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1.
Genomic analysis of a hyperthermophilic archaeon, Thermococcus sp. NA1, revealed an ORF of 1689 bases encoding 562 amino acids that showed a high similarity to DNA ligases from other hyperthermophilic archaea. The ligase, which was designated TNA1_lig (Thermococcus sp. NA1 ligase), was cloned and expressed in Escherichia coli. The recombinant TNA1_lig was purified by metal affinity chromatography. The optimum ligase activity of the recombinant TNA1_lig occurred at 80 °C and pH 7.5. The enzyme was activated by MgCl2 and ZnCl2 but was inhibited by MnCl2 and NiCl2. Additionally, the enzyme was activated by either ATP or NAD+. Revisions requested 27 October 2005; Revisions received 14 December 2005  相似文献   

2.
Comamonas strain CNB-1 was isolated from a biological reactor treating wastewater from a p-chloronitrobenzene production factory. Strain CNB-1 used p-chloronitrobenzene as sole source of carbon, nitrogen, and energy. A 2-aminophenol 1,6-dioxygenase was purified from cells of strain CNB-1. The purified 2-aminophenol 1,6-dioxygenase had a native molecular mass of 130 kDa and was composed of - and -subunits of 33 and 38 kDa, respectively. This enzyme is different from currently known 2-aminophenol 1,6-dioxygenases in that it: (a) has a higher affinity for 2-amino-5-chlorophenol (Km=0.77 M) than for 2-aminophenol (Km=0.89 M) and (b) utilized protocatechuate as a substrate. These results suggested that 2-amino-5-chlorophenol, an intermediate during p-chloronitrobenzene degradation, is the natural substrate for this enzyme. N-terminal amino acids of the - and -subunits were determined to be T-V-V-S-A-F-L-V and M-Q-G-E-I-I-A-E, respectively. A cosmid library was constructed from the total DNA of strain CNB-1 and three clones (BG-1, BG-2, and CG-13) with 2-aminophenol 1,6-dioxygenase activities were obtained. DNA sequencing of clone BG-2 revealed a 15-kb fragment that contained two ORFs, ORF9 and ORF10, with N-terminal amino acid sequences identical to those of the - and -subunits, respectively, from the purified 2-aminophenol 1,6-dioxygenase. The enzyme was actively synthesized when the genes coding for the ORF9 and ORF10 were cloned into Escherichia coli.  相似文献   

3.
Summary Rhodocyclus gelatinosus grew photosynthetically in the light and consumed H2 at a rate of about 665 nmol/min per mg protein. The uptake-hydrogenase (H2ase) was found to be membrane bound and insensitive to inhibition by CO. The structural genes of R. gelatinosus uptake-H2ase were isolated from a 40 kb cosmid gene library of R. gelatinosus DNA by hybridization with the structural genes of uptake-H2ase of Bradyrhizobium japonicum and Rhodobacter capsulatus. The R. gelatinosus genes were localized on two overlapping DNA restriction fragments subcloned into pUC18. Two open reading frames (ORF1 and ORF2) were observed. ORF1 contained 1080 nucleotides and encoded a 39.4 kDa protein. ORF2 had 1854 nucleotides and encoded a 68.5 kDa protein. Amino acid sequence analysis suggested that ORF1 and ORF2 corresponded to the small (HupS) and large (HupL) subunits, respectively, of R. gelatinosus uptake-H2ase. ORF1 was approximately 80% homologous with the small, and ORF2 was maximally 68% homologous with the large subunit of typical membrane-bound uptake-H2ases.  相似文献   

4.
A thermophilic coccoid methanogenic bacterium, strain TCI, that grew optimally around 55° C was isolated with 2-propanol as hydrogen donor for methanogenesis from CO2. H2, formate or 2-butanol were used in addition. Each secondary alcohol was oxidized to its ketone. Growth occurred in defined freshwater as well as salt (2% NaCl, w/v) medium. Acetate was required as carbon source, and 4-aminobenzoate and biotin as growth factors. A need for molybdate or alternatively tungstate was shown.Strain TCI was further characterized together with two formerly isolated mesophilic secondary alcohol-utilizing methanogens, the coccoid strain CV and the spirilloid strain SK. The guanine plus cytosine content of the DNA of the three strains was 55,47, and 39 mol%, respectively. Determination of the molecular weights of the methylreductase subunits and sequencing of ribosomal 16S RNA of strains TCI and CV revealed close relationships to the genus Methanogenium. The new isolate TCI is classified as a strain of the existing species, Methanogenium thermophilum (thermophilicum). For strain CV, that uses ethanol or 1-propanol in addition, a classification as new species, Methanogenium organophilum, is proposed. Strain SK is affiliated with the existing species, Methanospirillum hungatei. The ability to use secondary alcohols was also tested with described species of methanogens. Growth with secondary alcohols was observed with Methanogenium marisnigri, Methanospirillum hungatei strain GP1 and Methanobacterium bryantii, but not with Methanospirillum strains JF1 and M1h, Methanosarcina barkeri, Methanococcus species or thermophilic strains or species other than the new isolate TCI.  相似文献   

5.
Summary The cloning, expression and nucleotide sequence of a 3 kb DNA segment on pLS206 containing a xylanase gene (xynB) from Butyrivibrio fibrisolvens H17c was investigated. The open reading frame (ORF) of 1905 by encoded a xylanase of 635 amino acid residues (Mr 73156). At least 850 by at the 3 end of the gene could be deleted without loss of xylanase activity. The deduced amino acid sequence was confirmed by purifying the enzyme and subjecting it to N-terminal amino acid sequence analysis. In Escherichia coli C600 (pLS206) cells the xylanase was localized in the cytoplasm. Its optimum pH for activity was between pH 5.4 and 6, and optimum temperature 55° C. The primary structure of the xylanase showed a significant level of identity with a cellobiohydrolase/endoglucanase of Caldocellum saccharolyticum, as well as with the xylanases of the alkaliphilic Bacillus sp. strain C-125, B. fibrisolvens strain 49, and Pseudomonas fluorescens subsp. cellulosa.Abbreviations ORF open reading frame - pNPCase p-nitrophen-yl--d-cellobiosidase - (xynB) gene coding for XynB - XynB xylanase  相似文献   

6.
Two degenerate primers established from the consensus sequences of bacterial leucine aminopeptidases (LAP) were used to amplify a 360-bp gene fragment from the chromosomal DNA of thermophilic Bacillus kaustophilus CCRC 11223 and the amplified fragment was successfully used as a probe to clone a leucine aminopeptidase (lap) gene from a genomic library of the strain. The gene consists of an open reading frame (ORF) of 1,494 bp and encodes a protein of 497 amino acid residues with a calculated molecular mass of 53.7 kDa. The complete amino acid sequence of the cloned enzyme showed greater than 30% identity with prokaryotic and eukaryotic LAPs. Phylogenetic analysis showed that B. kaustophilus LAP is closely related to the enzyme from Bacillus subtilis and is grouped with the M17 family. His6-tagged LAP was generated in Escherichia coli by cloning the coding region into pQE-30 and the recombinant enzyme was purified by nickel-chelate chromatography. The pH and temperature optima for the purified enzyme were 8 and 65°C, respectively, and 50% of its activity remained after incubation at 60°C for 32 min. The enzyme preferentially hydrolyzed l-leucine-p-nitroanilide (l-Leu-p-NA) followed by Cys derivative.Communicated by G. Antranikian  相似文献   

7.
Cytochromes b, c, d, and o were identified by spectroscopic analysis of respiratory membrane fragments from Vitreoscilla sp., strain C1. Carbon monoxide difference spectra of the reduced membranes had absorption maxima at 416, 534, and 571 nm (ascribed to cytochrome o) and 632 nm (cytochrome d). Derivative spectra of the pyridine hemochromogen spectra of the membranes identified the presence of b- and c-type cytochromes in Vitreoscilla. The cyanide binding curve of the membranes was biphasic with dissociation constants of 2.14 mM and 10.7 mM which were assigned to cytochrome o and cytochrome d, respectively. Membranes bound carbon monoxide with dissociation constant 3.9 M, which was assigned to cytochrome o. Cytochrome c 556 and a NADH-p-iodonitrotetrazolium violet reductase component were partially purified from Vitreoscilla membranes.Abbreviations INT p-iodonitrotetrazolium violet - RMF respiratory membrane fragments - K d dissociation constant - CHAPS 3-[(3-cholamido propyl) dimethylammonio]-1-propanesulfonate - DOC sodium deoxycholate - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecyl sulfate  相似文献   

8.
Saccharomyces sp. SK0704 (further defined as SK0704) isolated from long-term-ripening kimchi was identified by a biochemical method with an API kit; its physiology was found to be very similar to that of S. cerevisiae ATCC 26603 (further defined as ATCC 26603), except in terms of starch utilization. SK0704 did not excrete extracellular glucoamylase, but utilized starch as a sole carbon source under only aerobic conditions. Crude enzyme excreted from SK0704 catalyzed the saccharification of starch to glucose, but ATCC 26603 did not. The PCR product obtained using the chromosomal DNA of SK0704 and the primers designed on the basis of the extracellular glucoamylase-coding gene of S. diastaticus was homologous with the intracellular sporulation-specific glucoamylase of S. cerevisiae. SDS-PAGE pattern of soluble protein extracted from yeast cells grown on glucose was greatly different from that on starch. From these results, we proposed that the SK0704 may have a specific physiological function for starch catabolism such as membrane transport system and intracellular sac-charification of starch.  相似文献   

9.
Heterofermentative, lactic acid-producing, gram-positive, motile bacteria were isolated from the waters of Ace Lake, Antarctica. All strains produced virtually only l(+)lactic acid from d(+)glucose. d(–)ribose was fermented to lactic, acetic, and formic acids, and ethanol. Cell walls contained meso-diaminopimaleic acid. The strains did not grow at 30°C and were psychrotrophic. Whole cells contained 18:1cis 9 as a major component of their fatty acids. At 20°C, the strains grew better anaerobically than aerobically and all strains lacked catalase, oxidase and respiratory lipoquinones. DNA that coded for most of the 16S rRNA gene of one of the strains was amplified by the polymerase chain reaction and sequenced. The strain was phylogenetically most closely related to Carnobacterium mobile (Knuc=0.0214). The isolates separated into two phenotypes. DNA/DNA homology studies determined on a representative from each phenotype showed low homology between the phenotypes (38±8%), and with Carnobacterium mobile (26±2%, 34±2%). Carnobacterium funditum sp. nov. produced acid from mannitol, trehalose, but not amygdalin. The G+C content of the DNA was 32–34%, and the Type strain is DSM 5970 (=ACAM 312). Carnobacterium alterfunditum sp. nov. produced acid weakly from amygdalin but not from mannitol or trehalose. The G+C content was 33–34%, and the Type strain is DSM 5972 (=ACAM 313).  相似文献   

10.
The actI gene, encoding a component of the actinorhodin polyketide synthase of Streptomyces coelicolor, was used to identify and clone a homologous 11.7 kb BamHI DNA fragment from Saccharopolyspora hirsuta 367. The cloned fragment complemented actinorhodin production in a strain of Streptomyces coelicolor bearing a mutant actI gene. The DNA sequence of a 5.1 kb fragment revealed 6 open reading frames (ORF). ORF1 does not resemble any known DNA or deduced protein sequence, while the deduced protein sequence of ORF2 resembles that of biotin carboxyl carrier proteins. Based on the similarity to deduced protein sequences from cloned genes of polyketide producers, ORF3 would code for a ketoreductase, ORF4 and ORF5 for the putative heterodimeric -ketoacyl synthase, and ORF6 for an acyl carrier protein.  相似文献   

11.
A short (43-bp) A/T-rich stretch of DNA located in The intergenic region between thebaiA2 andbaiF genes fromEubacterium sp. strain VPI 12708 was amplified by polymerase chain reaction (PCR) and inserted in front of the Shine-Dalgarno (SD) sequences of three inefficiently-expressedEubacterium sp. strain VPI 12708 genes cloned inEschcrichia coli plasmids. Insertion of this A/T-rich cassette increased gene expression in all cases tested. Deletion of part of the A/T-rich region from abaiF clone in pUC19 resulted in decreased gene expression. Synthesis of specific mRNA was increased with addition of the A/T-rich cassette to constructs containing thebaiC gene from Eubacterium sp. strain VPI 12708, but mRNA synthesis was not significantly changed in cells containing plasmid constructs with thebaiF andbaiG genes. Enhanced translation resulting from a decrease in mRNA secondary structure in the ribosome binding site region is discussed as a possible reason for increased gene expression with the A/T-rich cassette.  相似文献   

12.
Oily sludge degradation by bacteria from Ankleshwar, India   总被引:7,自引:0,他引:7  
Three bacterial strains, Bacillus sp. SV9, Acinetobacter sp. SV4 and Pseudomonas sp., SV17 from contaminated soil in Ankleshwar, India were tested for their ability to degrade the complex mixture of petroleum hydrocarbons (such as alkanes, aromatics, resins and asphaltenes), sediments, heavy metals and water known as oily sludge. Gravimetric analysis showed that Bacillus sp. SV9 degraded approx. 59% of the oily sludge in 5 days at 30 °C whereas Acinetobacter sp. SV4 and Pseudomonas sp. SV17 degraded 37% and 35%. Capillary gas chromatographic analysis revealed that after 5 days the Bacillus strain was able to degrade oily sludge components of chain length C12–C30 and aromatics more effectively than the other two strains. Maximum drop in surface tension (from 70 to 28.4 mN/m) was accompanied by maximum biosurfactant production (6.7 g l−1) in Bacillus sp. SV9 after 72 h, these results collectively indicating that this bacterial strain has considerable potential for bioremediation of oily sludge.  相似文献   

13.
Formyltetrahydrofolate synthetase (FTHFS) (EC 6.3.4.3), a thermostable protein of four identical subunits from Clostridium thermoaceticum was cloned into Escherichia coli SK1592. The clone (CRL47) contained a 9.5 kb EcoRI fragment of C. thermoaceticum DNA ligated into pBR322. It produced catalytically active, thermostable FTHFS, that was not found in E. coli SK1592 containing native pBR322. The identity of the expressed enzyme was confirmed by specific binding of rabbit polyclonal anti-FTHFS serum produced against C. thermoaceticum FTHFS. The specific activities (mol·min-1·mg-1) of FTHFS in cell free extracts of CRL47 were 28–89 when assayed at 50°C and pH8. This was from 3–10-fold higher than in C. thermoaceticum extracts. FTHFS was purified to homogeneity from CRL47. The purified enzyme behaved during electrophoresis and gel chromatography and it had similar specific activity and thermostability as the enzyme purified from C. thermoaceticum.Abbreviations FTHFS formyltetrahydrofolate synthetase - kb kilobase - H4-folate tetrahydrofolate - SDS sodium dodecyl sulfate A preliminary account of this work was presented at the annual meeting of the American Society for Microbiology, Atlanta, GA, 1987 (C. R. Lovell, A. Przybyla and L. G. Ljungdahl, Abstr. Annu. Meet. Am. Soc. Microbiol. 1987, K126, p. 223).  相似文献   

14.
SIRE-1 is a family of several hundred dispersed copies of a very large DNA element from Glycine max that has features characteristic of retroviruses and retrotransposons. A 2.4 kb SIRE-1-specific fragment was recovered from a soybean cDNA library and sequenced. The sequence contains two ORFs. Theoretical translation of ORF1 produces a gag-prot-like polyprotein containing highly conserved motifs found in retroelement nucleocapsids (CX2CX4HX4C) and aspartic proteases (LDSG). The second ORF is foreshortened. The cDNA also contains nearly 200 bp of a putative 5 LTR just upstream of a tRNA primer-binding site.  相似文献   

15.
l-myo-inositol 1-phosphate synthase (EC 5.5.1.4; MIPS) catalyzes the first rate limiting conversion of d-glucose 6-phosphate to l-myo-inositol 1-phosphate in the inositol biosynthetic pathway. In an earlier communication we have reported two forms of MIPS in Synechocystis sp. PCC6803 (Chatterjee et al. in Planta 218:989–998, 2004). One of the forms with a ~50 kDa subunit has been found to be coded by an as yet unassigned ORF, sll1722. In the present study we have purified the second isoform of MIPS as a ~65 kDa protein from the crude extract of Synechocystis sp. PCC6803 to apparent homogeneity and biochemically characterized. MALDI-TOF analysis of the 65 kDa protein led to its identification as acetolactate synthase large subunit (EC 2.2.1.6; ALS), the putatively assigned ORF sll1981 of Synechocystis sp. PCC6803. The PCR amplified ~1.6 kb product of sll1981 was found to functionally complement the yeast inositol auxotroph, FY250 and could be expressed as an immunoreactive ~65 kDa MIPS protein in the natural inositol auxotroph, Schizosaccharomyces pombe. In vitro MIPS activity and cross reactivity against MIPS antibody of purified recombinant sll1981 further consolidated its identity as the second probable MIPS gene in Synechocystis sp. PCC6803. Sequence comparison along with available crystal structure analysis of the yeast MIPS reveals conservation of several amino acids in sll1981 essential for substrate and co-factor binding. Comparison with other prokaryotic and eukaryotic MIPS sequences and phylogenetic analysis, however, revealed that like sll1722, sll1981 is quite divergent from others. It is probable that sll1981 may code for a bifunctional enzyme protein having conserved domains for both MIPS and acetolactate synthase (ALS) activities.Anirban Chatterjee and Krishnarup Ghosh Dastidar contributed equally.  相似文献   

16.
An endopolygalacturonase of Rhizopus sp. strain LKN, one of several isolates from tempe starter (ragi), was purified 235-fold by CM-Sephadex C-50, DEAE-Sephadex A-50 ion exchange chromatographies and Sephadex G-75 gel filtration. The purified enzyme was homogeneous by SDS-PAGE with a M r of 38.5 kDa. Its K m value for pectic acid was 2 mg/ml. It was stable at pH 4.5 to 11 and up to 50°C, with optimum activity at pH 4.5 to 4.75 and 55 to 60°C. Some ionic compounds enhanced the enzyme activity, whereas tannic acid at 0.5 mm caused about 90% inhibition.The authors are with the Department of Food Science and Technology, Faculty of Agriculture, Kyushu University, Hakozaki, Fukuoka 812, Japan.  相似文献   

17.
A bacterial strain WJ-98 found to produce active extracellular keratinase was isolated from the soil of a poultry factory. It was identified asParacoccus sp. based on its 16S rRNA sequence analysis, morphological and physiological characteristics. The optimal culture conditions for the production of keratinase byParacoccus sp. WJ-98 were investigated. The optimal medium composition for keratinase production was determined to be 1.0% keratin, 0.05% urea and NaCl, 0.03% K2HPO4, 0.04% KH2PO4, and 0.01% MgCl2·6H2O. Optimal initial pH and temperature for the production of keratinase were 7.5 and 37°C, respectively. The maximum keratinase production of 90 U/mL was reached after 84 h of cultivation under the optimal culturing conditions. The keratinase fromParacoccus sp. WJ-98 was partially purified from a culture broth by using ammonium sulfate precipitation, ion-exchange chromatography on DEAE-cellulose, followed by gel filtration chromatography on Sephadex G-75. Optimum pH and temperature for the enzyme reaction were pH 6.8 and 50°C, respectively and the enzymes were stable in the pH range from 6.0 to 8.0 and below 50°C. The enzyme activity was significantly inhibited by EDTA, Zn2+ and Hg2+. Inquiry into the characteristics of keratinase production from these bacteria may yield useful agricultural feed processing applications.  相似文献   

18.
Vibrio sp. GMD509, a marine bacterium isolated from eggs of the sea hare, exhibited lipolytic activity on tributyrin (TBN) plate, and the gene representing lipolytic activity was cloned. As a result, an open reading frame (ORF) consisting of 1,017 bp (338 aa) was found, and the deduced amino acid sequence of the ORF showed low similarity (<20%) to α/β hydrolases such as dienelactone hydrolases and esterase/lipase with G–X1–S–X2–G sequence conserved. Phylogenetic analysis suggested that the protein belonged to a new family of esterase/lipase together with various hypothetical proteins. The enzyme was overexpressed in Escherichia coli and purified to homogeneity. The purified enzyme (Vlip509) showed the best hydrolyzing activity toward p-nitrophenyl butyrate (C4) among various p-nitrophenyl esters (C2 to C18), and optimal activity of Vlip509 occurred at 30°C and pH 8.5, respectively. Kinetic parameters toward p-nitrophenyl butyrate were determined as K m (307 μM), k cat (5.72 s−1), and k cat/K m (18.61 s−1 mM−1). Furthermore, Vlip509 preferentially hydrolyzed the S-enantiomer of racemic ofloxacin ester. Despite its sequence homology to dienelactone hydrolase, Vlip509 showed no dienelactone hydrolase activity. This study represents the identification of a novel lipolytic enzyme from marine environment.  相似文献   

19.
A new deoC gene encoding deoxyribose 5-phosphate aldolase (DERA) was identified in Yersinia sp. EA015 isolated from soil. The DERA gene had an open reading frame (ORF) of 672 base pairs encoding 223 amino acids to yield a protein of molecular mass 24.8 kDa. The amino acid sequence was 94% identical to that of DERA from Yersinia intermedia ATCC 29909. DERA was over-expressed in Escherichia coli and purified using Ni–NTA affinity chromatography. The specific activity was 137 μmol/min/mg. The Michaelis constant (km value) of DERA was 9.1 mM. DERA was optimally active at pH 6.0 and 50 °C. DERA was tolerant to a high concentration (300 mM) of acetaldehyde.  相似文献   

20.
Chromobacterium sp. strain DS-1 produces an extracellular cholesterol oxidase that is very stable at high temperatures and in the presence of organic solvents and detergents. In this study, we cloned and sequenced the structural gene encoding the cholesterol oxidase. The primary translation product was predicted to be 584 amino acid residues. The mature product is composed of 540 amino acid residues. The amino acid sequence of the product showed significant similarity (53–62%) to the cholesterol oxidases from Burkholderia spp. and Pseudomonas aeruginosa. The DNA fragment corresponding to the mature enzyme was subcloned in the pET-21d(+) expression vector and expressed as an active product in Escherichia coli. The cholesterol oxidase produced from the recombinant E. coli was purified to homogeneity. The physicochemical properties were similar to those of native enzyme purified from strain DS-1. K m and V max values of the cholesterol oxidase were estimated from Lineweaver–Burk plots. The V max/K m ratio of the enzyme was higher than those of commercially available cholesterol oxidases. The circular dichroism spectral analysis of the recombinant DS-1 enzyme and Burkholderia cepacia ST-200 cholesterol oxidase showed that the conformational stability of the DS-1 enzyme was higher than that of B. cepacia ST-200 enzyme at higher temperatures.  相似文献   

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