia coli
Authors: Hussain K. , Begg K. J. , Salmond G. P. C. , Donachie W. D.
Published: October 2006

A new gene, parD, has been located at 88.5 min on the genetic map of E. coli. Cells carrying an amber mutation in this gene, together with a temperature‐sensitive suppressor tRNA, are able to grow, synthesize DNA and divide at both 30°C and 42°C. At 42°C, however, they are defective both in the separation of replicated chromosomes and in the placement of septa. Both the amount of DNA and the number of septa per cell mass are normal in cells growing at 42°C: only the localization of the chromosomes and septa are altered. As a result, cells of random sizes are produced at 42°C and the smallest of these contain no DNA.
Molecular cloning and characterization of the beta‐amylase gene from Bacillus circulans
Authors: Siggens K. W.
Published: October 2006

A gene encoding the β‐amylase of Bacillus circulans was isolated from a lambda library and sequenced. The structural gene consists of a 1725 bp open reading frame encoding a polypeptide with a predicted molecular wt of 62830 Daltons. Two active forms of the enzyme were found when the gene was expressed In E. coli. The larger 60 kD form was approximately 3 kD larger than the mature β‐amylase secreted from B. circulans, suggesting that processing of this protein is different between the two species. The smaller 49 kD form is also present at a low level in B. circulans and may result from proteolytic cleavage. The enzyme has a temperature optimum of 50°C. Two other genes, one encoding an α‐amylase and one a pullulanase, were also isolated from the lambda library.
Isolation and sequence of the spoOE gene: its role in initiation of sporulation in Bacillus subtills
Authors: Perego M. , Hoch J. A.
Published: October 2006

The pleiotropic stage 0 sporulation focus spoOE was isolated and sequenced. The spo0E gene was found to code for a protein of 9791 molecular weight. Two Spo0E mutations were identified by sequence analysis and were found to give rise to nonsense codons within the gene. The results indicated that it is the lack of the spo0E gene product that is responsible for the sporulation‐defective phenotype. The DNA fragment containing the spo0E locus was inhibitory to sporulation when present on a multicopy plasmid. Since DNA fragments containing only the upstream region of the gene were also inhibitory, this effect was not due to over‐production of the spoOE gene product. Coupling the transcription of the spoOE gene to 3‐galactosidase in an integrative plasmid vector revealed that active transcription of this gene begins at the end of exponential growth and continues through the early part of sporulation. Studies of the regulation of this gene have allowed the generation of a hypothesis to explain the interactions of those five stage 0 genes involved in the activation of sporulation‐specific transcription.
The ParD‐ mutant of Escherichia coli also carries Aam mutation. The complete sequence of gyrA
Authors: Hussain K. , Elliott E. J. , Salmond G. P. C.
Published: October 2006

The phenotype of a recently‐described mutant (OVG), conditionally defective in chromosome partitioning and septal positioning, was originally thought to be due to a new gene (parD) mapping at 88.4 min. We have now shown that, in addition to the parD mutation, OV6 carries a gyrAam mutation and that this mutation is probably responsible for the gross phenotype of the mutant. We have cloned the gyrA gene, identified the GyrA protein, sequenced the gyrA gene and flanking genes, cloned and sequenced the gyrAam, mutation, and identified its truncated product, in addition, we have identified the transcriptional start point of the gyrA gene. The E. coli GyrA protein has extensive homologies with Gyrase proteins of other organisms and weak sequence homologies with some eukaryotic cytoskeletal proteins.
Regulatory circuits controlling transcription of TOL plasmid operon encoding meta‐cleavage pathway for degradation of alkylbenzoates by Pseudomonas
Authors: Ramos J. L. , Mermod N. , Timmis K. N.
Published: October 2006

TOL plasmid PWWO of Pseudomonas putida contains two operons that specify a pathway for the degradation of aromatic hydrocarbons. The ‘upper’ operon encodes enzymes for the oxidation of toluene to benzoate and xylenes to toluates, whereas the meta‐cleavage operon specifies the further oxidation of benzoate and toluates. Transcription of the upper pathway operon (s positively regulated by the XylR protein, which is activated by toluene/xylenes and their alcohol catabolic products, in combination with the NtrA protein, a sigma factor. Expression of the meta‐operon is positively controlled by the XylS protein which is activated by meta‐pathway substrates, and is Independent of NtrA protein. Expression of the meta pathway is also Induced by toluene/xylene‐activated XylR protein via a cascade regulatory system in which this protein in combination with NtrA protein stimulates transcription from the xylS gene promoter. Hyper‐production of XylS protein in turn provokes high level expression of the meta‐operon, which is independent of meta‐pathway substrates. The two promoters, which are activated by the XylR and NtrA proteins, the upper pathway promoter and the xylS gene promoter, exhibit three regions of homology centred at –12(5′–TTGCTÃG–3′), –24(5′ ‐TGGCPuT –3) and –45(5′‐TTAAATÃGPuPuGCGPuTc‐3′), with respect to their principal transcription initiation points. The possible physiological significance of activated XylR‐protein‐induced expression of the meta‐operon through amplification of XylS protein levels is considered.
Nucleotide sequencing of the structural gene for colicin N reveals homology between the catalytic, C‐terminal domains of colicins A and N
Authors: Pugsley A. P.
Published: October 2006

An 1800 bp fragment of DNA from a natural ColN plasmid (pCHAP4) encompassing the colicin N structural gene (cna) and its regulatory region was subjected to nucleotide sequencing and deletion analysis. The region of DNA immediately upstream from cna contains two tandemly‐arranged and overlapping potential LexA binding sites (SOS boxes), in line with the previous demonstration that cna expression is repressed by LexA protein. Deletion of the LexA binding site allowed efficient transcription of cna from an upstream lacZ promoter, whereas its presence reduced lacZ‐promoted cna expression to varying extents depending on the proximity of lacZp and the SOS boxes. The molecular weight of colicin N, as deduced from the nucleotide sequence, is 41696, which is ciose to the experimentally determined molecular weight of 39000. Colicin N has a glycine‐rich amino terminus similar to that found in many other colicins. Part of the glycine‐rich domain of colicin N could be replaced by an unrelated sequence devoid of glycine residues without affecting either colicin release or activity. The carboxy‐terminal half of colicin N exhibits significant homology to the C‐terminus of colicin A. The latter colicin forms pores In the cyto‐plasmic membrane of Escherichia coli, thereby depolarizing the membrane and causing cell death. The C‐terminus of colicin A is endowed with this catalytic activity. Although colicin N was previously found to cause lysis of Escherichia coli cells, a more detailed Investigation revealed that it too depolarizes the Escherichia coli cytopiasmic membrane and that lysis is a secondary effect.
Defective Escherichia coli signal peptides function in yeast
Authors: Pines O. , Lunn C. A. , Inouye M.
Published: October 2006

To investigate structural characteristics important for eukaryotic signal peptide function In vivo, a hybrid gene with interchangeable signal peptides was cloned into yeast. The hybrid gene encoded nine residues from the amino terminus of the major Escherichia coli lipoprotein, attached to the amino terminus of the entire mature B. coli β‐lactamase sequence. To this sequence were attached sequences encoding the non‐mutant E. coli lipoprotein signal peptide, or lipoprotein signal peptide mutants lacking an amino‐terminal cationic charge, with shortened hydrophobic core, with altered potential helicity, or with an altered signal‐peptide cleavage site. These signal‐peptide mutants exhibited altered processing and secretion in E. coli. Using the GAL10 promoter, production of all hybrid proteins was induced to constitute 4–5% of the total yeast protein. Hybrid proteins with mutant signal peptides that show altered processing and secretion in E. coli, were processed and translocated to a similar degree as the non‐mutant hybrid protein in yeast (approximately 36% of the total hybrid protein). Both non‐mutant and mutant signal peptides appeared to be removed at the same unique site between cysteine 21 and serine 22. one residue from the E. coli signal peptidase II processing site. The mature lipo‐β‐lactamase was translocated across the cytoplasmic membrane into the yeast periplasm. Thus the protein secretion apparatus in yeast recognizes the lipoprotein signal sequence in vivo but displays a specificity towards altered signal sequences which differs from that of E. coli.
A replication region of the IncHI plasmid, R27, is highly homologous with the RepFIA replicon of F
Authors: Saul D. , Lane D. , Bergquist P. L.
Published: October 2006

A region of the IncHl plasmid R27 has been found to share very close nucleotide sequence homology with the RepFIA replicon of F. This region has been located on a 1.6 kb segment of R27 plasmid DNA, and corresponds to ori‐2 and the E gene of F. The IncC repeat sequence region shows reduced homology, with the F repeats being an imperfect subset of a larger repeated sequence found in R27. The E gene homologue of R27 is able to initiate replication from the F ori‐2 sequence and to repress the E gene promoter of F. The results are consistent with the observed incompatibility behaviour of R27, and have a bearing on the specificity of interaction of E protein with its DNA‐binding sites.
Cloned structural genes for the osmotically regulated binding‐protein‐dependent glycine betaine transport system (ProU) of Escherichia coli K‐12
Authors: Faatz E. , Middendorf A. , Bremer E.
Published: October 2006

The proU locus of Escherichia coli encodes a high‐affinity, binding‐protein‐dependent transport system (ProU) for the osmoprotectant glycine betaine. We cloned this locus into both low‐copy‐number lambda vectors and multicopy plasmids and demonstrated that these clones restore osmotically controlled synthesis of the periplasmic glycine betaine binding protein (GBBP) and the transport of glycine betaine in a δ(proU) strain. These clones allowed us to investigate the influence of osmolarity on ProU transport activity independent of the osmotically controlled expression of proU. ProU activity was strongly stimulated by a moderate increase in osmolarity and was partially inhibited by high osmolarity. This activity profile differs from the profile of the osmotically regulated proU expression. The proU locus is organized in an operon and the position of the structural gene (proV) for GBBP is defined using a minicell system. We determined that at least three proteins (in addition to GBBP) are encoded by the proU locus. We also investigated the permeation of glycine betaine across the outer membrane. At low substrate concentration (0.7 μM), permeation of glycine betaine was entirely dependent on the OmpF and OmpC porins.
Amino acid sequence homology between the enzymic domains of diphtheria toxin and Pseudomonas aeruginosa exotoxin A
Authors: Carroll S. F. , Collier R. J.
Published: October 2006

Despite similarities In their enzymic properties, diphtheria toxin (DT) and exotoxin A (ETA) of Pseudomonas aeruginosa have major differences in structure and action: consequently, the question of possible evolutionary relatedness of these two proteins remains unanswered. Here we report the existence of significant amino acid sequence homology between the enzymic domain of DT and that of ETA. Iajor segments of sequence may be aligned with high percentages of identity and of conservative substitutions. The homologous stretches in ETA form much of the active‐site cleft in the X‐ray crystallographic structure. This evidence implies that these domains, at least, have diverged from a common ancestral protein and that active‐site residues have been strongly conserved.
Regulation of components of the Pseudomonas aeruginosa phosphate‐starvation‐inducible regulon in Escherichia coli
Authors: Siehnel R. J. , Worobec E. A. , Hancock R. E. W.
Published: October 2006

Plasmids pPBP and pRS‐XP containing the cloned genes for the Pseudomonas aeruginosa phosphate‐starvation‐ inducible periplasmic phosphate‐binding protein and outer membrane porin P (oprP), respectively, were introduced into various Escherichia coli Pho‐regulon regulatory mutants. Using Western immunoblots and specific antisera, the production of both gene products was observed to be under the control of regulatory elements of the E. coli Pho regulon. Sequencing of the region upstream of the translational start site of the oprP gene revealed a ‘Pho box’ with strong homology to the E. coli consensus ‘Pho box’, the putative binding site of the PhoB activator. Since P. aeruginosa and E. coli belong to different families and have quite different GC contents, these data suggest strong evolutionary conservation of regulatory elements of the Pho regulon.
Covalent modification of ribulose 1,5‐bisphosphate carboxylase/oxygenase in Rhodomicrobium vannielii
Authors: Mann N. H. , Turner A. M.
Published: October 2006

The most abundant phosphorus‐containing polypeptide in the purple non‐sulphur bacterium Rhodomicrobium vannielli has been identified by a combination of immunoprecipitation and sucrose density gradient centrifugation as the large subunit of ribulose 1,5 bisphosphate carboxylase/oxygenase. The covalent modification of the large subunit involves the phosphorylation of one or more tyrosine residues and appears to occur prior to assembly of the large subunit into the mature enzyme. In addition, the phosphorylated form of the large subunit was found to exist in at least two distinct protein complexes of M, 410000 and 440000.
Inactivation of the FNR protein of Escherichia coli by targeted mutagenesis in the N‐terminal region
Authors: Spiro S. , Guest J. R.
Published: October 2006

The FNR protein of Escherichia coli is a regulatory protein that activates the transcription of its target genes in response to oxygen limitation. Site‐directed mutagenesis was used to show that a 28‐residue N‐terminal segment containing three cysteines is essential for normal FNR function. The cysteine residue which is centrally located in the three‐cysteine cluster (Cys‐Ala‐Ile‐His‐Cys‐Gln‐Asp‐Cys) was also shown to be essential for FNR activity. Possible mechanisms by which this cysteine residue might function in the response of FNR to anaerobiosis are discussed.
Suppression of IIIGlc‐defects by Enzymes IINag and IIBgl of the PEP:carbohydrate phosphotransferase system
Authors: Vogler A. P. , Broekhuizen C. P. , Schuitema A. , Lengeler J. W. , Postma P. W.
Published: October 2006

The Enzymes II of the PEP:carbohydrate phosphotransferase system (PTS) specific for N‐acetylglucosamine (IINag) and β‐glucosides (IIBgl) contain C‐terminal domains that show homology with Enzyme IIIGlc of the PTS. We investigated whether one or both of the Enzymes II could substitute functionally for IIIGlc. The following results were obtained: (i) Enzyme IINag, synthesized from either a chromosomal or a plasmidencoded nagE+ gene could replace IIIGlc in glucose, methyl α‐glucoside and sucrose transport via the corresponding Enzymes II. An Enzyme IINag with a large deletion in the N‐terminal domain but with an intact C‐terminal domain could also replace IIIGlc in IIGlc‐dependent glucose transport, (ii) After decryptification of the Escherichia coli bgl operon, Enzyme IIBgl could substitute for IIIGlc. (iii) Phospho‐HPr‐dependent phosphorylation of methyl α‐glucoside via IINag/IIGlc is inhibited by antiserum against IIIGlc as is N‐acetyl‐glucosamine phosphorylation via IINag. (iv) In strains that contained the plasmid which coded for IINag, a protein band with a molecular weight of 62000 D could be detected with antiserum against IIIGlc. We conclude from these results that the IIIGlc‐like domain of Enzyme IINag and IIBgl can replace IIIGlc in IIIGlc‐dependent carbohydrate transport and phosphorylation.
Germination‐specific cortex‐lytic enzyme is activated during triggering of Bacillus megaterium KM spore germination
Authors: Foster S. J. , Johnstone K.
Published: October 2006

Antibodies were raised against purified germinationspecific cortex‐lytic enzyme (GSLE) from spores of Bacillus megaterium KM which neutralized the ability of GSLE to germinate permeabilized spores. Western blotting of dormant spore and vegetative cell fractions separated by SDS‐PAGE demonstrated that GSLE is spore‐specific and that >90% of the GSLE is associated with the dormant spore cortex peptidoglycan as a phosphorylated 63 kD pro‐form, which could only be visualized after lysozyme digestion of the peptidoglycan. During germination, the 63 kD pro‐form of GSLE is processed to release the active enzyme, which had an apparent molecular weight of 30 kD. Inhibitor studies demonstrated that GSLE activation occurs as part of the commitment reaction and thus represents the first‐identified enzymatic event to occur during germination triggering. Proteins that cross‐react with anti‐GSLE sera are present in spore fractions of other species.
Phylogeny of metabolic pathways: O‐acetylserine sulphydrylase A is homologous to the tryptophan synthase beta subunit
Authors: Levy S. , Danchinl A.
Published: October 2006

The cysK gene of Escherichia coli K‐12 encoding O‐acetylserine sulphydrylase A, was cloned and its nucleotide sequence, together with that of the flanking regions, was determined. The deduced amino acid sequence of the carboxy‐terminal moiety of O‐acetylserine sulphydrylase A shows significant similarity to the amino acid sequence of tryptophan synthase beta chain from several organisms. This sequence similarity is likely to reflect the structural homologies of substrates shared by both enzymes. This may indicate that these proteins, although catalysing different reactions in different metabolic pathways, have evolved from a common ancestral gene.
Secretion and processing of the Bacillus subtilis endo‐β‐1,3‐1,4‐glucanase in Escherichia coli
Authors: Gormley E. P. , Cantwell B. A. , Barker P. J. , Gilmour R. S. , McConnell D. J.
Published: October 2006

The endo‐β‐1,3‐1,4‐glucanase enzyme of Bacillus subtilis C120, when synthesized in Escherichia coli, is located mainly in the cytoplasm, but enzyme activity is also detected in the periplasmic space and in the extracellular medium. The proportion recovered in the extracellular medium is not altered by changes in the levels of synthesis of the enzyme. Lysis of E. coli cells is ruled out as the cause of the secretion by the normal localization of β‐galactosidase, an intracellular protein. However, β‐lactamase, which is normally found in the periplasmic space, is detected in the extracellular medium of E. coli transformants containing β‐glucanase plasmids, suggesting that the presence of β‐glucanase in the cell alters the permeability of the outer membrane. The β‐glucanase proteins found in the extracellular medium, the periplasmic space and the cytoplasm have the same electrophoretic mobilities as the secreted enzyme of B. subtilis. Amino‐terminal sequencing has shown that the β‐glucanase enzyme in the intracellular fraction of E. coli is processed at a site two amino acids distant from the processing site used in B. subtilis.
Characterization of a protein inhibitor of extracellular proteases produced by Erwinia chrysanthemi
Authors: Létoffé S. , Delepelaire P. , Wandersman C.
Published: October 2006

Erwinia chrysanthemi, a phytopathogenic bacterium, produces a protease inhibitor which is a low‐molecu‐lar‐weight, heat‐stable protein. In addition to its action on the three E. chrysanthemi extracellular proteases A, B and C, it also strongly inhibits the 50 kD extracellu‐lar protease of Serratia marcescens. Its structural gene (inh) was subcloned and expressed in Escher‐ichia coli, in which it encodes an active inhibitor which was purified. The nucleotide sequence of the inh gene shows an open reading frame of 114 codons. The N‐terminal amino acid sequence of the purified inhibi‐tor was also determined. It indicated the existence of an amino‐terminal signal peptide absent from the mature protein. The inhibitor is entirely periplasmic in E. chrysanthemi and partially periplasmic in E. coli.
Transcription of rhiA, a gene on a Rhizobium leguminosarum bv. viciae Sym plasmid, requires rhiR and is repressed by flavanoids that induce nod genes
Authors: Economou A. , Hawkins F. K. , Downie J. A. , Johnston A. W. B.
Published: October 2006

Strains of Rhizobium leguminosarum biovar viciae specifically make an abundant protein (Rhi) in free‐living culture but not in bacteroids. Genes needed for Rhi synthesis are on a Sym plasmid and here we show that one of these genes, rhiA, is the structural gene that specifies this polypeptide. Transcription of rhiA requires a regulatory gene, rhiR, located close to rhiA and to nod genes involved in nodulation. Mutations in rhiA or rhiR do not appear to affect symbiotic nitrogen fixation. Transcription of rhiA is repressed in cells grown in the presence of the flavanone hesperetin or the flavone apigenin, both of which are potent inducers of transcription of nod genes. This was deduced from the use of rhiA‐lacZ fusions; however, when the Rhi polypeptide was detected in SDS gels, there was no apparent difference in the intensity of its staining in extracts obtained from cells grown with or without these flavanoid nod gene inducer molecules. However, a mutation in a nodulation gene, nolR, also closely linked to the nod and rhi genes, caused a severe depression in the amount of Rhi (as seen on gels) that was made in cells grown in the presence of inducer flavanoids.
Cloning and characterization of NSP1, a locus encoding a component of a CDC25‐dependent, nutrient‐responsive pathway in Saccharomyces cerevisiae
Authors: Tripp M. L. , Bouchard R. A. , Pinon R.
Published: October 2006

The NSP1 gene in Saccharomyces cerevisiae has been identified by its ability, when expressed at high levels, to bypass the CDC25 requirement for growth. Sequence analysis of the cloned NSP1 locus suggests that the NSP1 product contains 269 amino acids and has a membrane‐spanning domain at its carboxyl terminus. The NSP1 protein does not have sequence similarity to other known proteins, and is not related to the CDC25 protein, or to any of the previously described suppressors of CDC25 mutants. Phosphoprotein analysis of NSP1‐suppressed cells indicates that the NSP1 product controls the phosphorylation of two 31 kD proteins whose phosphorylation and de‐phosphorylation are strongly correlated with cell‐cycle arrest and proliferation, respectively, and suggests that the NSP1 product is an important downstream element of a CDC25‐dependent, nutrient‐responsive, phosphorylation pathway.
Transcriptional regulation of ceil division genes in Escherichia coli
Authors: Dewar S. J. , Kagan‐Zur V. , Begg K. J. , Donachie W. D.
Published: October 2006

The complete Escherichia coli ftsQ coding sequence, together with part of the ftsA coding sequence, has been cloned upstream of the lacZ open reading frame in a λ‐vector (λJFL100). Cells which are lysogenic for λJFL100 transcribe the cloned lacZ from promoter(s) within the ftsQ and ftsA sequences. The level of β‐galactosidase produced is dependent on growth rate (and/or cell size) and Is derepressed in an ftsA‐deficient mutant. Transcription during the cell cycle is restricted to the time of cell division.
Location and molecular cloning of the structural gene for the deoxyguanosine triphosphate triphosphohydrolase of Escherichia coli
Authors: Quirk S. , Seto D. , Bhatnagar S. K. , Gauss P. , Gold L. , Bessman M. J.
Published: October 2006

The structural gene for deoxyguanosine triphosphate triphosphohydrolase (dGTPase) (EC 3.1.5.1) and its regulator, optA, have been located on a lambda phage carrying a 17.5kb Escherichia coli DNA insert. The DNA fragment has been excised and ligated into pBR325 and also transferred to another lambda vector. From the results of transduction and transformation experiments, we find that the structural gene for dGTPase is very closely linked to optA and dapD, which locates it at approximately 3.6 minutes on the genetic map of E. coli K12. We propose the mnemonic dgt as the designation for the structural gene for this enzyme.
Nucleotide sequence of the regulatory nifA gene of Rhizobium leguminosarum PRE: transcriptional control sites and expression in Escherichia coli
Authors: Roelvink P. W. , Hontelez J. G. J. , van Kammen A. , van den Bos R. C.
Published: October 2006

We report the sequence of the regulatory nifA gene of Rhizobium leguminosarum PRE. The transcription initiation and termination sites of nifA were mapped and a potential promoter and a rho‐independent terminator identified. The nifA gene has two possible translation start sites, both of which are used in an Escherichia coli background, resulting in proteins with apparent molecular weights of 58kD and 57kD; initiation at the second site is preferred over initiation at the first. The nifA‐nifB intergenic region contains an rpoN‐dependent promoter for the nifB gene but no consensus upstream activator sequence (UAS).

A potential DNA‐binding domain, consisting of two α‐helices separated by a four‐amino‐acid linker, is located at the C‐terminal end of the NifA amino acid sequence.
Mammalian cell adhesion functions and cellular penetration of enteropathogenic Yersinia species
Authors: Isberg R. R.
Published: October 2006

The entry of enteropathogenic Yersinia into cultured mammalian ceils has been studied in order to gain insight into the mechanism of bacterial penetration into host cells during infection. There exist at least three pathways for entry by Yersinia into mammalian cells, the most efficient of which is promoted by invasin, the product of the inv gene. Invasin is an outer membrane protein that attaches to a mammalian cell receptor, initiating the entry process. Several receptors that bind invasin have been identified, and each is a member of the VLA family of integrin cell adhesion molecules. The role of integrins in the entry process is discussed, as is the ability of invasin to stimulate uptake by binding to its integrin receptor.
Phosphoribosylpyrophosphate (PRPP)‐less mutants of Escherichia coli
Authors: Hove‐Jensen B.
Published: October 2006

A DNA fragment encoding kanamycin resistance was inserted in vitro into a plasmid‐borne prs gene encoding phosphoribosylpyrophosphate synthetase of Escherichia coli. The resulting plasmids were subsequently transferred to the chromosome by homologous recombination and the haploid strains prs‐3::KanR and prs‐4::KanR were obtained. These strains were fully viable, but required guanosine, uridine, histidine, tryptophan and nicotinamide mononucleotide. There was no phosphoribosylpyrophosphate synthetase activity or phosphoribosylpyrophosphate pool in the mutant strains. These results show that phosphoribosytpyrophosphate synthetase is dispensable for E. coli.
Mapping the surface regions of Pseudomonas aeruginosa PAK pilin: the importance of the C‐terminal region for adherence to human buccal epithelial cells
Authors: Lee K. K. , Doig P. , Irvin R. T. , Paranchych W. , Hodges R. S.
Published: October 2006

The adherence of non‐mucoid Pseudomonas aeruginosa strains is believed to be mediated by the pilus, which consists of a single protein subunit of 15000 Oaltons called pilin. Ten antipeptide antisera were raised to map the surface regions of pilin from P. aeruginosa strain K (PAK). Only one of the antipeptide antisera to the eight predicted surface regions failed to react with PAK pili in direct ELISA. Five out of eight synthetic peptides representing the eight predicted surface regions reacted with anti‐PAK pilus anti‐serum, indicating their surface exposure. Combining the antipeptide and antipilus antisera results, all eight predicted surface regions were demonstrated to be surface‐exposed. The PAK 128‐144‐OH peptide produced the best binding antiserum to PAK pili. Only antipeptide Fab fragments directed against the disulphide bridged C‐terminal region of PAK piiin blocked the adherence of pili to human buccal epithelial cells, which suggests that this region contains the receptor‐binding domain of the PAK pilus.
Cloning of a β‐tubulin gene from Plasmodium falciparum
Authors: Delves C. J. , Ridley R. G. , Goman M. , Holloway S. P. , Hyde J. E. , Scaife J. G.
Published: October 2006

We describe the isolation and characterization of a gene for β‐tubulin from the malaria parasite, Plasmodium falciparum. This organism appears to contain a single gene encoding β‐tubulin. A single transcript from this gene can be detected in the total RNA of the parasite's asexual blood stages. The complete sequence for the gene has been elucidated. It has two introns, one of which has a position identical to that of a related parasite, Toxoplasma gondii. The gene shows the usual preference for codons with A or T in the third position. The predicted amino acid sequence is compared with that of T. gondii and the human host. Further comparisons between these and fungal sequences of β‐tubulins resistant to benomyl, a drug binding this protein, highlight differences that could be exploited in the development of parasite‐specific anti‐tubulin drugs.
Characterization of the osmoregulated Escherichia coli proU promoter and identification of ProV as a membrane‐associated protein
Authors: May G. , Faatz E. , Lucht J. M. , Haardt M. , Bolliger M. , Bremer E.
Published: October 2006

The Escherichia coli proU operon encodes a high‐affinity, binding‐protein‐dependent transport system for the osmoprotectant glycine betaine. Expression of proU is osmoregulated, and transcription of this operon is greatly increased In cells grown at high osmolarity. Characterization of the proU operon and its promoter provided results similar to those published elsewhere (Gowrishankar, 1989; Stirling et al., 1989). The previously identified proU601 mutation, which leads to increased proU expression both at low‐and high osmolarity, is a G to A transition in the Pribnow box of the proU promoter, which increases the homology of the ‐10 region to the consensus sequence of E. coli promoters. Using an antiserum raised against a ProV‐β‐galactosidase hybrid protein, we have identified ProV as a protein associated with the cytoplasmic membrane. This cellular location is consistent with its proposed role as the energy ‐coupling component of the ProU transport system.