bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of DNA probes identifying restriction‐fragment‐length polymorphisms to examine the Mycobacterium avium complex
Authors: McFadden J. J. , Butcher P. D. , Thompson J. , Chiodini R. , Hermon‐Taylor J. 
Published: October 2006

SummaryDNA probes were used to identify restriction‐fragment‐length polymorphisms (RFLPs) in DNA samples, demonstrating that the Mycobacterium avium complex could be clearly divided Into M. avium and Mycobacterium intracellulare strains. Less than 2% DNA base substitution was found between M. avium strains, whereas the M. intracellulare strains had greater than 15% base substitution. The Johne's disease bacillus, Mycobacterium paratubercuiosis (American type strain), was found to be distinguishable from the M. avium complex serotypes examined. Strain 18 was found to be identical to M. avium. The rat leprosy bacillus, Mycobacterium lepraemurium, was found to be very closely related, but not identical, to M. avium.
Effects of deletions in the spacer region of the rrnB operon on the transcription of the large ribosomal RNAs from Escherichia coli
Authors: Szymkowiak C. , Wagner R. 
Published: October 2006

SummaryA series of deletions was constructed within the spacer region of the genes for the 16S and 23S RNA on plasmids bearing the rrnB operon. The accumulation and synthesis rates for the 16S and 23S RNAs were determined from normal growing cells and maxicells after transformation with the mutated plasmids. A marked difference In the transcription efficiency of the plasmid‐encoded ribosomal 16S and 23S RNAs was observed with cells carrying plasmids, where a sequence motif analogous to the antitermination recognition sequence (Box A) had been deleted. The overall synthesis rate of ribosomal RNAs of such cells was not altered, however, indicating that the difference in transcription rates from the plasmid genes is compensated by altered transcription rates of the corresponding chromosomal genes. In addition, the accumulation of various tRNA species encoded on rRNA operons and non rRNA operons was quantitated and compared. From these results we infer that the regulation of ribosomal RNA transcription does not only occur at the promoter sites but sequence regions possibly involved in antitermination within the operon are crucial for a coordinated synthesis of all ribosomal RNAs.
A plasmid‐encoded gas vesicle protein gene in a halophilic archaebacterium
Authors: DasSarma S. , Damerval T. , Jones J. G. , Marsac N. Tandeau de 
Published: October 2006

SummaryThe halophilic archaebacterium, Halobacterium halobium, displays spontaneous and revertible genetic variability for the gas vesicle phenotype (Vac) at frequencies as high as 0.5 to 5%. To investigate the mechanism of these high‐frequency mutations, we have cloned a gas vesicle protein gene (gvpA) from the Vac+ wild‐type H. halobium strain, NRC‐1, and determined its nucleotide sequence, transcription start site, and genomic location. The gene sequence predicts that the gas vesicle protein has a molecular weight of 9156 and is relatively hydrophobic except for a hydrophilic C‐terminal region. Northern hybridization analysis shows that the gene is transcribed into a 350‐nucleotide mRNA, and primer extension analysis indicates that transcription begins 20 nucleotides upstream of the ATG start codon. Southern hybridization analysis shows that the gene is encoded by a large H. halobium plasmid. We discuss potential mechanisms for genetic variability of the Vac phenotype and identify sequences in the gvpA promoter region which may function as signals for transcription in H. halobium.
Expression of multiple types of N‐methyl Phe pili in Pseudomonas aeruginosa
Authors: Elleman T. C. , Peterson J. E. 
Published: October 2006

SummaryThe nature of pili synthesized by Pseudomonas aeruginosa when plasmid‐borne genes of homologous pilins from Bacteroides nodosus are Introduced as thermoregulated expression systems has been ascertained. Expression of B. nodosus pili inhibited the production of indigenous P. aeruginosa pili, and an organism harbouring pilin genes from two strains of B. nodosus produced two seroiogically distinct populations of pili on each cell. Simultaneous production of both Indigenous and foreign pili was achieved by partial induction of expression. Homogeneity in pilus structure suggests either that there is an exclusive specificity of Interaction between identical pilin subunits in pilus assembly, or that each pilus is produced from the translation products of a single messenger RNA molecule, with translation and pilus assembly closely coupled.
Use of TnphoA to enrich for extracellular enzyme mutants of Erwinia carotovora subspecies carotovora
Authors: Hinton J. C. D. , Salmond G. P. C. 
Published: October 2006

SummarySoft rot Erwinia species secrete a range of enzymes into the extracellular environment. Therefore, the genetically amenable Erwinia system is a useful model for the study of protein secretion by Gram‐negative bacteria. We have used a λ‐sensitive derivative of Erwinia carotovora subspecies carotovora (Ecc) and the transposon TnphoA, to isolate a range of extracellular enzyme mutants. The use of TnphoA provides an enrichment for extracellular enzyme mutants over other transposon‐based systems. In these mutants, the alkaline phosphatase activity of the hybrid protein Is found in the periplasm, and is under the control of the Ecc promoters. Three TnphoA‐induced extracellular enzyme mutants were studied in detail. One proved to be an enzyme structural gene mutant, whilst the other two appeared to be secretory mutants.
Identification and characterization of the transferrin receptor from Neisseria meningitidis
Authors: Schryvers A. B. , Morris L. J. 
Published: October 2006

SummaryExpression of the meningococcal transferrin receptor, detected by assay with human transferrin conjugated to peroxidase, was regulated by the level of iron in the medium. The transferrin receptor was identified by SDS‐PAGE and Western blot analysis, as a 71 000 molecular weight iron‐regulated outer membrane protein in Neisseria meningitidis B16B6. Growth studies with iron‐deficient cells and competition binding experiments demonstrated that the meningococcal receptor was species‐specific for human transferrin. Reciprocal competitive binding experiments and limited proteolysis of intact cells indicated that the transferrin and lactoferrin receptors are distinct.
Chromosomal mapping of the pel and cel genes in Erwinia chrysanthemi strain B374
Authors: Piecq M. , van Gijsegem F. , Schoonijans E. , Toussaint A. 
Published: October 2006

SummaryUsing the RP4::mini‐Mu in vivo cloning technique, van Gijsegem et al. (1985) isolated several pel and cel genes of Erwinia chrysanthemi (Ech) B374 strain. We have localized these genes on the Ech chromosome by co‐transfer mapping of Mud11734 insertion mutants and refined the map by co‐transposition analysis. This analysis has enabled us to identify another cel gene.
Nucleotide sequence and mutagenesis of the nifA gene from Azotobacter vinelandii
Authors: Bennett L. T. , Cannon F. , Dean D. R. 
Published: October 2006

SummaryThe nucleotide sequence of the nifA gene from Azotobacter vinelandii was determined. This gene encodes an Mr= 58100 polypeptide that shares significant sequence identity when compared to nifA‐encoded products from other organisms. Interspecies comparisons of nifA‐encoded products reveal that they all have a consensus ATP binding site and a consensus DNA binding site in highly conserved regions of the respective polypeptides. The nifA gene immediately precedes the nifB‐nifQ gene region but is unlinked to the major nif gene cluster from A. vinelandii. A potential regulatory gene precedes and is apparently cotranscribed with nifA. Mutant strains that have a deletion or a deletion plus an insertion within nifA are incapable of diazotrophic growth and they fail to accumulate nitrogenase structural gene products.
Transcription of a Rhizobium ieguminosarum biovar phaseoli gene needed for melanin synthesis is activated by nifA of Rhizobium and Klebsiella pneumoniae
Authors: Hawkins F. K. L. , Johnston A. W. B. 
Published: October 2006

SummaryThe Rhizobium leguminosarum biovar phaseoli symbiotic plasmid pRP2JI carries a gene, melA, specifying the enzyme tyrosinase, which is responsible for the production of the pigment melanin in these bacteria. Transcription of melA is activated by the nifA gene of Rhizobium and, when the cloned melA gene is transferred to Escherichia coli, melA is expressed if the recipients contain nifA gene of Klebsiella pneumoniae. This nifA‐dependent activation was temperature sensitive and required the ntrA gene. The cloned nifA gene of K. pneumoniae, when transferred to a nifA mutant of Rhizobium phaseoli biovar phaseoli, corrected the Mer− but not the Fix− phenotype. nifA of R. leguminosarum biovar phaseoli activated melA at higher levels in cells grown in low concentrations of oxygen. Also, nifA of fl. leguminosarum biovar phaseoli activated nifH of K. pneumoniae in Escherichia coli cells grown In low‐oxygen concentrations.
Regulation of the virC and virD promoters of pTiC58 by the ros chromosomal mutation of Agrobacterium tumefaciens
Authors: Tait R. C. , Kado C. I. 
Published: October 2006

SummaryThe virC and virD operons of the virulence region of the Ti plasmid are highly regulated, requiring a transcriptional regulator that is encoded by virG and is activated by the product of virA and plant phenolics such as acetosyringone. Full expression of virC and virD of octopine and nopaline Ti plasmids is also obtained by a mutation in the ros gene of the Agrobacterium tumefaciens chromosome. S1‐nuclease analysis, in vitro transcription, and DNase I protection experiments with A. tumefaciens RNA polymerase revealed virD promoters tandemly arranged, both of which are functional in the Ros mutant, while only one is functional in the presence of acetosyringone. A third (overlapping) promoter appears to be responsible for transcription of virC. Expression of virC and virD appears to be modulated by factors within the bacterium by means of a mechanism that is independent of factors produced during infection of the host plant.
Characterization of the human transferrin and lactoferrin receptors in Haemophilus influenzae
Authors: Schryvers A. B. 
Published: October 2006

SummaryThe expression of human transferrin and lactoferrin binding activity in Haemophilus influenzae, detected by a binding assay using human transferrin or lactoferrin conjugated to peroxidase, was regulated by the level of available iron in the medium. Transferrin binding activity was present in all H. influenzae isolates tested but not detected in other Haemophilus species or in species of Pasteurella or Actinobacillus. Lactoferrin binding activity was only detected in all H. influenzae isolates tested. The transferrin and lactoferrin receptors were shown to be specific for the respective human proteins by means of a competition binding assay. Competition binding assays also showed that iron‐loaded transferrin was more effective at blocking the transferrin receptor than apotransferrin, but no differences in receptor blocking were observed between iron‐loaded lactoferrin and apolactoferrin.
The expression of mutant pilins in Pseudomonas aeruginosa: fifth position glutamate affects pilin methylation
Authors: Pasloske B. L. , Paranchych W. 
Published: October 2006

SummaryThe expression within Pseudomonas aeruginosa PAO1 of three mutant pilin genes from P. aeruginosa PAK was studied to determine their effects on pilin stability, translocation into the membrane, leader peptide removal, and methylation of the mature N‐terminal phenylalanine. The results revealed that a deletion of 4 or 8 amino acids within the immediate N‐terminus of pilin had deleterious effects upon leader peptide cleavage. In addition, while the 4‐amino‐acid deletion did not affect pilin partitioning into the membrane, the 8‐amino‐acid deletion decreased the amount of pilin found within the membrane fraction. Of considerable interest was the finding that the mutation within the mature pitin of the glutamate at position 5 to a lysine did not prevent leader peptide removal but did inhibit the methylation of the N‐terminal phenylalanine.
The nirB promoter of Escherichia coli: location of nucleotide sequences essential for regulation by oxygen, the FNR protein and nitrite
Authors: Jayaraman P.‐S. , Gaston K. L. , Cole J. A. , Busby S. J. W. 
Published: October 2006

SummaryUsing recombinant DNA techniques, nested deletions have been made upstream of the Escherichia coli nirB transcription start site and their effects on the regulation of nirB promoter activity have been measured. Nucleotide sequences downstream of −73 are sufficient for FNR‐dependent induction of activity by anaerobic growth conditions. However, nucleotide sequences between −87 and −149 are essential for further induction by nitrite in the growth medium. The nucleotide sequence at the galP1 CRP binding site located from −31 to −52 displays some similarities with the same region at the nirB promoter. When the galP1 sequence from −30 to −54 was replaced by the corresponding nirB sequence, expression from galP1 became inducible by FNR under anaerobic growth conditions.
Cloning of a novel pilin‐like gene from Bordetella pertussis: homology to the fim2 gene
Authors: Pedroni P. , Riboli B. , de Ferra F. , Grandi G. , Toma S. , Aricò B. , Rappuoli R. 
Published: October 2006

SummaryA search for pilin genes in a Bordetella pertussis (Bp) genomic library has led to the identification of several clones which hybridize to synthetic oligonucleotides with sequences derived from amino acid sequences of Bp fimbrial subunits. One of these clones (corresponding to a gene we have named fimX) contains an open reading frame encoding a protein with a molecular weight of about 20 kD and a sequence similar but not identical to the fimbrial subunit fim2 and to other fimbrial protein sequences. In this communication we present the cloning and nucleotide sequence of the fimX gene and its homology to the fim2 gene. A genomic analysis on the positional relationship between the two genes is also presented.
Topology of membrane insertion in vitro and plasma membrane assembly in vivo of the yeast arginine permease
Authors: Ahmad M. , Bussey H. 
Published: October 2006

SummaryWe have examined the topology of the yeast arginine permease, a plasma‐membrane protein with multiple membrane‐spanning domains. Using fusions of the permease with the glycosylatable secreted yeast protein, acid phosphatase, we identified membrane‐spanning sequences that can translocate adjacent acid phosphatase across the membrane of the endoplasmicreticulum (ER), as measured by in vitro glycosylation. Examination for the presence or absence ofglycosylation in a systematic series of such fusions gave an internally consistent model for the lumenat orcytoplasmic disposition of the acid phosphatase reporter, defining the topology of the permease. The phenotypes of a further set of arginine permease gene fusions with portions of the gene for the secreted protein, killer toxin, suggest that the pathways of export of membrane and secreted proteins need not be functionally distinct.
Nucleotide sequence analysis of 2″‐aminoglycoside nucleotidyl‐transferase ANT(2″) from Tn4000: its relationship with AAD(3″) and impact on Tn21 evolution
Authors: Schmidt F. R. J. , Nücken E. J. , Henschke R. B. 
Published: October 2006

SummaryAminoglycoside 2″‐O‐nucleotidyltransferase (AAD(2″)) mediates bacterial resistance to dibekacin, gentamicin, kanamycin, sisomicin and tobramycin. Its coding sequence, aadB, is part of Tn21‐related transposon, Tn4000. Nucleotide sequence analysis revealed the presence of an open reading frame capable of specifying a protein of 177 amino acids with a calculated molecular weight of 21240. The predicted amino acid sequence revealed up to 27% homology to that of three nucleotidyltransferases of type AAD(3″), which are widely distributed among Gram‐negatives, and to the AAD(9) from Staphylococcus aureus transposon Tn554. The regions flanking aadB suggest that its insertion into Tn21 arose from a site‐specific recombination event adjacent to the aadA gene.
Comparison of the chemotactic behaviour of Rhizobium leguminosarum with and without the nodulation plasmid
Authors: Armitage J. P. , Gallagher A. , Johnston A. W. B. 
Published: October 2006

SummaryThe chemotactic behaviour of a strain of Rhizobium leguminosarum biovar viciae was investigated. The flavanoids apigenin and naringenin, inducers of transcription of the nodulation (nod) genes, were both potent attractants but hesperitin, another flavone nod gene inducer, was not. The response of strains containing the Sym plasmid pRL1JI to apigenin and naringenin was significantly greater than the response of a strain cured of the plasmid, although both strains gave a positive response. Addition of the flavanol kaempferol, an antagonist of nod gene induction, had no detectable effect on the chemotactic response to naringenin or aplgenin, but was itself found to be an attractant. The attractant response to a variety of amino acids and sugars was not affected by the presence of the Sym plasmid. Homoserine, the most abundant nitrogenous compound in legume exudates, was also found to be an attractant. However, although the Sym plasmid is required for the biovar to metabolize homoserine as a carbon source, it was not required for the chemotactic response. A group of membrane proteins showed increased methylation in response to stimulation with serine. There was no measurable change in methylation after stimulation with apigenin.
Probing the surface of Neisseria gonorrhoeae: immunoelectron microscopic studies to localize cyanogen bromide fragment 2 in gonococcal pili
Authors: Robinson E. N. , Clemens C. M. , Schoolnik G. K. , McGee Z. A. 
Published: October 2006

SummaryCommon epitopes accessible to antibody on purified macromolecules or structurally altered gonococci may not be accessible to antibody when those macro‐molecules are in their native state on the surface of intact organisms. To determine the immunologic accessibility of cyanogen bromide fragment 2 (CNBr2), a portion of the gonococcal pilin molecule that is common to all gonococcal strains on the surface of viable gonococci, probes composed of specific CNBr2 antibodies linked to gold spheres were manufactured. When whole piliated gonococci were exposed to these anti‐CNBr2 immunological probes and examined using transmission electron microscopy, no significant marking of native pili was evident. These probes, however, detected CNBr2 in purified form. The epitopes encompassed within the CNBr2 portion of pili appear to be inaccessible to anti‐CNBr2 probes within native gonococcal pili.
Construction, transfer and properties of a novel temperature‐sensitive integrable plasmid for genomic analysis of Staphyiococcus aureus
Authors: Luchansky J. B. , Benson A. K. , Atherly A. G. 
Published: October 2006

SummaryAs an alternative approach to genetic transfer and analysis, a novel integrable plasmid system was developed that should prove useful for mapping and cloning various genes in Staphylococcus aureus and other Gram‐positive bacteria. The use of a restriction‐deficient recipient strain and an improved protocol for protoplast plasmid transformation facilitated direct cloning of a recombinant plasmid (pPQ126) in S. aureus NCTC 8325‐4. Plasmid pPQ126 (13.6 kb) is a novel, temperature‐sensitive integrable plasmid containing genes encoding resistance to erythromycin and chloramphenicol (from plasmid pTV1ts), and resistance to gentamicin (from transposon Tn4001). When introduced into an appropriate recipient strain at the permissive temperature (30°C), pPQ126 replicates autonomously. Integration of pPQ126 is directed into homologous chromosomal target sequences (chromosomal insertions of Tn551 or Tn4001) by growing a population of cells containing autonomous pPQ126 in the presence of gentamicin, erythromycin, and chloramphenicol at 39°C (nonpermissive temperature). Elevated temperature both selects for and maintains pPQ126 as an integrated replicon. Integration of pPQ126 occurs at significantly reduced frequency in a recombination‐deficient host, and does not occur in the absence of host chromosomal homology. Integrated pPQ126 excises from the chromosome under permissive conditions (30°C), and excision results in derivatives of pPQ126 that harbour DNA of chromosomal origin.
Structural and functional analysis of the mini‐circle, a transposable element of Streptomyces coelicolor A3(2)
Authors: Henderson D. J. , Lydiate D. J. , Hopwood D. A. 
Published: October 2006

SummaryThe mini‐circle is a transposable element which is present in Streptomyces coelicolor A3(2) in both free circular and chromosomally integrated linear forms. The nucleotide sequences of the mini‐circle and its preferred site of integration in the Streptomyces lividans TK64 chromosome were determined. Three putative open reading frames were identified in the mini‐circle sequence. The mini‐circle does not appear to cause a target site duplication on transposition and does not have perfect terminal inverted repeats. The observed site‐specificity of the mini‐circle is not mediated by extensive homology between the element and the chromosomal integration site. Transposition of the mini‐circle into the S. lividans chromosome was demonstrated and found to be some two orders of magnitude less efficient than integration of the circular form of the element, suggesting that the circular form of the mini‐circle might be a normal intermediate in the transposition process.
Unique sequences in region VI of the flagellin gene of Salmonella typhi
Authors: Frankel G. , Newton S. M. C. , Schoolnik G. K. , Stocker B. A. D. 
Published: October 2006

SummaryThe HI (now renamed fliC; lino et al., 1988) alleles specifying antigenically different Salmonella flagellins are identical at their ends but differ greatly towards the middle, where there are two hypervariable segments (regions IV and VI). The flagellar antigen, d, of Salmonella typhi, is found also as phase‐1 antigen in many other Saimonella species. We cloned the H1‐d gene of a strain of S. typhi and determined the nucleotide sequence of its two hypervariable regions. Comparison with gene H1‐d of Salmonella muenchen showed substantial differences in region VI: four scattered amino acid differences and ten adjacent amino acids in the inferred S. typhi sequence, all of which differ from the corresponding nine amino acids in the S. muenchen sequence. The results of polymerase chain reaction amplification indicated the presence of the S. typhi version in all of 18 additional S. typhi strains and the presence of the S. muenchen version in all four non‐S. typhi species with flagellar antigen d. The difference in amino acid sequence in segment VI may be responsible for the minor serological differences between antigens d of S. typhi and antigen d of S. muenchen.
An electrophoretic karyotype and assignment of ribosomal genes to resolved chromosomes of Pneumocystis carinii
Authors: Yoganathan T. , Lin H. , Buck G. A. 
Published: October 2006

SummaryPulsed‐field gel electrophoresis was used to generate a molecular karyotype of chromosomes from the opportunistic AIDS pathogen, Pneumocystis carinii. P. carinii cysts and trophozoites were isolated from immunosuppressed rats, lysed in situ in agarose blocks, and subjected to orthogonal‐field gel electrophoresis (OFAGE) and contour‐clamped homogeneous‐field gel electrophoresis (CHEF). OFAGE and CHEF gels resolved, respectively, 16 or 20 chromosome bands ranging in size from 0.32‐1.5 megabase pairs. Summation of the estimated sizes of these chromosomes suggested a total genome complexity for P. carinii of 8‐16 megabase pairs. Homologous probes for the genes encoding the 18S, 5.8S, and 5S ribosomal RNAs were hybridized to filter blots of the pulsed‐field gels to map these genes to specific P. carinii chromosomes.