Molecular breeding of the basidiomycete Coprinus cinereus strains with high lignin-decolorization and -degradation activities using novel heterologous protein expression vectors

Two chromosome-integrating vectors, pLC1 and pLC2, were used. The former is the pUC19-based vector carrying the Lentinus edodes ras gene promoter and priA gene terminator, and the latter is the pBR322-based vector carrying the promoter and terminator of the priA gene. The manganese (II) peroxidase (MnP) cDNA (mnpc) derived from Pleurotus ostreatus was fused between the promoter and terminator of pLC1 and pLC2, yielding the recombinant plasmids pLC1-mnp and pLC2-mnp. These plasmids were introduced into protoplasts of the Coprinus cinereus trp1 strain with the C. cinereus TRP1-containing plasmid pCc1001 by co-transformation. Two Trp+ transformants for each plasmid, showing clearly higher lignin-decolorization activities, were obtained through introduction of pLC1-mnp and pLC2-mnp. Southern-blot analysis revealed that the four transformants all possess the mnpc sequence on their chromosomes. One Trp+ MnP+ transformant (named TF2-7), which was derived from the introduction of pLC2-mnp and carried the highest number of copies (approx. 10) of mnpc, showed remarkably high lignin-decolorization and -degradation activities; at the time of cultivation when only 35%-40% of the lignin was decolored and degraded by the control Trp+ transformant obtained by the introduction of pCc1001 alone, almost all of the lignin was decolored and degraded by TF2-7.

Determination of the DNA-binding sequences of the Zn(II)2Cys6 zinc-cluster-containing PRIB protein, derived from the basidiomycete Lentinus edodes gene

The 565 amino-acid PRIB protein with a Zn(II)2Cys6 zinc-cluster DNA-binding motif is the expression product of the priB gene, which is most actively transcribed in an early stage of fruiting-body formation by the basidiomycete, Lentinus edodes. PRIB produced in Escherichia coli using the bacteriophage T7 expression system was purified by ion-exchange chromatographies and then subjected to random binding-site selection analysis using a pool of random 24-bp oligonucleotides with 13-bp PCR primer sites at each end. The oligonucleotides (50 bp) selected for PRIB binding were cloned into pUC19. A total of 303 cloned DNA fragments were picked randomly and sequenced. The PRIB binding sites could be grouped into 25 individual sequences, suggesting a consensus sequence of 16 bp, 5' GGGGGGGACAGGANCC 3'. Gel mobility-shift assaying of 10 randomly selected sequences all revealed a reasonable band shift. DNase I footprinting analysis of the 50-bp DNA fragment containing the sequence most similar to the consensus sequence showed that PRIB protects the entire 16-bp sequence from digestion by DNase I.

Structure and function in Escherichia coli of plasmids containing pyrimidine/purine-biased stretch originated from the 5'-flanking region of the basidiomycete ras gene

The Basidiomycete ras gene possesses a pyrimidine-rich stretch (CT-motif) with a short (7 bases) mirror repeat in which its major transcription start point is contained. To analyze the tertiary structure induced by the CT/AG-biased sequence and its effect on gene expression in supercoiled plasmids in Escherichia coli, the DNA fragment containing the ras CT/AG sequence was inserted into the EcoRI site on pBR322 in both orientations and the resulting pBR322 derivatives, named pBR-CT[ras] and pBR-invCT[ras] were introduced into E. coli strains DM800 (deltatopA gyrB225) and JM109 (topA+ gyrA96). In pBR-CT [ras] the pyrimidine-rich sequence is on the pBR322 tetracycline-resistance gene (tet)coding strand and in pBR-invCT[ras] the complementary purine-rich sequence is on this strand. DNAs of pBR-CT[ras] and pBR-invCT[ras] isolated from DM800 were frequently cleaved with single-strand-specific S1 nuclease within the CT/AG sequence, showing the formation of extended open structure. Compared with those carrying pBR322, DM800 and JM109 carrying pBR-CT [ras] showed much higher levels of tetracycline resistance (Tcr), while both strains carrying pBR-invCT[ras] showed clearly lower levels of Tcr. pBR-CT [ras] and pBR-invCT [ras], however, conferred reduced activity of beta-lactamase on DM800 and JM109. pBR-CT [ras] derivatives lacking the counterpart of the mirror repeat did not form the S1-cleavable open structure within the CT/AG sequence and conferred pBR322-like Tcr and beta-lactamase activity. The tertiary structure formed in the CT/AG sequence via the mirror repeat was suggested to affect the expressions of pBR322-tet and -bla genes.

Aggregation of yeast cells induced by the Arg-Gly-Asp motif-containing fragment of high-molecular-mass cell-adhesion protein MFBA, derived from the basidiomycetous mushroom Lentinus edodes

A fruiting body-specific cDNA mfbAc, derived from the basidiomycete Lentinus edodes, has been shown to encode a high-molecular-mass (2157 amino acids) cell-adhesion protein MFBA containing the Arg-Gly-Asp (RGD) motif. A 425-amino-acid fragment containing the RGD motif of MFBA (designated MFBA(582-1006) peptide) produced in Escherichia coli exhibited cell-adhesion and spreading activity toward mammalian cells and cell-aggregation activity toward basidiomycetous hyphal cells via the RGD sequence. Here we investigated the biological activity of MFBA(582-1006) peptide in Saccharomyces cerevisiae. The DNA sequence encoding MFBA(582-1006) peptide, introduced into the yeast using an expression vector, resulted in a marked aggregation of the yeast cells. The aggregation was almost completely abolished by replacement of the RGD motif by an RGE motif in the peptide sequence.

Generation of basidiomycetous hyphal cell-aggregates by addition of the Arg-Gly-Asp motif-containing fragment of high-molecular-weight cell-adhesion protein MFBA derived from the basidiomycete Lentinus edodes

The Arg-Gly-Asp (RGD) motif-containing fragment of high-molecular-weight cell-adhesion protein MFBA derived from Lentinus edodes caused a significant aggregation of the fragmented hyphal cells of Schizophyllum commune. This fungal cell-aggregation was inhibited by a previous treatment of the cells with the Gly-Arg-Gly-Asp-Ser-Pro peptide, but not with the Gly-Arg-Gly-Glu-Ser-Pro peptide, showing that the RGD motif is essential for the cell-aggregation activity.

Evaluation of mRNAs encoding muscarinic receptor subtypes in human detrusor muscle

PURPOSE

The present study evaluated the muscarinic receptor subtypes corresponding to m1 to m5 genes in human detrusor muscle.

MATERIALS AND METHODS

The mRNAs encoding m2 and m3 subtypes were assessed by reverse transcription (RT)-polymerase chain reaction (PCR). The amounts of cDNA synthesized from m2 and m3 mRNAs were measured by using subcloned plasmid DNAs. The distribution of m2 and m3 mRNAs in detrusor was estimated by comparing the amount of m2 cDNA with that of m3 cDNA.

RESULTS

The m2 mRNA:m3 mRNA ratio was 1.06:1.00 in human detrusor. In the cryostat sections of human detrusor, the presence of both m2 and m3 mRNAs was confirmed by in situ hybridization. However, the RT-PCR products derived from m1, m4 and m5 subtype mRNAs were not detected.

CONCLUSION

These results suggest that human detrusor muscle coexpresses muscarinic m2 and m3 receptors and that the populations of the 2 subtypes are not significantly different.

The integrative transformation of Pleurotus ostreatus using bialaphos resistance as a dominant selectable marker

A plasmid pLC-bar containing the bialaphos resistance gene derived from Streptomyces hygroscopicus between the Lentinus edodes ras gene promoter and priA gene terminator was constructed. When protoplasts of Pleurotus ostreatus were mixed with the plasmid DNA in the presence of polyethylene glycol and CaCl2, bialaphos-resistant colonies were obtained. This indicated that transformation was successful. Southern blot analysis of total DNAs from transformants showed that the introduced plasmid DNA was integrated into the host chromosome and partly rearranged. A plasmid, pLC-GUS, containing the Escherichia coli beta-glucuronidase (GUS) gene under the control of the L. edodes ras gene promoter and priA gene terminator was constructed and introduced into protoplasts of P. ostreatus with pLC-bar by co-transformation. Two of 5 transformants obtained as bialaphos-resistant colonies showed two to twenty times higher specific activity of GUS than the recipient. Southern blot analysis of total DNAs from transformants indicated the presence of the GUS gene only in the two transformants. These results indicated that co-transformation of P. ostreatus was successful, and that the GUS gene was expressed in P. ostreatus. This transformation system will enable us to breed commercial strains of P. ostreatus at the molecular level.

The effects and pharmacokinetics of rhG-CSF in patients with chronic renal failure

The pharmacokinetics and effects of recombinant human granulocyte colony-stimulating factor (rhG-CSF) on neutrophils and immunological function were studied in 10 patients with end-stage renal failure. A single dose and 2-week consecutive dosing of 50 micrograms/m2 of rhG-CSF were drip infused intravenously, and plasma rhG-CSF levels, peripheral blood cell counts, coagulation, and neutrophil and immunological functions were determined during treatment. The mean half-life of rhG-CSF in patients (2.47 +/- 0.64 h) was prolonged to about twice that of healthy subjects, and hemodialysis did not affect the pharmacokinetics. A marked increase in neutrophils and a slight increase in lymphocytes were observed with the single and consecutive administration of rhG-CSF, but no significant changes were noted in other leukocyte fractions and erythrocyte and platelet counts. The neutrophil alkaline phosphatase value increased significantly following rhG-CSF administration, and other neutrophil functions were also ameliorated in several patients with neutrophil dysfunction. In consecutive administration, however, mild bone pain and increased serum alkaline phosphatase were observed in about half the patients, but neither accumulation of rhG-CSF nor antibody production was detected. From these results, it is concluded that rhG-CSF is safe and effective for the treatment of neutropenia and neutrophil dysfunction in patients with renal failure.

Bacillus subtilis strains carry highly homologous direct repeat sequences on their chromosomes

Highly homologous 170-bp sequences were found to be carried in the same orientation by the chromosomes of Bacillus subtilis GSY908 (a 168 derivative), B. subtilis R, and B. subtilis var. natto. These sequences were in 5'- and 3'-flanking regions of a tetracycline-resistance determinant in B. subtilis GSY908 and B. subtilis R.

Characterization of the promoter region of a cell-adhesion protein gene derived from the basidiomycete Lentinus edodes

An analysis of the 2 kb nucleotide sequence including the 5'-flanking region of a cell-adhesion protein-encoding gene (mfbA) isolated from the basidiomycete Lentinus edodes revealed that the promoter region contains a TATA box, a GC box, a CAAT box, a CT-rich sequence element, a TATA box, two CT-rich sequences, and a CAAT box, in the order, from upstream to downstream. Three major and three alternative transcriptional initiation sites were located 127, 129 and 131 nucleotides and 96, 193 and 197 nucleotides downstream from the downstream TATA box, and all the three major sites are positioned just in the most downstream CT-rich sequence. Three 16 bp unique sequences similar to the binding sites of Neurospora crassa transcriptional activator protein qa-1F (Baum et al. (1987) Expression of qa-1F activator protein: Identification of upstream binding sites in the qa gene cluster and localization of the DNA-binding domain. Mol. Cell. Biol. 7, 1256-1266) were present between the upstream TATA box and upstream CAAT box.

A fruiting body-specific cDNA, mfbAc, from the mushroom Lentinus edodes encodes a high-molecular-weight cell-adhesion protein containing an Arg-Gly-Asp motif

A cDNA clone (designated mfbAc), encoding 2157 amino acids (aa), was isolated from a mature fruiting-body cDNA library of the edible mushroom Lentinus edodes. The mfbA transcript was abundant in mature fruiting bodies, detectable in immature fruiting bodies but absent in earlier developmental stages and in the vegetative mycelium. Although more abundant in the pileus than the stipe, only low levels were found in the gill tissue. The deduced MFBA protein (234.5 kDa) contained a cell-surface attachment-promoting Arg-Gly-Asp (RGD) motif. MFBA was produced in Escherichia coli using a maltose-binding protein (MBP) fusion vector, but it was cleaved into four fragments even in a protease-deficient host. A 425-aa MFBA peptide containing the RGD motif (named MFBA(582-1006) peptide) was successfully produced using the phage T7 expression system. This MFBA(582-1006) peptide exhibited a cell adhesion and spreading activity toward mammalian cells. This activity of the MFBA fragment was competitively inhibited by the Gly-Arg-Gly-Asp-Ser-Pro peptide but not by the Gly-Arg-Gly-Glu-Ser-Pro peptide, showing that the RGD motif of MFBA is essential for the cell-binding activity.

Presence of Active and Inactive Molecules of a Cell Wall-Associated Proteinase in Lactobacillus helveticus CP790

Monoclonal antibodies against a cell wall-associated 45-kDa proteinase from Lactobacillus helveticus CP790 were prepared and used for an immunoblotting analysis of the cell wall extract of CP790. They were found to react with an unidentified 46-kDa protein as well as the 45-kDa proteinase. The 46-kDa protein was copurified with the 45-kDa proteinase by affinity column chromatography using antibody-fixed Sepharose and sodium dodecyl sulfate-polyacrylamide gel electrophoresis and then extracted from the gels. An elution profile of the cyanogen bromide digest of the purified 46-kDa protein obtained by reversed-phase high-performance liquid chromatography was identical to that of the 45-kDa proteinase except for one peak. An analysis of the N-terminal 21-amino-acid sequence revealed that the 46-kDa protein possesses an extra 7 amino acids at the N terminus of the 45-kDa proteinase. The 46-kDa protein was produced at constant levels during fermentation in a skim milk medium, while the 45-kDa protein was mainly observed in the middle of the exponential phase of growth and was produced in proportion to the proteinase activity. Moreover, only the 46-kDa protein was detected in the crude extract of L. helveticus CP791, a variant strain of CP790 defective in proteinase activity. These data strongly suggest that the 46-kDa protein is a precursor, inactive form of the 45-kDa proteinase.

A novel cDNA, priBc, encoding a protein with a Zn(II)2Cys6 zinc cluster DNA-binding motif, derived from the basidiomycete Lentinus edodes

A cDNA clone (designated priBc) was isolated from a primordial cDNA library of the basidiomycete, Lentinus edodes (Le). The priBc clone consisted of 2628 bp encoding 565 amino acids. As was expected, the priB transcript was abundant in primordia, while preprimordial mycelia and mature fruiting bodies contained lower levels of this Le transcript. The deduced PRIB protein (64 kDa) contained a 'Zn(II)2Cys6 zinc cluster' DNA-binding motif. PRIB was produced in Escherichia coli using the bacteriophage T7 expression system. Southwestern blot analysis revealed that PRIB binds to the DNA fragment containing the upstream region of priB.

Clinical study of audiograms in the initial stage and fixed stage of sudden deafness

Audiograms in the initial stage and the fixed stage of sudden deafness were analyzed in 79 cases using the following 5 criteria; i) the onset is sudden and time of onset definite, ii) hearing loss at 1 kH is more than 35 dB, iii) the course of hearing recovery is clear, iv) unaffected ear has normal hearing, and v) the first examination and treatment is within 15 days after onset. Consequently, at least in cases receiving treatment within 6-15 days after onset, it was considered that the prognosis of hearing recovery could be established rather than the pattern of hearing loss than by the period of treatment after onset.

Basidiomycetous ras cDNA functionally replaces its homolog genes in yeast

It was shown by a plasmid exchange procedure that the Ras-encoding cDNA of the basidiomycete Lentinus edodes (named Leras cDNA) can functionally replace its homolog genes (ScRAS1 and ScRAS2) in the yeast Saccharomyces cerevisiae to maintain the viability of an yeast strain containing genetic disruptions of both RAS genes. The strain replaced by a Leras-cDNA-carrying plasmid, however, grew slower than the strains replaced by a ScRAS1- or a ScRAS2-carrying plasmid. The intracellular level of cAMP in the strain harboring the Leras-cDNA-carrying plasmid was clearly higher than that of a parental strain which maintains a plasmid carrying the S. cerevisiae cAMP-dependent protein kinase catalytic subunit C1 gene, TPK1, but was lower than that in a strain harboring an ScRAS2-carrying plasmid. These results suggest that the Leras cDNA can complement the ras1- ras2- mutation of yeast by virture of the stimulation of adenylate cyclase activity, although the complementation is not as efficient as that obtained by expressing the ScRAS2 gene.

Nucleotide sequence of a ras gene from the basidiomycete Coprinus cinereus

The basidiomycete Lentinus edodes (Le.) ras gene (or its cDNA clone) [Hori et al., Gene 105 (1991) 91-96] was utilized to identify and clone the corresponding gene (Cc.ras)-containing genomic fragment from the basidiomycete, Coprinus cinereus. Cc.ras encodes 215 amino acids (aa) interrupted by six small introns. The deduced Cc.RAS protein exhibits significant homology (84.7% identical) to the Le.RAS protein (217 aa) in size and aa sequence.

Bending of DNA segments with Saccharomyces cerevisiae autonomously replicating sequence activity, isolated from basidiomycete mitochondrial linear plasmids

Previous studies have indicated that DNA bending is a general structural feature of sequences (ARSs) from cellular DNAs of yeasts and nuclear and mitochondrial genomic DNAs of other eukaryotes that are capable of autonomous replication in Saccharomyces cerevisiae. Here we showed that bending activity is also tightly associated with S. cerevisiae ARS function of segments cloned from mitochondrial linear DNA plasmids of the basidiomycetes Pleurotus ostreatus and Lentinus edodes. Two plasmids, designated pLPO2-like (9.4 kb), and pLPO3 (6.6 kb) were isolated from a strain of P. ostreatus. A 1029 bp fragment with high-level ARS activity was cloned from pLPO3 and it contained one ARS consensus sequence (A/T)TTTAT(A/G)TTT(A/T) indispensable for activity and seven dispersed ARS consensus-like (10/11 match) sequences. A discrete bent DNA region was found to lie around 500 bp upstream from the ARS consensus sequence (T-rich strand). Removal of the bent DNA region impaired ARS function. DNA bending was also implicated in the ARS function associated with a 1430 bp fragment containing three consecutive ARS consensus sequences which had been cloned from the L. edodes plasmid pLLE1 (11.0 kb): the three consecutive ARSs responsible for high-level ARS function occurred in, and immediately adjacent to, a bent DNA region. A clear difference exists between the two plasmid-derived ARS fragments with respect to the distance between the bent DNA region and the ARS consensus sequence(s).

A pSC101-par sequence-mediated study on the intracellular state of supercoiling of the pBR322 genome in Escherichia coli DNA topoisomerase I deletion mutant

In Escherichia coli DNA topoisomerase I deletion mutant DM800, transcription of the tetracycline-resistance gene (tet) in the pBR322 genome is thought to create and maintain two domains of positive supercoils ahead, and negative supercoils behind, the transcription complex. To assess the actual intracellular state of twin-supercoiled domains, par sequence (365 bp) of plasmid pSC101, which shows a high affinity for DNA gyrase, was inserted into the EcoRI site upstream, or the AvaI site downstream, of the tet gene on the pBR322 genome. Analysis of the oxolinic acid-induced sites of cleavage by gyrase in DM800 revealed that the pBR322 derivatives are highly preferentially cleaved at the par sequence of the EcoRI site as well as the AvaI site and efficiently linearized when compared with pBR322. Assessment of the state of negative supercoiling of the pBR322 derivatives isolated suggested that the DNA (containing the AvaI site) ahead of the tet transcripts, is not so positively supercoiled and preferential interaction of gyrase with the EcoRI-par sequence does not result in removing negative superhelical turns so effectively as DNA topoisomerase I does on pBR322 DNA in the isogenic wild-type cells.

Isolation and sequence of a developmentally regulated putative novel gene, priA, from the basidiomycete Lentinus edodes

Screening for gene(s) homologous to v-Ha-ras (Harvey rat sarcoma viral ras gene) in the basidiomycete, Lentinus edodes, resulted in the isolation of a novel gene (designated priA), in addition to a ras gene homologue [Hori et al., Gene 105 (1991) 91-96]. The priA gene has a coding capacity of 258 amino acids (aa) interrupted by two short putative introns. The 5'-upstream region of priA contains GGGCGG box, CCAAT box, TATAAA box and CT sequence elements in 5'----3' order. One transcription start point (tsp) was located 10 nucleotides upstream from a TATAAA box and another tsp just in a CT sequence. The deduced PRIA protein (26.7 kDa), rich in Ser (42 residues), Pro (29 residues) and Thr (27 residues), contained different types of putative zinc-binding motifs. It initiated with a hydrophobic aa sequence and terminated with the unique sequence, Cys-Aaa-Aaa-Xaa (where Aaa is aliphatic aa and Xaa is any aa), implying an association with the inner membrane surface via acylation of the Cys residue. The priA gene expression was found to be developmentally regulated with primordia/immature fruiting bodies having much higher levels of priA transcript. Preprimordial mycelia and mature fruiting bodies, however, contain very low levels of priA transcript. The priA gene may play a role during the beginning of fruiting.

Characterization of the promoter region of the basidiomycete Lentinus edodes Le.ras gene

An analysis of the 2.7-kb nucleotide sequence including the 5'-flanking region of the basidiomycete Lentinus edodes Le.ras-encoding gene revealed that the promoter region contains a CAAT box, a CACCC box, two consecutive TATAAA boxes, and a CT-rich sequence element, in that order, from upstream to downstream. One major and two alternative transcriptional initiation sites are located 132 nucleotides and 85 and 90 nucleotides downstream from the downstream TATAAA box, and the major site is positioned just in the CT-rich sequence.

Effects of whole body microwave exposure on the rat brain contents of biogenic amines

The effects of whole body microwave exposure on the central nervous system (CNS) of the rat were investigated. Rats weighing from 250 to 320 g were exposed for 1 h to whole body microwave with a frequency of 2450 MHz at power densities of 5 and 10 mW.cm-2 at an ambient temperature of 21-23 degrees C. The rectal temperatures of the rats were measured just before and after microwave exposure and mono-amines and their metabolites in various discrete brain regions were determined after microwave exposure. Microwave exposure at power densities of 5 and 10 mW.cm-2 increased the mean rectal temperature by 2.3 degrees C and 3.4 degrees C, respectively. The noradrenaline content in the hypothalamus was significantly reduced after microwave exposure at a power density of 10 mW.cm-2. There were no differences in the dopamine (DA) content of any region of the brain between microwave exposed rats and control rats. The dihydroxyphenyl acetic acid (DOPAC) content, the main metabolite of DA, was significantly increased in the pons plus medulla oblongata only at a power density of 10 mW.cm-2. The DA turnover rates, the DOPAC:DA ratio, in the striatum and cerebral cortex were significantly increased only at a power density of 10 mW.cm-2. The serotonin (5-hydroxytryptamine, 5-HT) content in all regions of the brain of microwave exposed rats was not different from that of the control rats. The 5-hydroxyindoleacetic acid (5-HIAA) content in the cerebral cortex of microwave exposed rats was significantly increased at power densities of 5 and 10 mW.cm-2.(ABSTRACT TRUNCATED AT 250 WORDS)

[The effects and pharmacokinetics of rhG-CSF on the treatment of neutropenia in patients with renal failure]

rhG-CSF (recombinant human granulocyte colony stimulating factor) promotes production and release of neutrophil from bone marrow, and it enhances neutrophil function. In this study, the pharmacokinetics, effects on neutrophil and immune functions and efficacy and safety of rhG-CSF were studied in patients with end-stage renal failure (CRF). To 9 patients with CRF; 2 patients on conservative therapy and 7 patients under regular hemodialysis, 50 micrograms/m2 rhG-CSF were administered intravenously under the schedule of single or 2 week consecutive injection. In single injection study, serial changes in plasma rhG-CSF concentration and peripheral blood cell count were examined following the administration. In consecutive injection study, plasma rhG-CSF concentration, anti-rhG-CSF antibody, peripheral blood cell counts, blood chemistry and coagulation factors, and neutrophil and immune functions were examined. As the results, 1) Half life of rhG-CSF, 2.87 +/- 0.65 hr, was about 2 times longer than that in healthy subjects, and it was not affected by hemodialysis treatment. 2) Marked increase in leukocyte and neutrophil counts and mild increase in lymphocyte count were observed during single and consecutive administration of rhG-CSF. There was no significant change in other leukocyte differentiations, RBC, or platelet count. 3) Neutrophil alkaline phosphatase score increased significantly during single and consecutive administration, and other neutrophil function also improved in several patients with impaired neutrophil function. 4) Slight bone pain and increase in serum alkaline phosphatase were observed in about a half of patients during consecutive injection study. Neither antibody nor accumulation of rhG-CSF was noted.(ABSTRACT TRUNCATED AT 250 WORDS)

Gyrase inhibitors increase the content of knotted DNA species of plasmid pBR322 in Escherichia coli

Treatment of Escherichia coli cells harboring pBR322 with the DNA gyrase inhibitors oxolinic acid and coumermycin A1 led to an increase in the content of knotted pBR322 molecules. This phenomenon was attributed to inhibition of gyrase-catalyzed unknotting of the plasmid DNA knotted by transcription.

Cloning, sequence analysis and transcriptional expression of a ras gene of the edible basidiomycete Lentinus edodes

In the edible basidiomycete, Lentinus edodes, the presence of a high level of intracellular cyclic AMP (cAMP) is closely related to the onset of fruiting and/or primordium formation. Since a close relationship between intracellular cAMP levels and expression of ras genes was reported for organisms such as Saccharomyces cerevisiae and Dictyostelium discoideum, we have cloned and sequences a ras gene homologue from L. edodes (Le.), and analyzed its expression during development of the fungus. This gene, named Le.ras, has a coding capacity of 217 amino acids (aa) interrupted by six small introns. The deduced Le.Ras protein exhibited the highest homology to the Schizosaccharomyces pombe RAS protein (219 aa): 86% homology in the N-terminal 80-aa sequence and 74% homology in the next 80 aa. The Le.ras gene was transcribed at similar levels during mycelial development in fruiting-body formation, suggesting no direct correlation of Le.ras expression with intracellular cAMP levels in this organism.