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1.
The gene of tryptophan 7-halogenase was isolated from the Pseudomonas aureofaciens ACN strain producing pyrrolnitrin, a chlorocontaining antibiotic, and sequenced. A high homology degree (over 95%) was established for the genes and the corresponding halogenases from P. aureofaciens ACN and P. fluorescens BL915. The tryptophan 7-halogenase gene was amplified by PCR, and the corresponding enzyme was expressed in Escherichia coli cells using the pBSII SK+ vector. 相似文献
2.
Oscillatory behaviour in the tryptophan operon of an Escherichia coli mutant strain lacking the enzyme-inhibition regulatory mechanism has been observed by Bliss et al. but not confirmed by others. This behaviour could be important from the standpoint of synthetic biology, whose goals include the engineering of intracellular genetic oscillators. This work is devoted to investigating, from a mathematical modelling point of view, the possibility that the trp operon of the E. coli inhibition-free strain expresses cyclically. For that we extend a previously introduced model for the regulatory pathway of the tryptophan operon in Escherichia coli to account for the observed multiplicity and cooperativity of repressor binding sites. Thereafter we investigate the model dynamics using deterministic numeric solutions, stochastic simulations, and analytic studies. Our results suggest that a quasi-periodic behaviour could be observed in the trp operon expression level of single bacteria. 相似文献
3.
Corina Seibold Helge Schnerr Julia Rumpf Andrea Kunzendorf Catharina Hatscher Tobias Wage 《Biocatalysis and Biotransformation》2013,31(6):401-408
Regioselective halogenation of electron rich substrates is catalysed by flavin-dependent halogenases. Thienodolin produced by Streptomyces albogriseolus contains a chlorine atom in the 6-position of the indole ring system and is believed to be derived from tryptophan. Using the gene of the tryptophan 7-halogenase (PrnA) from the pyrrolnitrin biosynthetic gene cluster the gene for a tryptophan 6-halogenase was cloned, sequenced and heterologously overexpressed in Pseudomonas strains. In vitro activity of the purified enzyme could only be shown in a two-component enzyme system consisting of the halogenase, a flavin reductase, NADH, FAD and halide ions. The enzyme catalyses the regioselective chlorination and bromination of l- and d-tryptophan. In its native form the enzyme is probably a homodimer with a relative molecular mass of the subunits of 63 600 (including the His-tag). Transformation of the pyrrolnitrin producer Pseudomonas chlororaphis ACN with a plasmid containing the tryptophan 6-halogenase gene lead to the formation of the new aminopyrrolnitrin derivative 3-(2′-amino-4′-chlorophenyl) pyrrole. 相似文献
4.
Strain IC1270 of Enterobacter agglomerans has been previously described as a producer of a complex of chitinolytic enzymes and as an antagonist of many fungal phytopathogens
[Chernin et al. (1995) Appl. Env. Microbiol. 61:1720–1726]. Here we show that this strain also produces an antibiotic that
was purified by TLC and HPLC and identified by UV, IR, MS, and NMR analyses as pyrrolnitrin [3-chloro-4-(2′-nitro-3′-chlorophenyl)pyrrole].
The purified antibiotic is efficient against many phytopathogenic bacteria and fungi in vitro. This is the first piece of
evidence showing that pyrrolnitrin can be produced by bacteria other than Pseudomonas and that one bacterial strain can simultaneously produce chitinolytic enzymes and pyrrolnitrin. The possible role of a combination
of chitinases and pyrrolnitrin in antagonism is discussed. 相似文献
5.
Park JY Oh SA Anderson AJ Neiswender J Kim JC Kim YC 《Letters in applied microbiology》2011,52(5):532-537
Aims: To determine whether glucose in growth medium affects secondary metabolite production and biocontrol efficacy of Pseudomonas chlororaphis O6. Methods and Results: The secondary metabolites pyrrolnitrin and phenazines antagonize phytopathogenic fungi. The expression of the prnA gene encoding tryptophan halogenase, the first step in pyrrolnitrin biosynthesis, required the stationary‐phase sigma factor, RpoS. Mutations in rpoS and prnA in Ps. chlororaphis O6 eliminated antifungal activity against Rhizoctonia solani and Fusarium graminearum. Pyrrolnitrin production was reduced by glucose in growth media, whereas phenazine levels were increased. The efficacy of Ps. chlororaphis O6 in the biocontrol of tomato late blight was reduced by addition of glucose to the growth medium. Conclusions: Regulation by glucose of pyrrolnitrin production influenced the efficacy of the biocontrol of tomato leaf blight. Significance and Impact of the Study: The nutritional regulation of secondary metabolite production from a soil pseudomonad may account, at least in part, for the variability of biocontrol under field conditions. 相似文献
6.
Summary Batch and continuous culture studies have been carried out on a strain ofZ.mobilis (ZM6306) which can convert lactose directly to ethanol. Previous strain development has established that thelac operon encoded on the transposon Tn951 can be expressed inZ.mobilis. Using a medium containing 80 g/l glucose and 40 g/l lactose, it was found that strain ZM6306 could convert about 13 g/l lactose to 4 g/l ethanol and 6 g/l galactose in continuous culture. Further lactose conversion is likely with increased cell concentration using a cell recycle system. 相似文献
7.
Paul Gollnick 《Molecular microbiology》1994,11(6):991-997
8.
9.
Isolation of the novel regulatory mutants of the tryptophan biosynthetic system in Escherichia coli 总被引:6,自引:0,他引:6
Summary A novel type of tryptophan requiring mutants of Escherichia coli was isolated. The mutation maps between str and malA.These mutants, designated as trpS, have alterations in the regulation of the tryptophan operon. Neither derepression nor complete repression of the tryptophan biosynthetic enzymes was observed with this mutant. Dominance test shows that the trpS mutation is recessive to the wild type allele. TrpS mutant, therefore, is a type of super-repressed mutants distinct from i
s mutant in the lactose system of E. coli.It was found that the tryptophanyl-tRNA synthetase is specified by the trpS gene. This indicates that the transfer mechanism of tryptophan is related to repression of the tryptophan operon. 相似文献
10.
Richard P. Elander James A. Mabe Robert H. Hamill Marvin Gorman 《Applied and environmental microbiology》1968,16(5):753-758
Twenty-nine strains of Pseudomonas, classified as P. fluorescens biotype D or E or as P. multivorans, were examined for the production of pyrrolnitrin, an antifungal agent synthesized in P. aureofaciens. Eight strains were shown to produce pyrrolnitrin in shake-flask fermentation. Four cultures were from the multivorans taxon, and the remaining four were members of the fluorescens group. The antifungal agent produced in these strains was isolated and shown to be pyrrolnitrin by comparison with an authentic sample. The strains differed markedly with respect to the amount of pyrrolnitrin produced and in their utilization of exogenous tryptophan. Secondary metabolites, not related to pyrrolnitrin, were also examined and compared with those synthesized in P. aureofaciens. Marked differences were noted in both phenazine pigments and phenolic metabolites. The results of the study suggest that the production of pyrrolnitrin may be widespread in selected taxonomic groups of Pseudomonas. 相似文献
11.
12.
Some novel transcription attenuation mechanisms used by bacteria 总被引:2,自引:0,他引:2
13.
Hideaki Yukawa Yasurou Kurusu Mitsunobu Shimazu Masato Terasawa Akinori Ohta Isao Shibuya 《Bioscience, biotechnology, and biochemistry》2013,77(12):3619-3622
In an Escherichia coli K-12 strain (trpA trpE tnd) cultured in LB broth without selective pressure, a pBR322 derivative bearing the E. coli tryptophan Operon (pBR322-trp) was rapidly lost: after 27 cell-number doublings, only 7% cells retained both tryptophan prototrophy (Trp+) and ampicillin resistance (Apr), and 17% were Apr but Trp?. Insertion of the mini-F DNA from F factor into this plasmid effectively suppressed both the plasmid loss and the discoordinate loss of Trp+: the percentage of Trp? cells per cell-number doubling was decreased more than 100-fold. Partial derepression of the trp operon due to 3-indole acrylic acid further decreased the stability of the pBR322-trp but not that of the mini-F-inserted pBR322-trp. 相似文献
14.
Cloning of Genes Involved in the Synthesis of Pyrrolnitrin from Pseudomonas fluorescens and Role of Pyrrolnitrin Synthesis in Biological Control of Plant Disease 总被引:5,自引:2,他引:5
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D. S. Hill J. I. Stein N. R. Torkewitz A. M. Morse C. R. Howell J. P. Pachlatko J. O. Becker J. M. Ligon 《Applied microbiology》1994,60(1):78-85
A soil isolate of Pseudomonas fluorescens (BL915) was shown to be an effective antagonist of Rhizoctonia solani-induced damping-off of cotton. Investigation of the biological basis of this antagonism revealed that the strain produces pyrrolnitrin, a secondary metabolite known to inhibit R. solani and other fungi. Mutants of strain BL915 that did not produce pyrrolnitrin and did not suppress damping-off of cotton by R. solani were generated by exposure to N-methyl-N′ -nitro-N-nitrosoguanidine. A gene region that was capable of restoring pyrrolnitrin production to the non-pyrrolnitrin-producing mutants and of conferring this ability upon two other P. fluorescens strains not otherwise known to produce this compound or to be capable of suppressing damping-off caused by R. solani was isolated from strain BL915. The non-pyrrolnitrin-producing strains (mutants of BL915 and the other two P. fluorescens strains) which synthesized pyrrolnitrin after the introduction of the gene region from strain BL915 were also shown to be equal to strain BL915 in their ability to suppress R. solani-induced damping-off of cotton. These results indicate that we have isolated from P. fluorescens BL915 a gene(s) that has a role in the synthesis of pyrrolnitrin and that the production of this compound has a role in the ability of this strain to control damping-off of cotton by R. solani. 相似文献
15.
Background
Mycoplasmas are cell wall-less bacteria which encode a minimal set of proteins. In Mycoplasma hominis, the genes encoding the surface-localized membrane complex P60/P80 are in an operon with a gene encoding a cytoplasmic, nucleotide-binding protein with a characteristic Histidine triad motif (HinT). HinT is found in both procaryotes and eukaryotes and known to hydrolyze adenosine nucleotides in eukaryotes. Immuno-precipitation and BIACore analysis revealed an interaction between HinT and the P80 domain of the membrane complex. As the membrane anchored P80 carries an N-terminal uncleaved signal peptide we have proposed that the N-terminus extends into the cytoplasm and interacts with the cytosolic HinT. 相似文献16.
Antibiotic-producing Pseudomonas chlororaphis strains DF190 and PA23, Bacillus cereus strain DFE4 and Bacillus amyloliquefaciens strain DFE16 were tested for elicitation of induced systemic resistance (ISR) and direct antibiosis in control of blackleg
in canola caused by the fungal pathogen Leptosphaeria maculans. Inoculation of bacteria 24 h and 48 h prior to the pathogen was crucial for disease control. In systemic induction studies,
the bacteria and culture extracts had lower but significant suppression of the blackleg lesion. When inoculated at the same
wound site as the pathogen pycnidiospores, the bacterial culture extracts had significantly higher reduction of blackleg lesion
development. However, localized plant defense-related enzyme activity at the site of inoculation was not induced by all the
bacteria. Direct antifungal activity at the infection site seems to be the dominant mechanism mediating control of L. maculans. A Tn5-gacS mutant of strain PA23 exhibited a complete loss of antifungal and biocontrol activity, which was restored upon addition of
the gacS gene in trans. Interestingly, a phenazine-minus derivative of PA23 that produces elevated levels of pyrrolnitrin exhibited
the same or higher blackleg disease suppression compared to the wild type. These findings suggest that direct antifungal activity,
possibly mediated by pyrrolnitrin, and some low level of induced systemic resistance is involved in P. chlororaphis biocontrol of blackleg. 相似文献
17.
Ken-ichi Ishiwata Tadashi Suzuki Satoru Iwamori Setsuo Yoshino Nobuyoshi Makiguchi 《Biotechnology letters》1990,12(3):185-190
Summary The tryptophan synthase genes,trpA andtrpB, from a moderate thermophile,Bacillus
stearothermophilus IFO13737, were expressed efficiently inEscherichia
coli. The recombinant tryptophan synthase amounted to 22% of the soluble cellular protein, and was purified to homogeneity by three steps. The enzyme is more thermostable thanE.coli tryptophan synthase, especially the subunit. The enzyme is also more resistant to sodium dodecylsulfate and methanol thanE.coli enzyme. 相似文献
18.
To establish a baseline sensitivity of Botrytis cinerea to pyrrolnitrin, an antibiotic produced by several biological control agents, 204 isolates were tested for sensitivity to
pyrrolnitrin using a spore germination assay. The results showed that the isolates exhibited a wide range of sensitivity to
pyrrolnitrin, with an 8.4-fold difference in EC50 (effective concentration to reduce spore germination by 50% comparing to the control) values between the least and the most
sensitive isolates. The model-based clustering analysis indicates that the distribution of the EC50 values best fit a normal mixture model with three components and unequal variance. The less sensitive isolates were also
multidrug resistant isolates. The efficacy of the pyrrolnitrin-producing Pseudomonas chlororaphis ChPhzS24 strain was tested in vitro and on tomato plants with isolates of B. cinerea having different EC50 values. Whatever the EC50 value of the isolates tested, no significant differences in sensitivity were observed towards this bacterium indicating an
absence of resistance to this biological control agent within B. cinerea isolates and suggesting also that additional mechanisms of action are probably operated by this biological control agent. 相似文献
19.
Masato Terasawa Masayuki Inui Yasukazu Uchida Miki Kobayashi Yasurou Kurusu Hideaki Yukawa 《Applied microbiology and biotechnology》1991,34(5):623-627
Summary The application of an inducible regulation system using the trytophanase operon promoter (TPase promoter; Ptna) was examined for its high expression of the tryptophan synthase (TS) gene in Escherichia coli. The main problem in the application of Ptna for industrial purposes is catabolite repression by glucose, since glucose is the most abundant carbon source. However, this problem could be avoided by changing glucose to an organic acid, such as succinate, fumarate, malate and acetate, in the course of cultivation after glucose initially added was completely consumed. Under these conditions, l-tryptophan was also used to induce tryptophan synthase. Thus, the specific activity of TS in E. coli strain no. 168 harbouring pBR322F-PtnaTS was increased 500-fold compared to that of the cultured host strain. About 1 mol l-tryptophan/l reaction mixture was formed from indole and l-serine at 37° C for 3.5 h.
Offprint requests to: H. Yukawa 相似文献
20.
Bisphenol A (2,2-bis(4-hydroxyphenyl) propane, BPA), which is used as a synthetic resin material or a plasticizer, is a pollutant
that␣possesses endocrine-disrupting activity. Bioremediation of BPA is used to decrease its polluting effects, and here we
report a novel bacterial strain AO1, which is able to degrade BPA. This strain was isolated using enrichment cultivation from
a soil sample from a vegetable-growing field; the sample was one of 500 soil samples collected across Japan. Strain AO1 degraded
100 mg/l BPA to an undetectable level within 6 h in MYPG medium (containing malt extract, yeast extract, peptone, and glucose) and within 48 h in minimum medium containing 1% glucose at 30°C. Strain AO1 can utilize BPA as a sole source of carbon
and as an energy source under aerobic conditions. The estrogenic activity of BPA in MYPG medium was ultimately reduced by
strain AO1, although the activity initially increased. Taxonomical analysis showed that strain␣AO1 is closely related to Sphingomonas chlorophenolicum and S. herbicidovorans, neither of which have a capacity for BPA degradation. DNA–DNA hybridization showed that strain AO1 is a novel species of
the Sphingomonas genus, and we designated AO1 as S. bisphenolicum. 相似文献