bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pullulanase secretion in Escherichia coli K‐12 requires a cytoplasmic protein and a putative polytopic cytoplasmic membrane protein
Authors: Possot O. , D'Enfert C. , Reyss I. , Pugsley A. P. 
Published: October 2006

SummaryThe previously uncharacterized third and fourth genes (pulE and pulF) of the pullulanase secretion gene operon of Klebsiella oxytoca strain UNF5023 are, respectively, predicted to encode a 55 kDa polypeptide with a putative nucleotide‐binding site, and a highly hydrophobic 44 kDa polypeptide that probably spans the cytoplasmic membrane several times. Expression of pulE in minicells or under the control of a strong bacteriophage T7 promoter resulted in the production of a c. 58 kDa cytopLasmic protein. A representative PulE‐β‐galactosidase hybrid protein created by Tnlac mutagenesis was also found mainly in the cytoplasm. These results are in line with the predicted absence from PulE of a region of sufficient hydrophobicity to function as a signal sequence. The PulF polypeptide could not be detected either in minicells or when the gene was transcribed from the T7 promoter, but the acquirement of three pulF‐lacZ gene fusions that encoded hybrid proteins with relatively high levels of β‐galactosidase activity indicates that this gene can be transcribed and translated. Gene disruption experiments indicated that both pulE and pulF are required for pullulanase secretion in Escherichia coli K‐12. Both proteins exhibit considerable homology throughout their entire lengths with other proteins involved in protein secretion, pilin assembly, conjugation and transformation competence in a variety of bacteria. In addition, PulE protein has consensus sequences found in a wide variety of nucleotide‐binding proteins. This study completes the initial characterization of the pullulanase secretion gene operon, which comprises 13 genes that are all essential for the transport of pullulanase across the outer membrane.
Cytotoxic activity of a recombinant chimaeric protein between Pseudomonas aeruginosa exotoxin A and Corynebacterium diphtheriae diphtheria toxin
Authors: Guidi‐Rontani Chantal 
Published: October 2006

SummaryA segment of the exotoxin A gene of Pseudomonas aeruginosa, coding for the N‐terminal end of domain I and domain II of the toxin (ETA), was genetically fused to the diphtheria toxin gene of Corynebacterium diphtheriae, coding for the N‐terminal end of A fragment of diphtheria toxin (DT). The resulting hybrid protein (termed CED1) was produced in large amounts and exported to the periplasm in Escherichia coli. This chimaeric protein reacted with both anti‐ETA and anti‐DT antisera. Furthermore, the chimaeric protein displayed ADP‐ribosylation activity and exhibited cytotoxicity to mouse 3T6 fibroblasts. These results demonstrated that the chimaeric protein is cytotoxic, and that the toxic potential of DTA can be selectively internalized and translocated via domains I and II of exotoxin A, which are thus sufficient to direct and translocate an enzymatically active heterologous polypeptide segment into the cytosol of sensitive cells.
Transcriptional control of sex‐pheromone‐inducible genes on plasmid pAD1 of Enterococcus faecalis and sequence analysis of a third structural gene for (pPD1 ‐encoded) aggregation substance
Authors: Galli D. , Friesenegger A. , Wirth R. 
Published: October 2006

SummaryThe expression of several neighbouring genes on plasmid pAD1 that are necessary for conjugation depend on induction with sex pheromone CAD1. Analyses of transcripts by Northern blot hybridization demonstrated that the genes seal (encoding surface exclusion protein) and asa 1 (encoding aggregation substance) are transcribed independently. Both genes are organized in different operons together with neighbouring open reading frames of unknown function. Several transcripts could be identified for seal and asa1. Their transcriptional start sites were determined by primer extension experiments, confirming the results of the Northern blot experiments. We also could identify seal‐ and iad‐ (encoding an inhibitory peptide counteracting sex pheromone CAD1) specific transcripts which are expressed constitutively, but to a lower extent relative to induced conditions. In addition, we localized the asp1 gene coding for aggregation substance of sex pheromone plasmid pPD1 and determined its DNA sequence, which was found to be highly homologous to asa1 (aggregation substance gene of pAD1) and prgB (aggregation substance gene of pCFiO). The structural genes were found to be organized more or less identically on the three sex‐pheromone plasmids pAD1, pCF10, and pPD1, and to be highly conserved. Regions supposed to be of crucial importance for regulatory functions, however, were found to differ. We also could identify some conserved DNA motifs which might be potential target sites for transcriptional regulators. In combination these data allowed us to formulate a model for the regulation of sex‐pheromone‐induclble genes of plasmid pAD1. Its main statement is that only in the presence of cAD1 can the gene traE1 be transcribed. The positive regulatory factor TraE1 then can trigger expression of the structural genes seal and asa1.
The amino acid sequence of a Bacillus subtilis phosphoprotein that matches an orfY‐tsr coding sequence
Authors: Mitchell Clayton , Morris Paul W. , Lum Leanna , Spiegelman George , Vary James C. 
Published: October 2006

Summary Bacillus subtilts contains a 30 kDa protein which was phosphorylated during late vegetative growth and sporulation. The sequence for the N‐terminal 16 amino acids was found to be identical to the predicted sequence for the N‐terminus of a small open reading frame, orfY, but diverged from the predicted sequence thereafter. The orfY region was resequenced and contained one less adenine residue than previously reported, resulting in an open reading frame from within orfy through the entire coding region for tsr which follows orfY. The predicted orfY‐tsr amino acid sequence showed 24% identity to Escherichia coll fructose–1,6‐bisphosphate aldolase. Two mutants in the tsr region had 2–5% of wild‐type aldolase and the nucleotide sequences showed missense mutations. These results indicate that orfY‐tsr encodes aldolase and should be renamed fba 1.
nov: a new genetic locus that affects the response of Escherichia coli K‐12 to novobiocin
Authors: Rakonjac Jasna , Milic Mirjana , Ajdic‐Predic Dragana , Santos Diogenes , Ivanisevic Radmila , Savic Dragutin J. 
Published: October 2006

SummaryWe have identified a new gene locus (nov) affecting the resistance of Escherichia coli K‐12 to novobiocin. The gene also affects, although to a lesser extent, tolerance to another gyrase inhibitor coumermycin. Transductional and complementation analysis show that nov is located between attø80 and the osmZ (hns) genes at minute 27 of the E. coli K‐12 genetic map. In standard laboratory strains of E. coli K‐12 nov exists at least in two allelic forms.
Activator‐independent formation of a closed complex between σ54‐holoenzyme and nifH and nifU promoters of Klebsiella pneumoniae
Authors: Buck Martin , Cannon Wendy 
Published: October 2006

SummaryThe alterNatlve sigma factor σ54 is required for transcription of nitrogen fixation genes in Klebsiella pneutnoniae and other diazotrophs. The nif genes, and other Eσ54‐dependent genes whose products are necessary for a wide range of processes, are positively regulated. A unifying model that is well supported by studies on nif and other nitrogen‐regulated (ntr) genes includes the central tenet that σ54 confers upon core RNA polymerase the ability to recognize and bind specific promoter sequences, but not the ability to isomerize to the open complex without assistance from the appropriate activator protein. Direct physical evidence for formation of an activator‐independent complex between Eσ54 and the NifA‐dependent K. pneumoniae nifH and nifU promoters has, to date, been lacking. Using purified components we have now demonstrated formation of the closed complex at these promoters, indicating that it is an intermediate along the pathway to open complex formation. The closed complex was not detected when conserved features of the promoter were altered by mutation, nor was its stability increased when integration host factor protein was bound adjacent to the Eσ54 recognition sequence.
In vivo control of promoter and terminator efficiencies at a distance
Authors: Jacquet M. A. , Reiss C. 
Published: October 2006

SummaryIn pBR329, the genes providing resistance to ampicillin (β‐lactamase, bla) and chloramphenicol (chloramphenicol acetyl transferase, cat) are encoded on the same strand. The bla gene lies downstream of the cat gene, separated by an intergenic sequence of 414 bp. The transcription starts of the two genes are 1090 bp apart. We have probed, in vivo, the effect on transcription of the bla gene, of the introduction, in front of the cat gene, of a series of synthetic promoters covering a large (over 60‐fold) range of efficiency. The rising efficiency of the cat promoter has several important consequences for transcription of the bla gene. First, a strong (up to sevenfold) stimulation of the bla promoter is observed, together with a shift of the main bla transcription start site, 10 bp upstream. Furthermore, the relative efficiencies of the bla transcription terminators are reduced. Finally, because of a lesser relative efficiency of the car transcription terminators as well, we observe enhanced intrusion into the bla gene of transcripts initiated at the cat promoter, some of them extending to the bla transcription terminator and beyond. The operon‐like expression of the cat‐bla gene tandem is controlled by the efficiency of the cat terminator, which in turn depends on that of the cat promoter. This demonstrates a direct link between the efficiencies of promoter and terminator. Upon inhibition of bacterial gyrase activity, i.e. relaxation of negative supercoiling action, bla expression increases sharply in pBR329, but remains almost unchanged in a plasmid (pBRGC‐1) in which cat is under the control of a 6.5‐fold stronger promoter. Therefore, under normal gyrase activity, the stimulation of the bla promoter in pBRGC‐1 (relative to pBR329) appears to be linked to topological relaxation of its template in situ, in keeping with earlier in vitro observations. We propose that the relaxed state of pBRGC‐1 in situ could be due to the decrease in the plasmid linking number, introduced by the 10–12 RNA polymerases that simultaneously transcribe the cat gene in that plasmid, compared with only one or two in pBR329. We find that the negative superhelical densities of both plasmids are almost identical when extracted from the cell. Therefore gyrase would not correct for the relaxed state of plasmid pBRGC‐1 observed in situ.
Human neutrophil response to recombinant neisserial Opa proteins
Authors: Belland R. J. , Chen T. , Swanson J. , Fischer S. H. 
Published: October 2006

SummaryInteractions of human neutrophils with recombinant Escherichia coli expressing gonococcal outer membrane Opa proteins were examined using chemiluminescent and biological assays. Seven opa loci from Neisseria gonorrhoeae MS11 4.8 were expressed as β‐lactamase‐Opa fusion proteins that contained all but the mature N‐terminal amino acid of the full‐length Opa protein fused to three N‐terminal amino acids derived from the mature β‐lactamase. The Opa fusion proteins were exported and assembled in the outer membrane of E. coli in a manner similar to that of Opa in N. gonorrhoeae, as evaluated by antibody binding and in situ proteolytic cleavage. All fusion proteins exhibited the characteristic heat‐modifiable migration in SDS‐polyacrylamide gel electrophoresis that typifies Opa proteins of neisseriae. Opa fusion proteins conferred on E. coli the ability to stimulate a chemiluminescent response from human neutrophils in the absence of antibody or complement. The nature of the response in terms of chemiluminescence, phagocytosis, and killing was in all cases analogous to that seen using N. gonorrhoeae expressing the equivalent Opa protein. Neither E. coli nor gonococci expressing OpaA elicited a response from neutrophils. Use of E. coli expressing Opa fusions should be useful in defining their biological activities and pathogenic roles.
Transcription and autoregulation of the stabilizing functions of broad‐host‐range plasmid RK2 in Escherichia coli, Agrobacterium tumefaciens and Pseudomonas aeruginosa
Authors: Davis Tamara L. , Helinski Donald R. , Roberts Richard C. 
Published: October 2006

SummaryThe broad‐host‐range plasmid RK2 has been shown to encode several proteins important for its maintenance within bacterial populations of a number of Gram‐negative bacteria. Their genes are organized into two operons: parCBA and parD. These operons have been proposed to be transcribed from two divergent promoters, p‐parCBA and p‐parD, located within a sequence of approximately 150 bases. In this report we identify and characterize the sequences required for regulated transcription from these promoters in Escherichia coli, Agrobacterium tumefaciens and Pseudomonas aeruginosa. Both of these promoters are repressed by their own gene products in the same manner in all three bacteria tested, with ParA functioning as the primary repressor of p‐parCBA and ParD functioning as the repressor of p‐parD. The binding regions of these proteins were determined through deletion analyses, DNA mobility shift assays, and an examination of the effect of mutations in this region. Based on these observations, the ParA protein appears to bind to either two inverted repeat or two direct repeat sequences, one downstream from the transcriptional initiation site and the other upstream of the p‐parCBA ‐35 box. The ParD protein appears to bind to one inverted repeat sequence, located between the ‐35 and ‐10 boxes of p‐parD.
Characterization of a novel regulatory gene governing the expression of a polyketide synthase gene in Streptomyces ambofaciens
Authors: Geistlich Martin , Losick Richard , Turner Jan R. , Rao R. Nagaraja 
Published: October 2006

SummaryA key step in the biosynthesis of macrolide antibiotics is the assembly of a large macrocyclic lactone ring by a multienzyme protein complex called the polyketide synthase. In the species Streptomyces ambofaciens, the polyketide synthase for the assembly of the 16‐membered ring of the macrolide antibiotic spiramycin is encoded by the biosynthetic gene srmG. Here we show that the accumulation of transcripts from the srmG promoter is governed by the regulatory gene srmR, whose predicted product, a 65 kDa polypeptide, is not significantly similar in its deduced amino acid sequence to that of previously reported proteins in the protein databases. The srmR gene product is also required for the accumulation of transcripts from srmX, an additional gene in the vicinity of srmR, but not for the accumulation of transcripts from srmR itself. Interestingly, mutations in srmR prevent the accumulation of transcripts from the spiramycin resistance gene srmB, but this is an indirect consequence of the failure of srmR mutants to produce spiramycin, which is an inducer of its own resistance gene. The possibility that srmR is the prototype for a new class of regulatory genes governing early events in the biosynthesis of macrolide antibiotics is discussed.
Sequence diversity within the argF, fbp and recA genes of natural isolates of Neisseria meningitidis: interspecies recombination within the argF gene
Authors: Zhou Jiaji , Spratt Brian G. 
Published: October 2006

SummaryStudies of natural populations of Neisserla meningitidis using multilocus enzyme electrophoresis have shown extensive genetic variation within this species, which, it has been proposed, implies a level of sequence diversity within meningococci that is greater than that normally considered as the criterion for species limits in bacteria. To obtain a direct measure of the sequence diversity among meningococci, we obtained the nucleotide sequences of most of the argF, recA and fbp genes of eight meningococci of widely differing electrophoretic type (from the reference collection of Caugant). Sequence variation between the meningococcal strains ranged from 0–0.6% for fbp, 0–1.3% for argF, and 0–3.3% for recA. These levels of diversity are no greater than those found within Escherichia coli‘housekeeping’genes and suggest that multilocus enzyme electrophoresis may overestimate the extent of nucleotide sequence diversity within meningococci. The average sequence divergence between the Neisseria meningitidis strains and N. gonorrhoeae strain FA19 was 1.0% for fbp and 1.6% for recA. The argF gene, although very uniform among the eight meningococcal isolates, had a striking mosaic structure when compared with the gonococcai argF gene: two regions of the gene differed by >13% in nucleotide sequence between meningococci and gonococci, whereas the rest of the gene differed by <1.7%. One of the diverged regions was shown to have been introduced from the argF gene of a commensal Neisseria species that is closely related to Neisseria cinerea. The source of the other region was unclear.
Activation of a cryptic streptomycin‐resistance gene in the Bacteroides erm transposon, Tn4551
Authors: Smith C. Jeffrey , Owen Charles , Kirby Lyndon 
Published: October 2006

Summary Bacteroides compound transposons encoding erm resistance are highly homologous but previous studies have shown some divergence of Tn4551. Results presented here describe a novel Tn 4551 streptomycin‐resistance gene, aadS, that was phenotypically silent in wild‐type Bacteroides. However, aadS expression could be activated by a trans‐acting chromosomal mutation. The aadS‐encoded peptide displayed significant homology to Gram‐positive streptomycin‐dependent adenyltransferases, and enzymatic analysis confirmed the production of this activity. Examination of the nucleotide sequence showed that 200 bp upstream of aadS, the DNA base composition changed abruptly from 31% G+C to 48% G+C. These two regions were demarcated by a DNA sequence with homology to the recombination hot spots reported for Tn21 and the Bacteroides ermFU gene and to sequences at the ends of the chromosomal Bacteroides conjugal element, XBU4422.
The role of integration host factor In gene expression in Escherichia coli
Authors: Freundlich M. , Ramani N. , Mathew E. , Sirko A. , Tsui P. 
Published: October 2006

SummaryIntegration host factor is a sequence‐specific, histone‐like, multifunctional DNA‐binding and ‐bending protein of Escherichia coli. The characterization and functional analysis of this protein has been done mainly in bacteriophage λ and other mobile genetic elements. Less is known concerning the role of integration host factor (IHF) in E. coli, although it has been implicated in a number of processes in this organism including DNA replication, site‐specific recombination, and gene expression. This review presents recent work which suggests that IHF alters the activity of an unusually large number of operons in E. coli. We discuss the possible physiological relevance of the involvement of IHF in gene expression and the hypothesis that IHF is a member of a class of functionally redundant proteins that participate in chromosome structure and multiple processes involving DNA.
Mono‐ and bi‐phasic Salmonella typhi: genetic homogeneity and distinguishing characteristics
Authors: Moshitch Sharon , Doll Linda , Rubinfeld Ben‐Zion , Stocker Bruce A. D. , Schoolnik Gary K. , Gafni Yedidya , Frankel Gad 
Published: October 2006

SummarySeveral lines of evidence indicate a relatively low genetic heterogeneity in the natural Salmonella typhi population. However, some S. typhi isolates found in Indonesia express, instead of the usual fliC‐d flagellin gene, a different flagellar gene fliC‐j. In addition, Indonesian strains may have a second flagellar antigen fliC‐z66. We have previously suggested, on the basis of the flagellar antigen constitution, that S. typhi evolved in an isolated human population in Indonesia. In order to test this hypothesis, we have gathered S. typhi isolates from around the world and tested the genetic heterogeneity among them. In general, polymorphism was greater in isolates from the Far East, as was indicated by Southern hybridizations with rDNA and fliC DNA probes. Gene fliC‐j was not found in S. typhi isolates, other than those from Indonesia. However, the one‐clone origin of S. typhi was indicated by a common DNA fingerprint pattern and by the occurrence, in the 5′ end region of the fliC gene, of 10 scattered nucleotides that differ from the corresponding 10 nucleotides in other fliC alleles studied. These nucleotides were present in all isolates tested but did not change the amino acid sequence of the flagellin polypeptide.
Recombination between genes encoding major outer surface proteins A and B of Borrelia burgdorferi
Authors: Rosa Patricia A. , Schwan Tom , Hogan Daniel 
Published: October 2006

Summary Borrelia burgdorferi causes Lyme disease, a multisystem illness that can persist in humans for many years. We describe recombination between homologous genes encoding the major outer surface proteins (Osps) A and B of B. burgdorferi which both deletes osp gene sequences and creates chimaeric gene fusions. Recombinant osp genes occur in multiple strains and encode unique proteins that lack some characteristic Osp epitopes. Antigenic variation in Osp through recombination may be relevant to the persistence of B. burgdorferi in an infected host, and has important implications for the utility of OspA and OspB as diagnostic or vaccine candidates for Lyme disease. We also describe Osp variation arising from nonsense mutations and sequence divergence, which may also represent significant sources of Osp polymorphism.
Book Reviews
Authors: Lambert Kenneth 
Published: October 2006

The Freud/Jung Letters. The Correspondence between Sigmund Freud and C. G. Jung. McGuire, William (Ed.). Trs. by Ralph Manheim and R. C. F. HullFordham, M., Gordon, R., Hubback, J., Lambert, K. and Williams, M. Analytical psychology: A modern science. The library of analytical psychology, vol. 1Weaver, Rix. The old wise woman. A study of active imaginationAigrisse, Gilberte. Psychogènese d'un poème: La route du sel (Roger Bodart)Allen, David. The fear of looking or Scopophilic‐exhibitionistic conflictsReitenback, Hendrik M. (Ed.). The analytic situationLuria, A. R. The man with a shattered world. The history of a brain wound. Trans. from the Russan by Lynn SolotaroffHartmann, Ernest L. The functions of sleepBenthall, Jonathan (Ed): The limits of human nature
Reviews
Authors: Lambert Kenneth 
Published: October 2006

Frey‐Rohn, Liliane, From Freud to Jung: a comparative study of the psychology of the unconscious.Hillman, James. Re‐visioning psychology.Wilhelm, Helmut. Change: eight lectures on the I Ching.Pincus, Lily. Death and the family: the importance of mourning. PantheonParkes, Colin Murray. Bereavement: studies of grief in adult life.Eisenstein, Samuel A. Boarding the ship of death.Henderson, James L. A bridge across time.