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991.
Combination of the tod and the tol pathways in redesigning a metabolic route of Pseudomonas putida for the mineralization of a benzene, toluene, and p-xylene mixture.
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Construction of a hybrid strain which is capable of mineralizing components of a benzene, toluene, and p-xylene mixture simultaneously was attempted by redesigning the metabolic pathway of Pseudomonas putida. Genetic and biochemical analyses of the tod and the tol pathways revealed that dihydrodiols formed from benzene, toluene, and p-xylene by toluene dioxygenase in the tod pathway could be channeled into the tol pathway by the action of cis-p-toluate-dihydrodiol dehydrogenase, leading to complete mineralization of a benzene, toluene, and p-xylene mixture. Consequently, a hybrid strain was constructed by cloning todC1C2BA genes encoding toluene dioxygenase on RSF1010 and introducing the resulting plasmid into P. putida mt-2. The hybrid strain of P. putida TB105 was found to mineralize a benzene, toluene, and p-xylene mixture without accumulation of any metabolic intermediate. 相似文献
992.
Two cloning vectors designed for use in Escherichia coli and the thiobacilli were constructed by combining a Thiobacillus intermedius plasmid replicon with a multicloning site, lacZ(prm1), and either a kanamycin or a streptomycin resistance gene. Conditions necessary for the introduction of DNA into T. intermedius and T. neapolitanus via electroporation were examined and optimized. By using optimal electroporation conditions, the gene encoding a carboxysome shell protein, csoS1A, was insertionally inactivated in T. neapolitanus. The mutant showed a reduced number of carboxysomes and an increased level of CO(inf2) necessary for growth. 相似文献
993.
Anaerobic degradation of halogenated phenols by sulfate-reducing consortia. 总被引:4,自引:2,他引:2
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Sulfidogenic consortia enriched from an estuarine sediment were maintained on either 2-, 3-, or 4-chlorophenol as the only source of carbon and energy for over 5 years. The enrichment culture on 4-chlorophenol was the most active and this consortium was selected for further characterization. Utilization of chlorophenol resulted in sulfate depletion corresponding to the values expected for complete mineralization to CO2. Degradation of 4-chlorophenol was coupled to sulfate reduction, since substrate utilization was dependent on sulfidogenesis and chlorophenol loss did not proceed in the absence of sulfate. Other sulfur oxyanions, sulfite or thiosulfate, also served as electron acceptors for chlorophenol utilization, while carbonate, nitrate, and fumarate did not. The sulfidogenic consortium utilized phenol, 4-bromophenol, and 4-iodophenol in addition to 4-chlorophenol. 4-Fluorophenol, however, did not serve as a substrate. 4-Bromo- and 4-iodophenol were degraded with stoichiometric release of halide, and 4-[14C]bromophenol was mineralized, with 90% of the radiolabel recovered as CO2. 相似文献
994.
Characterization of the endosymbiont of a deep-sea bivalve, Calyptogena soyoae. 总被引:1,自引:0,他引:1
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We have purified DNA from gill tissue of a marine bivalve, Calyptogena soyoae, collected from the deep-sea cold seep communities in Sagami Bay, Japan. An rRNA gene was amplified, cloned, and sequenced. In situ hybridization revealed that the sequence is that of a bacterial endosymbiont within the gill of C. soyoae. 相似文献
995.
996.
高必需氨基酸转基因马铃薯的研究 总被引:8,自引:0,他引:8
80年代以来,马铃薯遗传转化系统日趋成熟,转基因工程植株已被广泛应用于基础科学研究[1]。作为食物蛋白和能量主要来源的马铃薯,提高其蛋白质含量及质量的遗传工程研究正受到人们的普遍关注[2]。Yang等[2]将旨在改善氨基酸平衡的CAT-HEAAE(氯酶素乙酰转移酶-高含量人体必需氨基酸)融合基因导入马铃薯,获得了Southernblot、Northernblot、Westernblot的证据,但尚缺少氨基酸分析的资料。玉米醇溶蛋白(zein)[3]是一个富含甲硫氨酸的贮存蛋白,它和人工合成的HE… 相似文献
997.
编码天麻抗真菌蛋白cDNA的分子克隆 总被引:9,自引:0,他引:9
用重组DNA 技术研究了编码天麻抗真菌蛋白(GAFP)的基因,从天麻(Gastrodia elataBl.)块茎中提取Poly(A) m RNA 后合成cDNA,构建成表达型cDNA 文库,用纯化的蛋白质探针通过免疫筛选找出对应的cDNA 克隆。在进一步证明所选用的cDNA 克隆含有重组的λ-phage DNA 后,提取和纯化含有插入片段重组子的DNA,用Eco RI酶切分析可见插入片段。已分离出编码天麻抗真菌蛋白的基因 相似文献
998.
Callus cultures and cell suspension cultures derived from Ginkgo biloba L. leaves produced ginkgolidc B. In cell suspension cultures, the production reached a maximum by the 13th day of subculture and followed by a sharp decrease. The medium of Murashige and Skoog induced the highest ginkgolide B content in cultures while the medium of Schenk and Hildebrandt promoted cell growth. For the maximal production of ginkgolide B, cells were cultured in Murashige and Skoog medium modified to contain 1.0 mg/l of -naphthaleneacetic acid, 0.1 mg/1 of kinetin, 30 g/1 sucrose and 1.25 mM potassium phosphate with a molar ratio of ammonium to nitrate ions of 1 3.Abbreviations B5
Gamborg et al (1968) medium
- GKB
Ginkgolide B
- MS
Murashige and Skoog (1962) medium
- NAA
-naphthaleneacetic aicd
- SH
Schenk and Hildebrandt (1972) medium 相似文献
999.
Mutational analysis of the att DNA-binding domain of phage Mu transposase. 总被引:2,自引:1,他引:1
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The transposase (A protein) of phage Mu encodes binding to two families of DNA sites, att sites located at the Mu ends and enhancer sites located internally. Separate subdomains in the N-terminal domain I of Mu A protein are known to be involved in recognition of the att and enhancer sites. We have delineated an approximately 135 aa region within domain I beta gamma that specifies binding to Mu att sites. This peptide was overexpressed and its properties compared with that of the larger domain I beta gamma as well as the intact Mu A protein. Extensive mutagenesis of residues around a putative helix-turn-helix DNA-binding motif within the I beta domain identified several mutants defective in DNA transposition in vivo. Of these, Mu A(K157Q) was completely defective in att DNA-binding. Mu A(F131S) and Mu A(R146N) had a lower affinity for att DNA and low levels of transposition in vitro. Our results indicate that residues in the gamma region are required for activity and that residues outside the beta gamma region must also influence discrimination between the multiple att sites. 相似文献
1000.
To localize the DNA binding domain of the Saccharomyces cerevisiae Ars binding factor 1 (ABF1), a multifunctional DNA binding protein, plasmid constructs carrying point mutations and internal deletions in the ABF1 gene were generated and expressed in Escherichia coli. Normal and mutant ABF1 proteins were purified by affinity chromatography and their DNA binding activities were analyzed. The substitution of His61, Cys66 and His67 respectively, located in the zinc finger motif in the N-terminal region (amino acids 40-91), eliminated the DNA binding activity of ABF1 protein. Point mutations in the middle region of ABF1, specifically at Leu353, Leu399, Tyr403, Gly404, Phe410 and Lys434, also eliminated or reduced DNA binding activity. However, the DNA binding activity of point mutants of Ser307, Ser496 and Glu649 was the same as that of wild-type ABF1 protein and deletion mutants of amino acids 200-265, between the zinc finger region and the middle region (residues 323-496) retained DNA binding activity. As a result, we confirmed that the DNA binding domain of ABF1 appears to be bipartite and another DNA binding motif, other than the zinc finger motif, is situated between amino acid residues 323 and 496. 相似文献