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T Beppu

Publications and source records attributed to T Beppu.

At least 163 records · Page 9Linked to original sources
PubMed1993

Production of poly(L-aspartyl-L-phenylalanine) in Escherichia coli.

The dipeptide, Asp-Phe, is the mother compound of a sweetener, aspartame (L-aspartyl-L-phenylalanine methyl ester). Two 12-mer partially complementary nucleotides that are designed, if expressed correctly, to code for Asp-Phe-Asp-Phe were synthesized to yield long and double-stranded DNA by annealing and ligation. After addition of two stop codons to the polymeric DNA, the DNA segment was inserted between the Escherichia coli trp promoter and a transcriptional terminator derived from phage fd, resulting in plasmid pDF60 that would express a protein, (1Met-10Ile)-(Asp-Phe)61. Another plasmid, pCD111, that would express a fused protein with a constitution of the NH2-terminal 167 amino acids mostly from prochymosin and the following (Asp-Phe)61, was also constructed. The polymeric DNA on pDF60 was very unstable in most of E. coli recA strains, except for strain JM109. Upon induction of the trp promoter with beta-indoleacrylic acid, E. coli JM109 harboring pDF60 formed inclusion bodies which were observed under an optical microscope. However, analyses of the inclusion bodies revealed that they consisted of many species of proteins derived from the host strain with a small amount of the poly(Asp-Phe), which could be detected by an immunological method with anti-poly(Asp-Phe) antibody. On the other hand, pCD111 directed the synthesis of the fused poly(Asp-Phe) as inclusion bodies, which was calculated to be 11.2% of the total cellular proteins.

Amino Acid Sequence↗
PubMed1993

Characterization of secretory intermediates of Serratia marcescens serine protease produced during its extracellular secretion from Escherichia coli cells.

The Serratia marcescens serine protease (SSP; 66 kDa) is synthesized as a precursor (preproSSP; 112 kDa) composed of the NH2-terminal signal peptide of 27 amino acids, the mature protease part and a large COOH-terminal domain. When the SSP gene is expressed in Escherichia coli under the control of the tac promoter, the mature enzyme is excreted into the medium through the outer membrane, whereas preproSSP and two proteins, C-1 (40 kDa) and C-2 (38 kDa), processed from the COOH-terminal domain, are accumulated in the membrane fraction. Although treatment of the intact cells with trypsin caused slight truncation of C-1 and C-2, the main parts of C-1 and C-2, both of which are detected in the outer membrane, were resistant to trypsin, even after the cells had been osmotically shocked. Consistent with this, a high content of beta-sheet structure in C-2 was suggested by marked heat-modifiability, as determined by their electrophoretic mobilities on SDS-polyacrylamide gel. These findings suggest rigid integration of C-1 and C-2 in the outer membrane. Upon induction of the tac promoter, rapid excretion of SSP into the medium was first accompanied by the accumulation of C-1 in the outer membrane, which was followed by conversion of C-1 to C-2. PreproSSP was not detected during the accumulation of SSP in the medium, but it was gradually accumulated after the accumulation of SSP had reached a plateau. In addition, preproSSP still containing the intact NH2-terminal signal peptide was completely digested with trypsin when added to osmotically shocked cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Identification of two amino acids contributing the high enzyme activity in the alkaline pH range of an alkaline endoglucanase from a Bacillus sp.

An alkaline cellulase (beta-1,4-endoglucanase; NK1) from an alkalophilic Bacillus sp. shows great similarity in amino acid sequence to a neutral cellulase (BSC) from Bacillus subtilis, despite a considerable difference in their pH activity profiles. Multiple amino acid exchanges by site-directed mutagenesis, using BSC as the reference, were performed on the residues in region 5 of NK1, which was previously shown to be responsible for the high enzyme activity of this alkaline cellulase in a broad alkaline pH range. Two amino acid residues, Ser287 and Ala296, were identified as being responsible for the activity in the alkaline range. The double mutation, Ser287 to Asn and Ala296 to Ser, of NK1 made its pH activity profile almost the same as that of BSC. On the other hand, the pH activity profile in the acidic range was not significantly affected by various amino acid replacements including these two positions in region 5. This observation, together with the information available on other endoglucanases, suggests that the above two amino acid substitutions caused a profound effect through rearrangement of the hydrogen bond network forming the substrate-binding site or the catalytic site.

Alkalies↗
PubMed1993

Putrescine oxidase of Micrococcus rubens: primary structure and Escherichia coli.

The flavin adenine dinucleotide (FAD)-containing putrescine oxidase of Micrococcus rubens catalyses the oxidative deamination of putrescine. The amino acid sequences of the NH2-termini of the mature enzyme and lysyl-endopeptidase-generated fragments were determined for preparation of synthetic oligonucleotides as hybridization probes for cloning. A 4.4 kb BamHI fragment which contained DNA sequences hybridizing to the probes was cloned in pUC19 in Escherichia coli. The nucleotide sequence together with the determined amino acid sequences revealed that this enzyme consists of 480 amino acids (M(r) 52,000) and contains an FAD-binding consensus sequence at its NH2-terminal portion. In front of the transcriptional start point, which is 28 bases upstream of the initiation codon as determined by primer extension, -35 and -10 sequences similar to typical prokaryotic promoter consensus sequences are present. E. coli JM109 containing the putrescine oxidase gene just downstream of the lac promoter in pUC18 produced a large amount of this protein when grown at 37 degrees C but in the enzymically inactive form of inclusion bodies. However, cultivation of the recombinant E. coli cells at temperatures below 30 degrees C led to production of active enzyme (20 times as much as produced by the original M. rubens strain).

Amino Acid Sequence↗
PubMed1993

Cloning and characterization of a nitrite reductase gene from Alcaligenes faecalis and its expression in Escherichia coli.

The gene (nir) encoding the copper-containing nitrite reductase (NIR) of a denitrifying bacterium, Alcaligenes faecalis S-6, was cloned by a synthetic oligonucleotide-probing method. The nucleotide sequence of the cloned DNA fragment revealed the primary structure of the NIR precursor containing the N-terminal signal sequence for secretion. A nucleotide sequence, possibly recognized by a transcriptional regulator resembling FNR was found upstream of the structural gene. When the cloned gene was expressed in Escherichia coli under the control of the lac promoter at 37 degrees C, NIR was produced as large inclusion bodies and little activity was detected. When cultivation was at 20 degrees C, most of the NIR was detected in the soluble fraction and a significant portion of the protein was translocated into the periplasmic space, accompanied by removal of its signal sequence.

Alcaligenes↗
PubMed1993

Characterization of a cytochrome a1 that functions as a ubiquinol oxidase in Acetobacter aceti.

The terminal oxidase for ethanol oxidation in Acetobacter aceti was purified as a complex consisting of four subunits (subunits I, II, III, and IV) with molecular masses of 72, 34, 21, and 13 kDa, respectively. Spectrophotometric analysis and catalytic properties determined with the purified enzyme showed that it belonged to a family of cytochrome a1 (ba)-type ubiquinol oxidases. A polymerase chain reaction with two oligonucleotides designed for amino acid sequences that are conserved in subunit I of the aa3-type cytochrome c oxidases from various origins and of an Escherichia coli o (bo)-type ubiquinol oxidase was used for cloning the cytochrome a1 gene. A 0.5-kb fragment thus amplified was used as the probe to clone a 4.5-kb KpnI fragment that contained a putative open reading frame for the whole subunit I gene. The molecular weight and amino acid composition of the product of this open reading frame (cyaA) were the same as those of the purified protein from A. aceti. The amino acid sequence of CyaA was homologous to that of subunit I of the E. coli o-type ubiquinol oxidase. Nucleotide sequence analysis of the region neighboring the cyaA gene revealed that the genes (cyaB, cyaC, and cyaD) encoding the other three subunits (subunits II, III, and IV) were clustered upstream and downstream of the cyaA gene in the order cyaB, cyaA, cyaC, and cyaD and with the same transcription polarity, forming an operon. As expected from the enzymatic properties, CyaB, CyaC, and CyaD showed great similarity in amino acid sequence to the corresponding sununits of the E. coli o-type ubiquinol oxidase and as(3)-type cytochrome c oxidases.

Acetobacter↗
PubMed1993

Induction by ethanol of alcohol dehydrogenase activity in Acetobacter pasteurianus.

The membrane-bound alcohol dehydrogenase (ADH) activity of Acetobacter pasteurianus NCI1380 was enhanced more than 10-fold by the addition of ethanol to the medium. In order to elucidate the mechanism of the ethanol induction, a gene cluster encoding the dehydrogenase and cytochrome c subunits of ADH was cloned from this strain, and its nucleotide sequence was determined. Comparison of the deduced amino acid sequences and the NH2-terminal sequences determined with purified proteins showed that the dehydrogenase and cytochrome c subunits contained typical signal peptides of 35 and 26 amino acids, respectively. Transcriptional analysis of the cloned genes by primer extension revealed that the gene cluster was transcribed from two different promoters upstream from the dehydrogenase gene. One (59 bp upstream of the ATG start codon) of the two promoters was used in the presence of ethanol, whereas the other (232 bp upstream of the ATG start codon) was used in the absence of ethanol. Immunoblot analyses showed that almost the same amounts of the cytochrome c and the 15-kDa subunits were produced in both the presence and absence of ethanol and that the amount of the dehydrogenase subunit localized in the membrane was decreased in the absence of ethanol. This incorrect localization of the dehydrogenase subunit might be one of the factors responsible for the low ADH activity in the absence of ethanol.

Acetobacter↗
PubMed1993

A gene cluster involved in aerial mycelium formation in Streptomyces griseus encodes proteins similar to the response regulators of two-component regulatory systems and membrane translocators.

Mutants of Streptomyces griseus deficient in A-factor production are sporulation negative, since A-factor is an essential hormonal regulator for the induction of morphological and physiological differentiation in this bacterium. A DNA fragment which induced aerial mycelium formation and sporulation in an A-factor-deficient mutant strain, S. griseus HH1, was cloned from this mutant strain. Subcloning experiments and nucleotide sequencing showed that two open reading frames, ORF1 with 656 amino acids and ORF2 with 201 amino acids, were required in order to induce sporulation. The amino acid sequence of ORF1 significantly resembled that of the Escherichia coli HlyB protein, a member of a family of bacterial membrane proteins engaged in ATP-dependent secretion mechanisms. Conserved features of this surface translocator family, such as the transmembrane structure predicted by their hydropathy profiles and the amino acid sequence forming an ATP-binding fold, were also conserved in ORF1. The ORF1 gene appeared to constitute a transcriptional unit with an additional upstream gene encoding ORF3, which was greatly similar to ORF1 in size and amino acid sequence. The other protein, ORF2, showed significant end-to-end homology with the E. coli uhpA product, a regulatory protein for the uptake of sugar phosphates. Like UhpA as a response regulator of a bacterial two-component regulatory system, ORF2 contained a helix-turn-helix DNA-binding domain at its COOH-terminal portion and an Asp residue (Asp-54) probably to be phosphorylated at its NH2-terminal portion. An amino acid replacement from Asp-54 to Asn resulted in the loss of the ability of ORF2 to induce sporulation in strain HH1.

4-Butyrolactone↗
PubMed1993

Detection of an A-factor-responsive protein that binds to the upstream activation sequence of strR, a regulatory gene for streptomycin biosynthesis in Streptomyces griseus.

DNA-binding assays using mobility shift polyacrylamide gel electrophoresis revealed the presence of a protein that specifically bound to a restriction fragment -288 to -191 bp upstream from the transcriptional start point of strR, a regulatory gene for streptomycin biosynthesis in Streptomyces griseus. The binding site corresponded to an upstream activation sequence predicted from the results of in vivo promoter assays. The binding was greatly enhanced by 5 mM Mg2+. This binding was detected with the protein source only from the wild-type strain and not from an A-factor-deficient mutant strain. The exogenous supplementation of A-factor to the A-factor-deficient mutant strain caused the appearance of the protein in the DNA-binding assay. A synthetic nucleotide 52 bp in length (region from -293 to -242), which was synthesized on the basis of data obtained from both retardation assays with dissected DNA fragments and in vivo promoter assays, was retarded by the A-factor-dependent protein. In addition to this A-factor-dependent protein, at least three proteins with different recognition site affinities capable of binding to the upstream region of the strR promoter were detected. The binding of one of these proteins to both sides of the upstream activation sequence bound by the A-factor-dependent protein was completely abolished in the presence of ATP and Mg2+ in the incubation mixture. The region bound by these proteins showed anomalous electrophoretic mobility, like that of a bent DNA molecule, which is probably caused by the presence of many blocks consisting of A and T. The region bound by these proteins was found to be transcribed in the orientation opposite to that of strR.

4-Butyrolactone↗
PubMed1993

Characterization of nitrile hydratase genes cloned by DNA screening from Rhodococcus erythropolis.

Southern hybridization analysis using the genes encoding the alpha- and beta-subunits of nitrile hydratase (NHase) from Rhodococcus sp. N-774 as probe suggested that two R. erythropolis strains, JCM6823 and JCM2892, among 31 strains mainly from Japan Culture of Microorganisms (JCM) have NHase genes. Restriction analysis of DNA fragments showing positive hybridization showed that each fragment carried a nucleotide sequence very similar to that of the NHase genes from Rhodococcus sp. N-774. Nucleotide sequence analysis of the DNA fragment cloned from R. erythropolis JCM6823 showed the presence of the genes encoding the alpha- and beta-subunits of NHase, which show 94.7% and 96.2% identity in amino acid sequence to those of Rhodococcus sp. N-774, respectively, as well as a C-terminal portion of the amidase gene upstream from these genes. Despite the extremely high amino acid sequence similarity in both NHases and amidases from R. erythropolis JCM6823 and Rhodococcus sp. N-774, the NHases and amidases from R. erythropolis strains showed broader substrate specificity when compared to those from Rhodococcus sp. N-774. This suggests that a very limited number of amino acid residues are responsible for the difference in substrate specificity. Although the NHase of Rhodococcus sp. N-774 are constitutively produced, the NHases of both R. erythropolis strains were inducibly produced by addition of epsilon-caprolactam as an inducer.

Amino Acid Sequence↗
PubMed1993

Identification of the cellulose-binding domain of a Bacillus subtilis endoglucanase distinct from its catalytic domain.

The endoglucanase (BSC) from Bacillus subtilis IFO 3034, which shows no ability to hydrolyze microcrystalline cellulose, was found to bind to Avicel. Ninety-eight amino acids-truncation at the COOH-terminus of BSC did not abolish the carboxymethyl cellulose (CMC)-hydrolyzing ability, but removed the Avicel-binding ability. These data suggested the presence of an Avicel-binding domain at the COOH-terminus of BSC, despite its inability to hydrolyze crystalline cellulose. A mutant enzyme with Phe at the 131st His, generated by site-directed mutagenesis, had no enzymatic activity with CMC as the substrate, as predicted from hydrophobic cluster analysis, while the cellulose-binding ability of the mutant enzyme still remained. Similarly, the mutation at the 169th Glu severely affected the enzyme activity, but not the cellulose-binding ability. All these data clearly show that BSC is composed of the catalytic domain at its NH2-terminal portion and the cellulose-binding domain at its COOH-terminal portion, and that the two domains are independently functional in the absence of the other.

Bacillus subtilis↗
PubMed1993

Leptolstatin from Streptomyces sp. SAM1595, a new gap phase-specific inhibitor of the mammalian cell cycle. I. Screening, taxonomy, purification and biological activities.

Leptolstatin, a new inhibitor of the progression of G1 and G2 phases of the mammalian cell cycle, was discovered through a unique screening system, in which effects of microbial metabolites on the cell cycle progression of the cultured rat fibroblasts were monitored by flow cytometry. The new inhibitor was extracted from the fermentation broth of Streptomyces sp. SAM1595 with ethyl acetate, and purified by silica gel column chromatography and HPLC. Leptolstatin showed a strong cytostatic effect on rat normal fibroblasts 3Y1 with an IC50 value of 0.4 ng/ml, but its antimicrobial activity was very weak. A 24-hour treatment of the fibroblast cells with 10 ng/ml of leptolstatin caused an arrest at G1 or G2 phase, as determined by flow cytometry. When the G2-arrested cells were freed from leptolstatin, those containing 4C DNA entered a new S phase without intervening M phase, resulting in the formation of proliferative tetraploid cells.

Animals↗
PubMed1993

Leptolstatin from Streptomyces sp. SAM1595, a new gap phase-specific inhibitor of the mammalian cell cycle. II. Physico-chemical properties and structure.

Leptolstatin, a product from Streptomyces sp. SAM1595, is a gap phase-specific inhibitor of the mammalian cell cycle. Physico-chemical properties and spectrometric analyses showed that the structure of leptolstatin is (2Z,6E,8Z,12E,14E,22E)-19,24-dihydro xy-8,10,14,16,18,20,22-heptamethyl-17-oxo-2 , 6,8,12,14,22-tetracosahexaen-5-olide.

Animals↗
PubMed1993

Immunoreactive hepatocyte growth factor is present in tissue extracts from human breast cancer but not in conditioned medium of human breast cancer cell lines.

Hepatocyte growth factor (HGF) is a novel mitogen for mature hepatocytes. In the present study, we have measured immunoreactive (ir)-HGF concentration in tumor extracts of 82 primary human breast cancers using an enzyme-linked immunosorbent assay (ELISA). Ir-HGF was detectable in all tissue extracts, the concentration ranging from 1.4 to 306.5 ng/100 mg protein (median value: 11.2 ng/100 mg protein). Correlation analyses between ir-HGF concentration and clinicopathological factors showed that the ir-HGF level was significantly higher in tumors with sizes of more than 5.0 cm compared with those less than 5.0 cm. In contrast, no detectable amount of ir-HGF was secreted into culture medium of two breast cancer cell lines, MCF-7 and ZR-75-1, suggesting that the cancer cell itself has no ability to produce ir-HGF.

Breast Neoplasms↗
PubMed1992

Potent and specific inhibition of p60v-src protein kinase both in vivo and in vitro by radicicol.

A fungal metabolite, radicicol, with a macrocyclic ring induced the reversal of transformed phenotypes of v-src-transformed fibroblasts (Rous sarcoma virus-transformed 3Y1 rat fibroblast) at a quite low concentration of 0.1 microgram/ml. Actin stress fibers reappeared in the transformed cells after treatment with radicicol. Radicicol reduced the intracellular level of autophosphorylation of p60v-src as well as the level of other tyrosine-phosphorylated proteins in a dose-dependent manner. In vitro kinase assay revealed that radicicol effectively inhibited not only autophosphorylation but also transphosphorylation activities of purified p60v-src with a concentration producing 50% inhibition of 0.1 microgram/ml. However, radicicol showed no inhibitory effect on protein kinase C or protein kinase A. These results suggest that radicicol is a novel and specific protein-tyrosine kinase inhibitor and that the decreased level of tyrosine kinase activity of p60v-src causes reversion of transformed phenotypes of Rous sarcoma virus-transformed 3Y1 rat fibroblast. Furthermore, differentiation of Friend leukemia cells, which is one of the known characteristic phenomena associated with the inhibition of tyrosine kinase, was also induced in the concentration range of 0.05-0.5 microgram/ml, suggesting that the agent is useful for the analysis of differentiation as well as the kinase-mediated signal transduction.

Animals↗