In vitro establishment of cis-diammine-dichloroplatinum(II) resistant lung cancer cell line and modulation of apoptotic gene expression as a mechanism of resistant phenotype

After exposure of H460 cells to an increasing concentrations of cis-diammine-dichloroplatinum(II) (cisplatin, CDDP) for 6 months, cisplatin resistant cells were isolated (H460/CIS). The biologic behaviors of H460 and H460/CIS cells were tested using animal experiments. Only the resistant cells developed lung metastases despite cisplatin treatment. The characteristics of H460/CIS cells are as follows, MTT analyses revealed that H460/CIS cells were markedly resistant to cisplatin compared with their parental cells. Also, H460/CIS cells exhibited cross-resistance to DNA damaging agents such as doxorubicin (DXR) and etoposide. Cisplatin treatment dramatically increased p53 expression in parental cells but not in H460/CIS cells which expressed basal levels of p53. Without cisplatin treatment, Bcl-2 and Bax were expressed in H460/CIS cells, but not in parental cell. Our data suggested that p53, Bax and Bcl-2 were up-regulated in H460/CIS cells. These changes could explain some of the mechanisms of cisplatin resistance. Thus, H460/CIS could be useful to investigate the mechanisms of drug resistance to cisplatin including apoptotic gene expressions conferring drug resistance, thereby making progress in the treatment of cisplatin-resistant tumor cells.

Semialactone, isofouquierone peroxide and fouquierone, three new dammarane triterpenes from Rhus javanica

Three new dammarane triterpenes and semialactic acid were isolated from the stem bark of Rhus javanica. The structures of these triterpenes, named semialactone, isofouquierone peroxide and fouquierone, were elucidated by 2D-NMR analysis (HMQC, 1H-1H COSY and HMBC), and the 13C-NMR data of semialatic acid is revised.

Inhibitory effect of glycolic acid on ultraviolet-induced skin tumorigenesis in SKH-1 hairless mice and its mechanism of action

Glycolic acid, an alpha-hydroxy acid derived from fruit and milk sugars, has been used commonly as a cosmetic ingredient since it was discovered to have photoprotective and anti-inflammatory effects and antioxidant effects on ultraviolet (UV)B-irradiated skin. Little is known, however, about the functional role of glycolic acid on UV-induced skin tumorigenesis. In the present study, we examined the effect of glycolic acid on UV (UVA + UVB)-induced skin tumorigenesis and assessed several significant contributing factors in SKH-1 hairless mice. Inbred hairless female mice (15 animals/group) were irradiated for 5 d/wk at a total dose of 74.85 J/cm(2) UVA and 2.44 J/cm(2) UVB for 22 wk. Glycolic acid was applied topically twice a week at a dose of 8 mg/cm(2) immediately after UV irradiation. Glycolic acid reduced UV-induced skin tumor development. The protective effect of glycolic acid was a 20% reduction of skin tumor incidence, a 55% reduction of tumor multiplicity (average number of tumors/mouse), and a 47% decrease in the number of large tumors (larger than 2 mm). Glycolic acid also delayed the first appearance of tumor formation by about 3 wk. The inhibitory effect of glycolic acid on UV-induced tumor development was accompanied by decreased expression of the following UV-induced cell-cycle regulatory proteins: proliferating cell nuclear antigen (PCNA), cyclin D1, cyclin E, and the associated subunits cyclin-dependent kinase 2 (cdk2) and cdk4. In addition, the expression of p38 kinase, jun N-terminal kinase (JNK), and mitogen-activated protein kinase kinase (MEK) also was lower in UV + glycolic acid-treated skin compared with expression in UV-irradiated skin. Moreover, transcription factors activator protein 1 (AP-1) and nuclear factor kappaB (NF-kappaB) activation was significantly lower in UV + glycolic acid-treated skin compared with activation in UV-irradiated skin. These results show that glycolic acid reduced UV-induced skin tumor development. The decreased expression of the cell-cycle regulatory proteins PCNA, cyclin D1, cyclin E, cdk2, and cdk4 and the signal mediators JNK, p38 kinase, and MEK may play a significant role in the inhibitory effect of glycolic acid on UV-induced skin tumor development. In addition, the inhibition of activation of transcription factors AP-1 and NF-kappaB could contribute significantly to the inhibitory effect of glycolic acid.

Behavior of murine renal carcinoma cells grown in ectopic or orthotopic sites in syngeneic mice

We examined whether the organ microenvironment modulates the metastatic behavior and the response to doxorubicin (DXR) in murine renal carcinoma (RENCA) cells. Tumor cells were injected into kidney (orthotopic) and subcutis (ectopic) of syngeneic mice. Lung metastases developed in up to 57% (17/30) of animals having kidney tumors but not in those with skin tumors. Tumors growing in the kidney were more resistant to DXR than tumors growing in the subcutis when mice were given intravenous injections of DXR (8 mg/kg) on days 8 and 15 after implantation. In addition, tumor cells cultured from kidney tumors were initially more resistant to DXR than tumor cells cultured from subcutis tumors. After tumor cells were passaged in vitro, all cells exhibited a similar sensitivity to DXR. Additionally, we examined the expression levels of mdr1, EGFR and type IV collagenase by an in situ mRNA hybridization technique. A higher mRNA expression for type IV collagenase and EGFR was found in kidney tumors than in subcutis tumors. These results demonstrate that the organ environment influences the drug responsiveness and the expression of metastasis-related genes in murine renal carcinoma cells.

Activation of mitogen-activated protein kinase pathways by angelan in murine macrophages

In our previous studies, we showed that angelan, a polysaccharide purified from Angelica gigas Nakai, specifically activated macrophages to induce cytokines including inducible nitric oxide synthase (iNOS) which has strong anti-tumor activities [Immunopharmacology, 1999; 43: 1.]. In the present study, we investigated the intracellular signal transduction pathways involved in the angelan-induced iNOS synthesis by murine macrophages. Protein tyrosine phosphorylation was induced within 5 min by angelan, and the blocking of protein tyrosine kinases (PTKs) inhibited down-stream pathways leading to iNOS production in response to angelan. Treament of RAW 264.7 cells with angelan resulted in significant activation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and p38, while stress-activated protein kinase/c-Jun NH2 terminal kinase (SAPK/JNK) was not activated by angelan. The specific p38 inhibitor SB203580 abrogated the angelan-induced iNOS synthesis, whereas the selective mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase 1 (MEK-1) inhibitor PD98059 did not affect the iNOS induction. In conclusion, we demonstrate that PTK and p38 MAPK activation are required to transduce signals leading to iNOS expression in angelan-stimulated murine macrophages.

Characterization of the 16S rRNA gene V2 region and the rrn operons of Gardnerella vaginalis

Ribosomal RNA (rRNA) gene polymorphism was apparent when Gardnerella vaginalis DNA restriction profiles were hybridized with nonradioactively labeled total rRNA isolated from this bacterium. In contrast, use of a polymerase chain reaction (PCR)-based 16S rRNA gene V2 region resulted in a 118-bp V2-PCR amplicon that was specific and common in all 30 tested G. vaginalis isolates. In addition to providing a G. vaginalis-specific fingerprint, when the V2-PCR amplicon along with total rRNA were utilized as probes, a partial rRNA gene restriction map could be constructed. G. vaginalis contains two rrn operons with an EcoRI fragment of 1.6 kb common to both.

Inhibitory activity of stilbenes from medicinal plants on the expression of cell adhesion molecules on THP1 cells

The inhibitory activity of stilbenes isolated from medicinal plants on cell adhesion molecules on the surface of THP-1 human monocytic cell lines was investigated. Among ten stilbenes tested, four stilbenes displayed a significant inhibitory activity on the expression of both intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). A cell-to-cell adhesion assay showed that 3,5-dihydroxy-4'-methoxystilbene and 2,3,4',5-tetrahydroxystilbene-2-O-beta-D-glucopyranoside as well as resveratrol blocked significantly TNF-alpha-inducing cell-cell adhesion between human umbilical vein endothelial cells (HUVEC) and THP-1 cells.

Differential activation of murine macrophages by angelan and LPS

In our previous studies, we showed that angelan, a polysaccharide purified from Angelica gigas Nakai, is a potent LPS-mimetic in murine macrophages [Jeon, Y.J., Han, S.B., Ahn, K.S., Kim, H.M., 1999. Activation of NF-kB/Rel in angelan-stimulated macrophages. Immunopharmacology 43, 1-9]. Angelan stimulates murine macrophage to produce cytokines including iNOS and activate NF-kappaB/Rel. In the present study, we investigated the role of CD14 and complement receptor type 3 (CR3) in mediating NO production and NF-kappaB/Rel activation induced by angelan and LPS. Three major differences between angelan and LPS were observed. First, angelan does not require serum proteins for NO response and NF-kappaB/Rel activation, while the activation by LPS requires serum proteins. Second, blocking of either CD14 or CR3 decreased angelan-induced NO response, while LPS-mediated NO production was inhibited by anti-CD14 mAb only. Third, angelan induced strong NF-kappaB/Rel and slight AP-1 DNA binding, whereas LPS potently activated both NF-kappaB/Rel and AP-1. Both angelan and LPS degraded IkappaB proteins and subsequently induced the mobilization of NF-kappaB/Rel proteins (p65, c-rel and p50) into nucleus. This suggests that macrophages display a common signaling machinery leading to the NF-kappaB/Rel activation in response to different stimulants. In conclusion, angelan and LPS use the membrane receptor CD14 and CR3 differentially for signaling NF-kappaB/Rel activation and NO production.

Effects of triterpenoids from Pueraria lobata on immunohemolysis: beta-D-glucuronic acid plays an active role in anticomplementary activity in vitro

The anticomplementary properties of kaikasaponin III (4) and soyasaponin I (8) from Pueraria lobata and their hydrolytic analogs were investigated in vitro. Diglycosidic saponins [kaikasaponin I (3), soyasaponin III (7)] showed most potent anticomplementary activities, followed by monoglycosidic saponins [soyasapogenol B monoglucuronide (6), sophoradiol monoglucuronide (2)] and triglycosidic saponins [soyasaponin I (8), kaikasaponin III (4)], whereas sophoradiol (1) and soyasapogenol B (5) showed enhancement of hemolysis under the presence of serum on the classical pathway of complement system. But all of them showed very weak or no anticomplementary activities on the alternative pathway of complement system. The anticomplementary activity of the saponins was influenced by the nature of glucuronic acid, where the free acid forms (-COOH) showed much more potent activity than the sodium salt forms (-COO-Na+) or methyl ester forms (-COOCH3), and the reduced forms (-CH2OH) decreased the activity significantly.

Enhanced induction of Bax gene expression in H460 and H1299 cells with the combined treatment of cisplatin and adenovirus mediated wt-p53 gene transfer

Cytotoxic effect of either cisplatin or p53 gene transfection of lung cancer cells may be different depending on the p53 status of cells. We investigated cytotoxic effects on the combined treatment of cisplatin and adenovirus mediated p53 gene transfer (Avp53) in both H460 and H1299 cells in vitro. The results showed the highest numbers of apoptotic cells in both H460 and H1299 cells following the combined treatment regardless of p53 status in comparison with either cisplatin or Avp53 alone. The expression levels of p53, p21, Bax and ICE were examined to understand a possible cellular signal path of the combined treatment. In western analyses, the patterns of phosphorylated p53 protein were different between Avp53 and combined treatment. The expressions of p21 and Bax were increased in combined treatment, whereas the cleaved form of ICE (20 kD) was not detected. These results suggest that cisplatin induced p53 protein phosphorylation and may activate the downstream of p53 gene expression such as p21 and Bax. The enhanced apoptosis of lung cancer cells by the combined treatment may be useful in the development of clinical therapeutic modality of lung tumors.

Cloning, nucleotide sequence and expression of thioltransferase (glutaredoxin) cDNA from Schizosaccharomyces pombe

Thioltransferase (TTase), also known as glutaredoxin (Grx), is an enzyme that catalyzes the reduction of a variety of disulfide compounds, including protein disulfides, in the presence of reduced glutathione. TTase acts as a cofactor for various enzymes such as ribonucleotide reductase. We previously purified a TTase from Schizosaccharomyces pombe and its molecular size was determined. In the present study, a cDNA coding TTase was isolated from a cDNA library of Schizosaccharomyces pombe by colony hybridization, which was constructed in a plasmid vector pGAD GH, and its corresponding insert was confirmed by Southern hybridization. The nucleotide sequence of the 375 bp long cDNA clone reveals an open reading frame, which encodes a protein of 101 amino acids. The coding region of the original clone was transferred after the lac promoter of pUC13 vector for expression in E. coli, and simultaneously, a suitable Shine-Dalgarno (SD) sequence was added in front of the coding region by PCR. The two primers used for PCR also separately contained BamHI and HindIII restriction sites. The E. coli strain (A434) harboring the pUC13 derivative pKU10 showed a 17.3-fold increase in TTase activity compared to the strain with only the vector plasmid.

Acylated flavonol glycosides with anti-complement activity from Persicaria lapathifolia

During a search for biologically active compounds from traditional medicines, a crude extract of Persicaria lapathifolia was found to have anti-complement activity. Bioassay-guided chromatographic separation of the active constituents led to the isolation of a new acylated kaempferol glycoside (1) and three known acylated quercetin glycosides (2-4). The structures of compounds 1-4 were characterized as kaempferol 3-O-beta-D-(6"-p-hydroxybenzoyl)-galactopyranoside, quercetin 3-O-beta-D-(6"-feruloyl)-galactopyranoside, quercetin 3-O-beta-D-(2"-galloyl)-rhamnopyranoside and quercetin 3-O-beta-D-(2"-galloyl)-glucopyranoside, respectively. Compounds 1-4 showed strong anti-complement activity (IC50 values of 4.3, 9.7, 3.9 and 7.6 x 10(-5) M, respectively) on the classical pathway of the complement. On the other hand, six isolated flavonol glycosides (5-10) did not show any activity on this system.

Anticomplement activities of oleanolic acid monodesmosides and bisdesmosides isolated from Tiarella polyphylla

Seven known oleanolic acid glycosides (1-7) were isolated from the MeOH extract of Tiarella polyphylla. The structures were identified to be 3-O-(beta-D-glucopyranosyl) oleanolic acid (1), 3-O-[beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl] oleanolic acid (2), 3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl] oleanolic acid (3), 3-O-[beta-D-glucopyranosyl-(1-->3)-beta-D-glucopyranosyl] oleanolic acid 28-O-beta-D-glucopyranosyl ester (4), 3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl] oleanolic acid 28-O-beta-D-glucopyranosyl ester (5), 3-O-[a-L-rhamnopyranosyl-(1-->3)-beta-D-glucuronopyranosyl] oleanolic acid (6), and 3-O-[alpha-L-rhamnopyranosyl-(1-->3)-beta-D-glucuronopyranosyl] oleanolic acid 28-O-beta-D-glucopyranosyl ester (7) on the basis of physicochemical and spectral data. These triterpene glycosides were tested for the anticomplement activity and hemolytic activity. Bisdesmosidic saponins, 4, 5, and 7, showed anticomplement activity; in contrast, monodesmosidic saponins, 1-3, and 6, showed direct hemolytic activity. Methyl esterified monodesmosidic saponins showed anticomplement activity at a low concentration and hemolytic activity at a high concentration.

In vitro anticomplementary activity of hederagenin saponins isolated from roots of Dipsacus asper

Anticomplementary activity of hederagenin and related saponins isolated from Dipsacus asper was investigated in vitro. HN saponin F (3) was most potent with IC50 value of 3.7x10(-5) M followed by 3-O-beta-D-glucopyranosyl-(1->3)-alpha-L-rhamnopyranosyl-(1->2)-beta-L-+ ++arabi nopyranosyl hederagenin 28-O-beta-D-glucopyranosyl-(1->6)-beta-D-glucopyrano side (8), 3-O-beta-L-arabinopyranosyl hederagenin 28-O-beta-D-glucopyranosyl-(1->6)-beta-D-glucopyranoside (5), dipsacus saponin A (4), and hederagenin (1) on the classical pathway (CP) of complement system, while the saponins 3-5 did not show the inhibition of hemolysis and rather increase the hemolysis on the alternative pathway (AP). However, all of C-3 monodesmosides [prosapogenin CP (2), dipsacus saponin B (6), and dipsacus saponin C (7)] evoked hemolysis directly on the erythrocytes.

Activation of NF-kappaB/Rel in angelan-stimulated macrophages

In our previous studies we showed that the primary target cell of angelan, a polysaccharide purified from Angelica gigas Nakai, is a macrophage (Han et al., 1998). In the present study we examined the effect of angelan on iNOS, IL-1beta, and TNF-alpha transcription in mouse macrophage line RAW 264.7. We show that angelan produces a marked induction of iNOS, IL-1beta, and TNF-alpha transcription by RAW 264.7 cells. Since these gene transcriptions have been recently shown to be under the control of NF-kappaB/Rel family of transcription factors, we assessed the effect of angelan on NF-kappaB/Rel using a electrophoretic mobility shift assay. Treatment of RAW 264.7 cells with angelan produced strong induction of NF-kappaB/Rel binding. Treatment of RAW 264.7 cells with angelan slightly induced AP-1 binding activity, whereas Oct binding was not affected by angelan. Angelan stimulated macrophages to activate NF-kappaB/Rel, whereas neither B-cells nor T-cells were affected by the angelan. In conclusion, we demonstrate that the stimulation effect of angelan on macrophage is mediated by specific activation of NF-kappaB/Rel.

Structure-activity relationships of lignans from Schisandra chinensis as platelet activating factor antagonists

We studied the structure-activity relationships of lignans from Schisandra chinensis and their derivatives as platelet activating factor (PAF) antagonists. Strong activity was shown in lignans without an ester group at C-6, a hydroxyl group at C-7 or a methylene dioxy moiety and with an R-biphenyl configuration. 6(7)-Dehydroschisandrol A, a derivative of schisandrol A, showed the highest activity (IC50, 2.1x10(-6) M) in this study.

Anti-complement activity of tiliroside from the flower buds of Magnolia fargesii

As part of the search for anticomplementary active components from natural products, the anticomplementary properties of methanolic extracts from the flower buds of Magnoliafargesii have been investigated. Bioassay-guided chromatographic separation of the active constituents led to the isolation of compound 1, whose structure was identified by spectroscopic methods to be kaempferol 3-O-beta-D-(6"-O-coumaroyl)glucopyranoside (tiliroside). Tiliroside showed very potent anti-complement activity (IC50=5.4 x 10(-5) M) on the classical pathway of the complement system, even higher than rosmarinic acid, which is a well-known inhibitor against the complement system. On the other hand, the hydrolysates of tiliroside, kaempferol, astragalin and p-coumaric acid showed very weak activity on this system.

Characteristic immunostimulation by angelan isolated from Angelica gigas Nakai

The immunopharmacological characteristics of angelan, a polysaccharide purified from Angelica gigas Nakai, were investigated in relation to the specificity to immune cells. The treatment of angelan increased the expression of IL-2, IL-4, IL-6, and IFN-gamma. The expression of IL-6 and IFN-gamma was rapidly augmented but that of IL-2 responded later. In the case of IL-4, angelan stimulated at early time after exposure but down-regulated thereafter. These results suggested that macrophages and natural killer cells involved in nonspecific immunity were primarily activated and helper T cells were secondarily affected by angelan. Angelan also had lympho-proliferative potential to B cells, specifically. The specificity of angelan was also elucidated in a cell fractionation experiment. The activated B cells by angelan also increased antibody production. The direct activation of B cells, macrophages, and accessory cells and the indirect activation of helper T cells coordinately increased immune functions such as in vitro and in vivo T-dependent immunization and antibody production. The experiment of host resistance to syngeneic tumors also showed that angelan potentiated the immune functions. In conclusion, angelan, a purified polysaccharide from an oriental herbal drug, showed characteristic immunostimulation, which was different from clinically used polysaccharides such as lentinan and PSK.

Corosolic acid isolated from the fruit of Crataegus pinnatifida var. psilosa is a protein kinase C inhibitor as well as a cytotoxic agent

Corosolic acid isolated from the fruit of Cratoegus pinnatifida var. psilosa was tested for anticancer activity. Corosolic acid displayed about the same potent cytotoxic activity as ursolic acid against several human cancer cell lines. In addition, the compound displayed antagonistic activity against the phorbol ester-induced morphological modification of K-562 leukemic cells, indicating the suppression of protein kinase C (PKC) activity by the cytotoxic compound. The compound showed PKC inhibition with dose-dependent pattern in an in vitro PKC assay.

Decursinol angelate: a cytotoxic and protein kinase C activating agent from the root of Angelica gigas

A cytotoxic compound was purified from the root of Angelica gigas Nakai by normal phase HPLC. As a result of the structure analysis by mass, IR, 1H-NMR, and 13C-NMR spectrometry, the compound was identified as decursinol angelate, a structural isomer of decursin, and characterized originally from Sesei grandivittatum. Decursinol angelate showed in vitro cytotoxicity and protein kinase C activating activities like decursin.

Nucleotide sequence and developmental expression of Acanthamoeba S-adenosylmethionine synthetase gene

We have isolated and characterized a cDNA (cDNA1) from an Acanthamoeba cDNA library encoding the enzyme S-adenosylmethionine (SAM) synthetase (ATP: L-methionine S-adenosyltransferase; EC 2.5.1.6). The nucleotide sequence exhibits about 61-73% overall similarity to the corresponding gene of other organisms. The cDNA displays extreme codon bias with a preference for C or G in the third position. A putative initiation site and an ATP-binding site are identified. An amino acid content of 388 and a molecular mass of about 44,000 Daltons are deduced for the enzyme. Putative phosphorylation sites which might be involved in regulation of the enzyme are revealed. The cDNA was expressed in Escherichia coli BL21(DE3), and the identity of the protein product confirmed by Western blotting analysis. Northern analyses of the expression of the Acanthamoeba SAM synthetase gene during development revealed a pronounced reduction in the level of transcripts as amoebae converted to cysts.

Decursin: a cytotoxic agent and protein kinase C activator from the root of Angelica gigas

A cytotoxic compound was purified from the root of Angelica gigas Nakai by silica gel chromatography and preparative HPLC. As a result of the structure analysis by mass, IR, 1H-NMR, and 13C-NMR spectrometry, the effective compound was identified as decursin, a pyranocoumarin characterized originally from Angelica decursiva Fr. et Sav. In vitro cytotoxicity testing showed that decursin displayed toxic activity against various human cancer cell lines, for which the ED50 of decursin was about 5-16 micrograms/ml. On the other hand, decursin displayed relatively low cytotoxicity against normal fibroblasts. Decursin also activated protein kinase C (PKC) in vitro, which indicates that the cytotoxic activity of decursin may be related to the protein kinase C activation.

Electronic dental anesthesia versus topical anesthesia for the control of pain caused by nasopalatine block injections

Topical anesthetics are routinely used to reduce the pain and discomfort that patients may experience during dental injections. Just recently, however, an anesthesia (Electronic Dental Anesthesia or EDA) which works by transcutaneous electrical nerve stimulation (TENS) was introduced to the dental profession. The purpose of this study was to determine whether an electrical signal as provided by an EDA is more effective than topical anesthesia in reducing pain and discomfort caused by local anesthetic injections. Two nasopalatine block injections, one using and EDA as the adjunct, and the other using a topical anesthetic ointment of Xylocaine 5% were performed on thirty-four patients. The volunteers were asked on the spot to report the level of the pain they felt during the penetration of the needle to the mucosa, during the deposition of local anesthetic solution, and their overall evaluation of the injections. The results of this investigation showed that the EDA is the more effective adjunct for local anesthetic injections compared to the traditional topical anesthetics.

An Acanthamoeba ubiquitin-fusion protein; cDNA and deduced protein sequence

We have isolated and sequenced a 525 bp ubiquitin cDNA (Acantub1) from the soil amoeba Acanthamoeba castellanii. The deduced amino acid (aa) sequence reveals that the Acantub1 gene product is a fusion protein consisting of 128 aa (76 aa ubiquitin and 52 aa 60S ribosomal protein). The Acantub1 protein sequence has unique substitutions at aa 28 (glutamine for alanine) and 121 (tryptophan for leucine) compared to the 8 highest homologous sequences in the databank. A putative 'zinc finger' nucleic acid-binding domain was located in the 52 aa ribosomal protein. Northern analyses reveal that the Acantub1 gene is regulated during development.

Autoregulation of the gene encoding the replication terminator protein of Bacillus subtilis

One of two putative sigma A promoters identified previously in the region immediately upstream from the rtp gene (encoding the replication terminator protein) [Smith and Wake, J. Bacteriol. 170 (1988) 4083-4090] has been shown by transcription start point (tsp) mapping to be the functional rtp promoter. In these tsp mapping experiments, it was observed that the level of mRNA from this promoter, Prtp, was increased by a factor of 30 in the absence of the replication terminator protein (RTP), consistent with the autoregulation of rtp at the level of transcription. In vitro transcription from Prtp by sigma A RNA polymerase has been shown to be specifically repressed by RTP. A Prtp-spoVG-lacZ fusion was inserted into the chromosome of a strain in which RTP production was inducible by IPTG. Addition of IPTG to cultures of the new strain lowered beta Gal production by a factor of at least four. It is concluded that rtp is autoregulated in vivo at the level of transcription.

Variations and coding features of the sequence spanning the replication terminus of Bacillus subtilis 168 and W23 chromosomes

In a comparative study of the sequences of the 3-kb regions of DNA spanning the replication terminus, terC, of Bacillus subtilis strains 168 and W23, it was found that the latter contained an insertion of a large open reading frame (ORF405) whose translated protein product is a member of the cytochrome P-450 family. The insertion was about 34 nucleotides upstream from a putative promoter for the rtp gene. The sequenced regions contained a number of other ORFs. The translation product of one (ORF238) is a member of a previously identified oxidoreductase superfamily. The translation product of another (ORF257) is significantly similar to the proC product of Escherichia coli, but this ORF does not code for a functional proC product of B. subtilis.