摘要:

SummaryA 383bp segment of the gene coding for the 65kD mycobacterial antigens from Mycobacterium tuberculosis, Mycobacterium bovis, Mycobacterium avium, Mycobacterium paratuberculosis, and Mycobacterium fortuitum was amplified using Tag polymerase and synthetic oligonucleotide primers and the amplified DNAs from four of these species were compared by nucleotide sequencing. Although the gene segments from these species showed considerable similarity, oligonucleotide probes which could distinguish M. tuberculosis/M. bovis, M. avium/M. paratuberculosis and M. fortuitum could be identified. Samples containing 106human cells and serial dilutions of a suspension of intact mycobacteria were prepared, DNA was extracted, the segment of the mycobacterial DNA sequence amplified, and the amplified DNA hybridized with oligonucleotide probes. In two independent experiments, this procedure permitted the detection and identification of less than 100 mycobacteria in the original sample. These results suggest that this approach may prove useful in the early diagnosis of mycobacterial infection.

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00233.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe translational initiation rates directed by the translational initiation regions (TIRs) of theatpB, atpH, atpAandatpGgenes of Escherichia coli were investigated usinglacZfusions present on plasmids as well as integrated into the chromosome. This was the first investigation of the translational efficiency of theatpBgene, whose unfused product (subunit a) can be toxic to the cell. The specific mRNA levels, rates ofin vivoprotein synthesis and β‐galactosidase activities encoded by theatp:: lacZfusions were compared in order to obtain valid estimates of relative translation rates. The results indicate that in theE. coli atpoperon, translation directed by theatpB, atpHandatpGTIRs is less efficient than that directed by theatpATIR, and are thus consistent with earlier measurements of directatpgene expression. Initiation is, however, to differing extents, controlled by coupling to the translation of upstream neighbours. There is particularly tight coupling betweenatpHandatpA.Increasing the distance between these two genes whilst maintaining the originalatpATIR structure decreased the degree of coupling. The influence of manipulations of theatpGTIR structure upon translational efficiency was quantitatively more pronounced when theatpGfusions were present as a single copy per chromosome. This is likely to be related to the mRNA binding characteristics of 30S ribosomal subunits and/or to the influence of other (trans‐acting) factors. The control of independent and coupled initiation at theatpTIRs is discussed in relation to mRNA structure and possibleCiSand trans regulatory pheno

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00234.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe gene encoding cytotoxin (ctx) was cloned fromPseudomonas aeruginosa158 and the nucleotide sequence was determined. The structural gene ofctxencodes the procytotoxin of 286 amino acid residues with a molecular mass of 31681 Daltons. Procytotoxin was activated by removal of 20 amino acid residues from theCterminus with trypsin. The clonedctxgene was not expressed in either anEscherichia colistrain or a cytotoxin non‐producing strain ofP. aeruginosa.An expression system for thectxgene was constructed by placing the structural gene ofctxdownstream oftacpromoter on a broad host‐range vector plas

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00235.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryIn enteric bacteria, the expression of many genes encoding various anaerobic electron transfer functions is controlled by FNR, the product of the autoregulatedfnrgene. FNR is structurally and functionally homologous to CAP, the catabolite gene activator protein, and increased FNR production strongly stimulates transcription of its target genes. By analysis of RNA producedin vivothe promoters of four FNR‐dependent genes were localized and shown to display a common arrangement. A 22bp dyad symmetry was found about 30 nucleotides upstream of the transcriptional startpoints and a similar sequence was shown to overlap the site of transcription initiation in the negatively controlledfnrgene. The consensus sequence for the half site recognized by FNR (AAA‐TTGAT) is only slightly different from that of CAP (AA‐TGTGA). Studies with two mutantfrdpromoters fromEscherichia coli, displaying altered regulation and FNR response, provided additional evidence for recognition of this sequence b

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00236.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryTwo nodulation regions from the symbiotic plasmid (pSym) ofRhizobium phaseoilCE‐3 were identified. The two regions were contained in overlapping cosmids pSM927 and pSM991. These cosmids, in aR phaseolipSym‐cured strain background, induced ineffective nodules onPhaseolus vulgarisroots.Transconjugants ofRhizobium melilotiharbouring pSM991 induced nodule‐like structures on bean roots, suggesting that this cosmid contains host‐range determinants.Analysis of deletions and insertional mutations in the sequences of pSM991 indicated that the genes responsible for the induction and development of nodules inP. vulgarisare organized in two regions 20kb apart. One region, located in a 6.8kbEco RIfragment, includes the commonnodABCgenes. The other region, located in a 3.5kbEcoRIfragment, contains information required for host‐range dete

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00237.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe nucleotide sequence of a 2.4 kbDral‐EcoRVfragment of pColD‐CA23 DNA was determined. The segment of DNA contained the colicin D structural gene (cda) and the colicin D immunity gene (cdi). From the nucleotide sequence it was deduced that colicin D had a molecular weight of 74683D and that the immunity protein had a molecular weight of 10057D. The amino‐terminal portion of colicin D was found to be 96% homologous with the same region of colicin B. Both colicins share the same cell‐surface receptor, FepA, and require the TonB protein for uptake. A putative TonB box pentapeptide sequence was identified in the amino terminus of the colicin D protein sequence. Since colicin D inhibits protein synthesis, it was unexpected that no homology was found between the carboxy‐terminal part of this colicin and that of the protein synthesis inhibiting colicin E3 and cloacin DF13. This could indicate that colicin D does not function in the same manner as the latter two bacteriocins. The observed homology with colicin B supports the domain structure concept of colicin organization. The structural organization of the colicin operon is discussed. The extensive amino‐terminal homology between colicins D and B, and the strong carboxy‐terminal homology between colicins B, A, and N suggest an evolutionary assembly of colicin genes from a few DNA fragments which encode the functional domains responsible for colicin activi

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00238.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryA gene,pcnB, affecting the copy number of ColE1‐related plasmids has been cloned and mapped to 3.6 min on theEscherichia colichromosome betweenpanDandfhu.The gene encodes a previously un‐described 48 kD protein. Several independently isolated mutants exhibiting the same phenotye, reduced copy number, have been shown to be p

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00239.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryWe describe the construction of an RFLP‐based genetic map of the white rot fungusPhanerochaete chrysosporiumME446. The map is deduced from the allele distributions of 38 RFLP markers in a test set of 53 meiotically derived haploid recombinants of this strain. The map includes a cellulase gene, a mating‐type locus and a family of lignin peroxidase (and related) genes that are arranged in two unlinked clust

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00240.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryHaploid recombinant progeny ofPhanerochaete chrysosporiumME446, genome compositions of which had been defined by RFLP‐mapping, vary in their idiophasic behaviour. This allowed us to formulate a model of the sequence of idiophasic activities. One component of this variation, the amount of lignin peroxidase activity, is independent of the allele distributions of the lignin peroxidase gene clusters, but correlates with the allele distribution of another locus. This locus appears to control the spread of the lignin peroxidase‐active state within the idiophasic mycelial mat and may be the mating‐type locus. The successful determination of linkage relied on analysis of chromosome intervals rather than linkage to single markers; this approach should be generally useful for analysing quantitative characters by RFLP ma

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00241.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryThe expression ofEscherichia colitype 1 fimbriae is phase‐variable i.e. the bacterial cell is either fimbriated or non‐fimbriated. The transition from one state to the other is caused by the change in configuration of an invertible DNA segment harbouring the promoter of thefimAgene. The position of this phase switch is controlled by two proteins, FimB and FimE, which mediate an ‘on’ or ‘off’ configuration of the switch, respectively. In this study, we have investigated how these proteins control the switch by means offim‐lacfusions on low‐copy‐number plasmids. It was found, by intransandciscomplementation, that the ratio offimBtofimEand the total concentration of the gene products determine the configuration of the switch as well as the frequency of phase switching. It was also shown that transcription occurs from the promoter located at the phase switch when this is in the ‘off’ configuration. This suggests a regulatory mechanism, since the resulting transcript would be anti‐sen

ISSN:0950-382X    

DOI:10.1111/j.1365-2958.1989.tb00242.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY