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Cloning and characterization of a G protein alpha-subunit-encoding gene from the basidiomycete, Coprinus congregatus.

Complementary DNA (cDNA) clones encoding two G protein alpha-subunit proteins (CGP alpha 1 and CGP alpha 2) were isolated from a Coprinus congregatus (Cc) hyphal tip cell (HTC) library using PCR-generated biotinylated G protein probes. Sequence analysis of the Cc cgp alpha 1 gene indicates that the gene contains an open reading frame (ORF) that translates into a putative 353-amino-acid (aa) product. The predicted CGP alpha 1 protein exhibits similarity to all known G protein alpha-subunits (it has all of the consensus regions for a GTP-binding protein), especially the mammalian retinal G protein, transducin. The CGP alpha 1 aa sequence is 50% identical overall to the transducin subfamily, cgp alpha 1 shares the same aa size grouping as transducin alpha-subunits and, unlike many other G proteins, both CGP alpha 1 and transducin seem to possess a cholera toxin (CTX)- and pertussis toxin (PTX)-sensitive site. Preliminary reverse transcription PCR (RT-PCR) analysis of cgp alpha 1 and cgp alpha 2 mRNA expression revealed that, unlike cgp alpha 2 which seems to be constitutively expressed, cgp alpha 1 is expressed only in HTC that are competent in responding to light. Thus, the cgp alpha 1 product, CGP alpha 1, is a likely candidate for regulating the blue light-induced signal transduction photomorphogenesis system found in Cc.

Amino Acid Sequence↗

Heterodimerization between two classes of homeodomain proteins in the mushroom Coprinus cinereus brings together potential DNA-binding and activation domains.

The A mating type-genes of the mushroom, Coprinus cinereus, encode two classes of homeodomain-containing proteins distinguished as HD1 and HD2 on the basis of conserved, but distinctly different motifs. Compatible mating partners bring together versions of the proteins that can heterodimerize, thereby generating an active transcription factor complex that commits mated cells to sexual development. We have previously described a rare mutation in which an HD2::HD1 gene fusion generates a 'fused dimer' lacking much of HD1 including the homeodomain yet capable of constitutively promoting development [Kües et al., EMBO J. 13 (1994b) 4054-4059]. Here, we exploit this mutation to help identify contributions made by each protein class to normal heterodimer function. We show that the HD2 homeodomain is essential; deletion within the HD1 homeodomain can be tolerated in a normal heterodimer, as well as in the mutant fusion protein, but not substitution of a critical amino acid. We define, by deletion analysis, an essential C-terminal region of the HD1 and demonstrate its potential activation function by the ability to activate transcription in yeast when fused to the GAL4 DNA-binding domain. We also identify a potential role in transcriptional repression for the predicted C-terminal helix of HD1 proteins.

Amino Acid Sequence↗

Structural elucidation of a neutral fucogalactan from the mycelium of Coprinus comatus.

A water-soluble fucogalactan (CMP3), with a molecular mass of 1.03 x 10(4) Da as determined by high-performance size-exclusion chromatography (HPSEC), was obtained from the crude intracellular polysaccharide of Coprinus comatus mycelium. Its chemical structure was characterized by sugar and methylation analysis along with 1H and 13C NMR spectroscopy, including NOESY and HMBC experiments for linkage and sequence analysis. The polysaccharide is composed of a pentasaccharide repeating unit with the following structure: [structure:see text].

Carbohydrate Sequence↗

Identification of a novel bifunctional delta12/delta15 fatty acid desaturase from a basidiomycete, Coprinus cinereus TD#822-2.

A new gene encoding a delta12 fatty acid desaturase-related protein was cloned from a multicellular basidiomycete Coprinus cinereus TD#822-2. The 1326 bp full-length gene, designated as Cop-odeA, codes for a putative protein of 442 amino acids with a MW of 49224. The Cop-odeA yeast transformant accumulated four new fatty acids identified as 9,12-hexadecadienoic acid, 9,12,15-hexadecatrienoic acid, linoleic acid, and alpha-linolenic acid, which comprised 8.8%, 1.0%, 29.0%, and 0.6% of the total fatty acids, respectively. The Cop-odeA protein was confirmed to be a novel bifunctional fatty acid desaturase with both high delta12 desaturase activity and unusual delta15 desaturase activity.

Cloning, Molecular↗

Expression of flap endonuclease-1 during meiosis in a basidiomycete, Coprinus cinereus.

In the basidiomycete Coprinus cinereus (C. cinereus), which shows a highly synchronous meiotic cell cycle, the meiotic prophase I cells demonstrate flap endonuclease-1 activity. To investigate its role during meiosis, we isolated a C. cinereus cDNA homolog of flap endonuclease-1 (CcFEN-1), 1377bp in length with the open reading frame (ORF) encoding a predicted molecular mass of 51 kDa. At amino-acid residues Glu276-Pro345, a specific inserted sequence composed of 70 amino acids rich in polar forms was found to exist, without sequence identity to other eukaryotic FEN-1 or the polar amino acid rich sequences found in C. cinereus PCNA and C. cinereus DNA ligase IV, although the lengths and percentages of polar amino acids were similar. Northern hybridization analysis indicated CcFEN-1 to be expressed not only in the pre-meiotic S phase but also in meiotic prophase I. The roles of CcFEN-1 during meiosis are discussed.

Amino Acid Sequence↗

The eln3 gene involved in fruiting body morphogenesis of Coprinus cinereus encodes a putative membrane protein with a general glycosyltransferase domain.

We identified and characterized elongationless3 (eln3-1), a restriction enzyme-mediated integration (REMI) mutation affecting fruiting body morphogenesis in Coprinus cinereus. The mutant produces an aberrant fruiting body in which the stipe hardly elongates during fruiting body maturation. In the wild type, cylindrical stipe cells, elongation growth of which is responsible for stipe elongation, make side-by-side contact with one another and run parallel to the stipe axis, whereas in the mutant, the organization of the stipe tissue is disturbed and much space is produced between stipe cells. This disorganization of the stipe tissue, together with reduced elongation of the stipe cells, causes the mutant stipe short and bulgy. After a plasmid rescue, the eln3 gene was identified as a DNA fragment that complements the eln3-1 mutation. The eln3 ORF is predicted to encode a protein of 927 amino acids with a general glycosyltransferase domain and to be located in the plasma membrane. Transcription of the eln3 gene is specifically activated in rapidly elongating stipes. Possible involvement of the putative Eln3 enzyme in cell-to-cell connection is discussed.

Alleles↗

Efficient GFP expression in the mushrooms Agaricus bisporus and Coprinus cinereus requires introns.

We have developed a "Molecular Toolkit" comprising interchangeable promoters and marker genes to facilitate transformation of homobasidiomycete mushrooms. We describe the evaluation of a range of promoters in the homobasidiomycetes Agaricus bisporus and Coprinus cinereus using green fluorescent protein (GFP) as a reporter gene; the C. cinereus trp1 promoter and A. bisporus trp2 and gpdII promoters proving successful in driving expression in C. cinereus, with the gpdII promoter also functioning in A. bisporus. Our investigations demonstrate that a prerequisite for GFP expression in C. cinereus and A. bisporus is the presence of an intron. This is the first reported expression of GFP in either C. cinereus or A. bisporus.

Agaricus↗

Roles of distal arginine in activity and stability of Coprinus cinereus peroxidase elucidated by kinetic and NMR analysis of the Arg51Gln, -Asn, -Leu, and -Lys mutants.

In heme peroxidases, a distal His residue plays an essential role in the initial two electron oxidation of resting state enzyme to compound I by hydrogen peroxide. A distal Arg residue assists in this process. The contributions of the charge, H-bonding capacity, size, and mobility of this Arg residue to Coprinus cinereus peroxidase (CIP) reactivity and stability have been examined by substituting Arg51 with Gln (retains H-bond donor at N epsilon position), Asn (small size, H-bond donor and acceptor), Leu (similar to Asn, but hydrophobic), and Lys (charge and H-bond donor, but at N zeta position). UV-visible spectroscopy was used to monitor pH-linked heme changes, compound I formation and reduction, fluoride binding, and thermostability. (1)H NMR spectroscopy enabled heme pocket differences in both resting and cyanide-ligated states of the enzymes to be evaluated and compared with wild-type CIP. We found that the H-bonding capacity of distal Arg is key to fast compound I formation and ligand binding to heme, whereas charge is important for lowering the pK(a) of distal His and for the binding and stabilisation of anionic ligands at heme iron. The properties of the distal Arg residue in CIP, cytochrome c peroxidase (CCP) and horseradish peroxidase (HRP) differ significantly in their pH induced transitions and dynamics.

Amino Acid Substitution↗

Hypoglycemic activity of fermented mushroom of Coprinus comatus rich in vanadium.

The hypoglycemic activity of fermented mushroom of Coprinus comatus rich in vanadium (CCRV) was studied in this paper. Alloxan and adrenalin induced hyperglycemic mice were used in the study. The blood glucose and the HbA1c of the mice were analyzed, respectively. At the same time, the sugar tolerance of the normal mice was also determined. After the mice were administered (ig) with CCRV, the blood glucose and the HbA1c of alloxan-induced hyperglycemic mice decreased (p < 0.05, p < 0.01), ascension of blood glucose induced by adrenalin was inhibited (p < 0.01) and the sugar tolerance of the normal mice was improved. Also, the body weight of the alloxan-induced hyperglycemic mice was increased gradually. In the fermented mushroom of C. comatus, vanadium at lower doses in combination with C. comatus, induced significant decreases of the blood glucose and HbA1c levels in hyperglycemic mice.

Alloxan↗

Inactivation of Coprinus cinereus peroxidase by 4-chloroaniline during turnover: comparison with horseradish peroxidase and bovine lactoperoxidase.

The peroxidase from Coprinus cinereus (CPX) catalyzed oxidative oligomerization of 4-chloroaniline (4-CA) forming several products: N-(4-chlorophenyl)-benzoquinone monoamine (dimer D), 4,4'-dichloroazobenzene (dimer E); 2-(4-chloroanilino)-N-(4-chlorophenyl)-benzoquinone (trimer F); 2-amino-5-chlorobenzoquinone-di-4-chloroanil (trimer G); 2-(4-chloroanilino)-5-hydroxybenzoquinone-di-4-chloroanil (tetramer H) and 2-amino-5-(-4-chlroanilino)-benzoquinone-di-4-chloroanil (tetramer 1). In the presence of 4-CA and H2O2, CPX was irreversibly inactivated within 10 min. Inactivation of CPX in the presence of H2O2 was a time-dependent, first-order process when the concentration of 4-CA was varied between 0 and 2.5 mM. The apparent dissociation constant (Ki) for CPX and 4-CA was 0.71 mM. The pseudo-first order rate constant for inactivation (k(inact)), was 1.15 x 10(-2) s(-1). Covalent incorporation of 20 mole 14C-4-CA per mole of inactivated CPX was observed. The partition ratio was about 2200 when either 4-CA or H2O2 was used as the limiting substrate. These results show that 4-CA is a metabolically activated inactivator (i.e. a suicide substrate). Unmodified heme and hydroxymethyl heme were isolated from native, 4-CA-inactivated and H2O2-incubated CPX. Inactivation resulted in significant losses in both heme contents. Analysis of tryptic peptides from 4-CA-inactivated CPX by MALDI-TOF/ MS and UV-VIS spectrophotometry suggested that trimer G and tetramer H were the major 4-CA derivatives that were covalently bound, including to a peptide (MGDAGF-SPDEVVDLLAAHSLASQEGLNSAIFR) containing the heme binding site. These studies show that heme destruction and covalent modification of the polypeptide chain are both important for the inactivation of CPX. These results were compared with similar studies on 4-CA-inactivated horseradish peroxidase (HRP) and bovine lactoperoxidase (LPO) during the oxidation of 4-CA.

Amino Acid Sequence↗

Coprinus cinereus DNA ligase I during meiotic development.

DNA ligase I is thought to be essential for DNA replication, repair and recombination, at least in the mitotic cell cycle, but whether this is also the case during the meiotic cell cycle is still obscure. To investigate the role of DNA ligase I during the meiotic cell cycle, we cloned the Coprinus cinereus DNA ligase I cDNA (CcLIG1). Northern blotting analysis indicated that CcLIG1 is expressed not only in the premeiotic S-phase but also during the meiotic cell cycle itself. Especially, intense signals were observed in the leptotene and zygotene stages. Western blotting analysis indicated that CcLIG1 is expressed through the meiotic cell cycle and immunofluorescence also showed CcLIG1 protein staining in meiotic cells. Interestingly, the patterns was similar to that for the C. cinereus proliferating cell nuclear antigen gene (CcPCNA) and immunoprecipitation analysis suggested that CcPCNA binds to CcLIG1 in crude extracts of meiotic prophase I tissues. Based on these observations, relationships and roles during the meiotic cell cycle are discussed.

Amino Acid Sequence↗

Kinetic evidence for surface residues influencing the active site of Coprinus cinereus peroxidase: analysis of the pH dependence of G154E, P90H and P90H-G154E substrate entrance mutants.

Three mutants of Coprinus cinereus peroxidase (CIP) were made to mimic the substrate entrance histidine 82-glutamic acid 146 pair of the substrate channel in lignin peroxidase (LIP). Compound I formation of LIP has a low pH optimum around pH 3, while optimal formation of CIP compound I is obtained at pH 6-11. The mutants were glycine 154-->glutamic acid (G154E), proline 90-->histidine (P90H) and the double mutant P90H-G154E. All three showed kinetics of compound I formation similar to that of wt CIP between pH 3 and 9. However, the stability of compound I was strongly affected by these mutations. In wt CIP compound I is stable for approximately 30 min, while compound I of the mutants were stable for 5 s or less. The P90H and P90H-G154E mutants showed pK(a) values for the alkaline transition at least one pH unit lower than for wt CIP and the G154E mutant. We suggest that the changed electrostatic field results in destabilisation of the oxidised heme in compound I and II and that the P90H residue increases the electrostatic potential in the distal cavity thereby decreasing the pK(a) for the alkaline transition.

Binding Sites↗

Nucleotide sequences of genes for ribosomal protein L41 and tRNAThr(AGU) from Coprinus cinereus.

The nucleotide sequences of genes for the homolog in Coprinus cinereus of the eukaryotic ribosomal protein L41 and for tRNAThr(AGU) are reported. The gene for tRNAThr(AGU) was located upstream of the gene for the L41 ribosomal protein, and these genes were adjacent to each other but in opposite orientations. The deduced amino acid sequence of ribosomal protein L41 exhibited strong homology to those of L41 proteins of several yeasts. The 56th amino acid of the deduced protein was proline, as it is in the L41 protein of a cycloheximide-sensitive strain of yeast. The putative secondary structure of the tRNA gene resembled the characteristic cloverleaf structure of tRNAs. Elements resembling an A-box and a B-box were found in the gene for tRNAThr(AGU). These boxes are known as internal promoter elements in genes for eukaryotic tRNAs.

Amino Acid Sequence↗

Adapting protein solubility by glycosylation. N-glycosylation mutants of Coprinus cinereus peroxidase in salt and organic solutions.

Protein solubility is a fundamental parameter in biology and biotechnology. In the present study we have constructed and analyzed five mutants of Coprinus cinereus peroxidase (CIP) with 0, 1, 2, 4 and 6 N-glycosylation sites. All mutants contain Man(x)(GlcNAc)(2) glycans. The peroxidase activity was the same for wild-type CIP and all the glycosylation mutants when measured with the large substrate 2,2'-azino-bis(-3-ethylbenzthiazoline-6-sulfonic acid). The solubility of the five CIP mutants showed a linear dependence on the number of carbohydrate residues attached to the protein in buffered solution of both ammonium sulfate (AMS) and acetone, increasing in AMS and decreasing in acetone. Moreover, the change in free energy of solvation appears to be a constant, though with opposite signs in these solvents, giving DeltaDeltaG degrees (sol)=-0.32+/-0.05 kJ/mol per carbohydrate residue in 2.0 M AMS, a value previously obtained comparing ordinary and deglycosylated horseradish peroxidase, and 0. 37+/-0.10 kJ/mol in 60 v/v% acetone.

Aspergillus oryzae↗

Enzymatic removal of phenols from aqueous solutions by Coprinus cinereus peroxidase and hydrogen peroxide.

The fungal enzyme Coprinus cinereus peroxidase (CIP) can be used for the removal of toxic phenols from water. After treating aqueous solutions of phenols with CIP and H2O2 the phenols polymerized and precipitated. The decrease in phenol concentration was investigated for 10 different phenols. At neutral pH, the investigated phenols were in general removed with high efficiency.

Coprinus↗

Production of protein by fungi from agricultural wastes. VI. Quality of the protein formed in Rhizoctonia melongina, Pleurotus ostreatus, and Coprinus aratus.

The amino acid content of the three fungi, viz., Rhizoctonia melongina, Pleurotus ostreatus, and Coprinus aratus, grown in liquid media (JAUHRI and SEN 1978d) containing agricultural wastes (sugarcane bagasse for the former two and wheat straw for the latter), were analysed qualitatively. Amino acid fraction of the three fungi, determined through paper chromatography, contained all the 8 essential amino acids in addition to 9 odd amino acids, except in the case of Rhizoctonia melongina in which the essential amino acid lysine was lacking. The possibilities for mass production and the use of these three fungi in dietetics are further discussed in this paper.

Agaricales↗

Distribution of mechanical stress is not involved in regulating stipe gravitropism in Coprinus cinereus.

Removal of large segments of the apical part of the stipe of Coprinus cinereus (extending to about half its length) affected neither the ability of the stipe to show gravitropic bending nor its ability to compensate the curvature so induced and adjust to the vertical. However, gravitropic reaction time was directly proportional to the amount of stipe removed. Application of lateral loads of up to 20 g had no adverse effects on adjustment of the stipe to the vertical and continued vertical growth. It is concluded that sensing the distribution of extracellular mass and/or mechanical stress is unlikely to be a component of the control of gravitropic bending in C. cinereus stipes.

Coprinus↗

White-cap mutants and meiotic apoptosis in the basidiomycete Coprinus cinereus.

Among many white-cap mutants of Coprinus cinereus, four distinct classes have been identified cytologically. Mutants of one class progress through meiosis normally but fail to sporulate; the defect is post-meiotic and it triggers apoptosis in the tetrad stage. Mutants of the other three classes have defects in meiotic prophase and these are: (1) those that assemble synaptonemal complexes (SCs) normally; (2) those that assemble axial elements (AEs) but not SCs; and (3) those that assemble neither AEs nor SCs even though the chromosomes are condensed and also paired. All three meiotic mutant classes arrest at meiotic metaphase I and the arrest triggers meiosis-specific apoptosis showing characteristic chromatin condensation, DNA fragmentation as shown by the TUNEL assay, cytoplasmic shrinkage, and finally total DNA degradation. Apoptosis is very cell-type specific; it occurs only in the basidia while the neighboring somatic cells are perfectly healthy and the mushroom continues to develop and mature with very few basidiospores produced. The meiotic apoptosis in C. cinereus is under strict cell cycle control rather than at any time after defect; apoptosis is triggered only after entry to meiotic metaphase. It is intriguing to note that C. cinereus has two checkpoints for arrest and entry to apoptosis: one is meiotic at the metaphase I spindle checkpoint regardless of the time of defects, and one is post-meiotic at the tetrad stage. This is in striking contrast to multiple checkpoint arrests and entries to meiotic apoptosis found in the mouse.

Apoptosis↗