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  • Agrobacterium  (6)
  • Springer  (6)
  • 1
    Electronic Resource
    Electronic Resource
    Oxygen-dependent desulphation of monomethyl sulphate by Agrobacterium sp. M3C (1990)
    Springer
    Biodegradation 1 (1990), S. 229-241 
    Details
    ISSN: 1572-9729
    Keywords: Agrobacterium ; desulphation ; monomethyl sulphate ; oxygenase ; methylotrophy ; sulphate ester degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Agrobacterium sp. M3C, previously isolated from canal-water for its ability to grow on monomethyl sulphate, degraded this ester with stoichiometric liberation of inorganic sulphate. In contrast with the biodegradation of monomethyl sulphate in Hyphomicrobium sp., and of other longer-chain alkyl sulphates in Pseudomonas spp., the pathway in Agrobacterium appeared not to involve a sulphatase enzyme capable of catalysing ester-bond hydrolysis. No such sulphatase was detectable under a range of conditions of bacterial culture, or using various methods for preparing cell-extracts, or different assay conditions. There was no incorporation of 18O-label from H2 18O into the liberated inorganic sulphate. No methanol was detectable during biodegradation, and the organism was incapable of growth on methanol, and did not produce methanol dehydrogenase activity when grown on monomethyl sulphate. Tracer studies using mono[14C]-methyl sulphate indicated that formate serine and glycine were produced during the biodegradation. The presence of these amino acids, together with high activity of hydroxypyruvate reductase, indicated the operation of the serine pathway common in methylotrophs. Use of an oxygen electrode in conjunction with monomethyl[35S]sulphate showed that release of 35SO4 2- was dependent on availability of O2, and that there was equimolar stoichiometry among monomethyl sulphate degraded, O2 consumed and 35SO4 2- released. A proposed pathway for the degradation involved an initial mono-oxygenation to methanediol monosulphate with subsequent elimination of SO4 2- and concomitant formation of formaldehyde. The pathway was compared with degradation mechanisms for other C1 compounds and for other sulphate esters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00119760
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of right terminal repeat deletion on the oncogenicity of the T-Region of pTiT37 (1985)
    Springer
    Plant molecular biology 5 (1985), S. 3-11 
    Details
    ISSN: 1573-5028
    Keywords: Agrobacterium ; tumorigenicity ; border repeats ; tmr locus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A modified pTiT37 plasmid was constructed by deleting a 103 base fragment between an AhaIII and a Bc/I site. This fragment, located to the right of the nopaline synthase gene contains the right terminal 25 base pair repeat sequence which defines the right limit of the T-Region. The effect of this deletion was determined on a number of host plants. In contrast to previous reports, the deletion does not destroy tumorigenicity on all plant species. It had no effect on tumorigenicity when Linum usitatissimum was used as the test species and an attenuating effect when Kalanchoë tubiflora was used. Only when Nicotiana tabacum was used did the mutant appear avirulent. We propose from these data and the phenotype of those tumours that form, that a pseudo border located in the 3′ untranslated region of the ipt locus has been used to provide the right hand limit of the T-Region in the absence of the normal border.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00017868
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  • 3
    Electronic Resource
    Electronic Resource
    Positive-negative selection and T-DNA stability in Arabidopsis transformation (1999)
    Springer
    Plant molecular biology 39 (1999), S. 83-93 
    Details
    ISSN: 1573-5028
    Keywords: Arabidopsis ; Agrobacterium ; T-DNA ; CodA ; positive-negative selection ; recombination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have analysed the application of positive-negative selection for the selection of homologous recombination interactions between the chromosome and a T-DNA molecule after transformation of plant cells. Two different genomic loci in a cell suspension of Arabidopsis thaliana were chosen to study gene targeting events. One was the chalcone synthase (CHS) gene present as a single copy and the second an hemizygous chromosomally inserted T-DNA containing the hpt gene, conferring resistance to hygromycin, flanked by CHS sequences. The target lines were transformed with replacement-type T-DNA vectors which contained a positive selectable marker flanked by the regions of the CHS gene and a negative selectable marker to counter-select random insertions. As negative marker we used the Escherichia coli codA gene encoding cytosine deaminase, conferring upon the cells sensitivity to 5-flourocytosine (5-FC). Doubly selected transformants represent 1–4% of the primary transformed cells. Targeting events were not found at the chalcone synthase locus nor at the artificial hpt locus in a total of 4379 doubly selected calli, corresponding to at least 109 475 individual primary transformants. We show by PCR and Southern analysis that the 5-FC resistance in the majority of these cells is associated with substantial deletions of the T-DNA molecule from the right-border end.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006192225464
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  • 4
    Electronic Resource
    Electronic Resource
    Nopaline causes a conformational change in the NocR regulatory protein-nocR promoter complex of Agrobacterium tumefaciens Ti plasmid pTiT37 (1993)
    Springer
    Molecular genetics and genomics 241 (1993), S. 65-72 
    Details
    ISSN: 1617-4623
    Keywords: Agrobacterium ; Nopaline ; Gene regulation ; Protein-DNA interaction ; DNA topology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nocR gene of Agrobacterium tumefaciens Ti plasmid pTiT37 is the regulatory gene of the nopaline catabolism (noc) operon of pTiT37. We have cloned and sequenced nocR, which encodes a DNA-binding protein. The deduced amino acid sequence is similar to those of members of the LysR family of prokaryotic activator proteins. Gel retardation experiments demonstrated that the NocR protein binds to the nocR promoter in both the presence and absence of nopaline. The increased mobility of the complex and alterations in the DNase I footprints revealed a nopaline-induced conformational change in the NocR-DNA complex. Sequence analysis of the NocR binding site indicated the presence immediately downstream of the −10 sequence of the nocR promoter of a 12 by putative operator overlapping a consensus gyrase recognition sequence and an 18 by long alternating purine-pyrimidine sequence. These results suggest that nopaline-induced alterations in the NocR protein-nocR promoter complex might control gene expression in the noc operon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00280202
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  • 5
    Electronic Resource
    Electronic Resource
    The NocR repressor-activator protein regulates expression of the nocB and nocR genes of Agrobacterium tumefaciens (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 367-373 
    Details
    ISSN: 1617-4623
    Keywords: Agrobacterium ; Nopaline ; Repressor Activator ; LysR family
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The NocR protein of Agrobacterium tumefaciens was found to regulate expression of the divergently transcribed nocB and nocR genes of the pTiT37 nopaline catabolism (noc) region. Experiments using the firefly luciferase (luc) gene as reporter demonstrated that NocR represses and activates transcription from the nocB promoter in the absence and presence of nopaline, respectively. NocR also negatively autoregulates its own synthesis irrespective of the presence of nopaline. Regulation of expression of both nocB and nocR is mediated by binding of the NocR protein to the nocR promoter. A 12 by symmetrical sequence, which lies 3 by downstream of the −10 hexamer of the nocR promoter, was confirmed to be essential for binding of the NocR protein. Functional localization of the nocB and nocR promoters verified that they do not overlap at all, and that the interrupted dyad, at which NocR binds, is 137 by upstream of the regulated nocB promoter. The in vivo and in vitro results described here and those published previously suggest that a novel type of regulatory mechanism, which may involve changes in DNA topology, controls gene expression in the noc operon of pTiT37.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00286688
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  • 6
    Electronic Resource
    Electronic Resource
    Characterisation of the T-region of the SAP-type Ti-plasmid pTiAT181: identification of a gene involved in SAP synthesis (1986)
    Springer
    Molecular genetics and genomics 202 (1986), S. 62-67 
    Details
    ISSN: 1617-4623
    Keywords: Agrobacterium ; Succinamopine ; T-DNA ; AT181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The T-region of pTiAT181, a SAP(succinamopine)-type Ti-plasmid, is described and is found to be similar to that of the nopaline-type pTiT37. The two major differences are a deletion of 2.9 kb inside the left hand end of pTiAT181, and a right hand region comprised of DNA specific to pTiAT181. This novel DNA was shown by its transfer to plants using a binary vector, to encode an enzyme involved in the synthesis of SAP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00330518
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