Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.10.3.2 (laccase)
 4,656 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Eight mutants were isolated following mutagen treatment which are deficient in laccase formation. Seven of these had a pleiotropic effect and exhibited defects in growth rate and in mycelial and sexual morphology. 2. By means of tetrad analysis the mutations were assigned to 6 loci. Three mutations were in the incolora locus, the others were non-allelic. Only two of these loci were closely linked. 3. All genes exhibit numerous interactions. These concern the morphological expression of the laccase genes and also the laccase spectra. 4. The mutants could be separated into four classes on the basis of the amount and type of laccase produced. 5. Five of the loci studied appear to be structural genes because mutations alters the physical properties of the laccase protein. The sixth gene has a regulatory role.
Mol Gen Genet 1977 Nov 18
PMID:The phenoloxidases of the ascomycete Podospora anserina. XIII. Action and interaction of genes controlling the formation of laccase. 41 70

Nine volatile hydrocarbons, as well as methyl chloride, carbonyl sulphide and carbon disulphide, have been identified by mass spectrometry as products of Agaricus bisporus in the compost used in comerical mushroom beds. Of these, only ethylene showed a pattern of production that could be correlated with developmental phases of the crop, high levels being produced whenever fruit bodies were rapidly enlarging. In laboratory flask cultures, under controlled conditions, high levels of ethylene occurred whenever young fruit bodies entered the expansion phase. The enhanced rate of ethylene production continued over several days, irrespective of whether fruit bodies were removed. Production occurred within the colonized compost; no ethylene was evolved by the fruit body itself. When the first fruit bodies expanded, either in beds or culture flasks, laccase levels in the compost fell and those of a beta-1,4-glucanase (cellulase) rose. The enzyme switch occurred once only, during maturation of the first fruit bodies, whereas an elevated ethylene production was associated with each occasion when fruit body maturation took place. The low level of laccase and high of cellulase characterized the whole of the reproductive stage of A. bisporus, whereas the phasic periods of high ethylene production distinguished between periods of fruit body maturation and intervening resting periods.
J Gen Microbiol 1975 Nov
PMID:Production of ethylene and other volatiles and changes in cellulase and laccase activities during the life cycle of the cultivated mushroom, Agaricus bisporus. 81 60

We have isolated and characterized a gene coding for the laccase of the lignin-degrading fungus Phlebia radiata. The gene has nine introns and recognizable fungal promoter elements. Sequences homologous to the consensus eukaryotic heat-shock regulatory element can be found in the promoter. RNA hybridization results indicate that this gene is regulated at the transcriptional level. The derived laccase amino acid sequence shows homology to plant ascorbate oxidases, suggesting that the basic structure of the laccase is similar to the three-fold repeated beta-barrel of the ascorbate oxidases. Potential copper ligands and a residue carrying the prosthetic group pyrroloquinoline quinone (PQQ) in the laccase protein can be identified by homology. The intron/exon structure of the laccase gene suggests that this protein could have evolved by exon shuffling.
J Gen Microbiol 1991 Jul
PMID:Isolation and structural analysis of the laccase gene from the lignin-degrading fungus Phlebia radiata. 195 50

The grey-brown pigmentation of Aspergillus nidulans conidiophores depends on the functions of two 'ivory' loci. ivoB codes for a developmental specific phenol oxidase, and mutants accumulate its substrate N-acetyl-6-hydroxytryptophan. ivoA mutants are unable to make this substrate. ygA mutants are also poorly pigmented, and extracts require copper salts to activate both the phenol oxidase and conidial laccase. ivoA and ivoB mutants partially suppress the spore colour phenotype of ygA mutants. Comparisons of morphology, phenol oxidase and substrate accumulation in morphological mutants at the brlA locus suggest that the brlA protein regulates ivoA, ivoB and morphogenetic loci independently. The medA locus, which also affects morphology and pigmentation, may code for a modifier of brlA function. abaA mutants which are blocked at a later stage of development than brlA or medA mutants have low phenol oxidase levels, implying that by this stage of development the activity of the ivoB locus is declining.
J Gen Microbiol 1990 Sep
PMID:The genetics of conidiophore pigmentation in Aspergillus nidulans. 228 2

Asexual spores (conidia) of Aspergillus nidulans contain a dark green pigment which is not present in other cell types. Synthesis of this pigment is catalyzed, in part, by a developmentally controlled p-diphenol oxidase, or laccase, encoded at the gamma A genetic locus (A. J. Clutterbuck, J. Gen. Microbiol. 70:423-435, 1972). We have investigated the mechanisms regulating expression of the gamma A gene of A. nidulans. Vegetative hyphae grown in submerged culture lacked detectable laccase enzyme activity and neither contained nor synthesized immunoprecipitable laccase protein. When such cultures were induced to conidiate by harvesting the cells onto filter papers and aerating them, laccase levels began to increase after 10 to 16 h, reached a peak at 20 to 36 h, and then declined slowly. Immunological assays showed that increases in laccase enzyme activity were (i) proceded by a transient rise in the relative rate of laccase protein synthesis and (ii) closely paralleled by increases in the amount of laccase protein. Addition of cycloheximide to cultures at any time after inducing conidiation inhibited further accumulation of laccase enzyme activity. These data are most consistent with increases in laccase levels being due to regulated, de novo synthesis of laccase protein. Addition of inhibitors of ribonucleic acid synthesis to conidiating cultures also inhibited further accumulation of laccase, suggesting that laccase expression is regulated by alterations in the transcriptional activity of the gamma A locus.
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PMID:Developmental regulation of laccase levels in Aspergillus nidulans. 700 Jul 47

Agaricus bisporus secretes abundant laccase activity into the medium during mycelial growth. SDS-PAGE analysis of extracellular laccase protein, purified from compost extract, showed a predominant band of 65 kDa molecular mass, together with lesser amounts of smaller polypeptides. The main polypeptide was purified electrophoretically. Amino acid sequence analysis of the N-terminal region of the main polypeptide was used to specify the sequence of a 15-residue chemically synthesized peptide (N-terminal peptide). Rabbit antibodies were raised against pure laccase, electrophoretically purified main polypeptide and the synthetic N-terminal peptide. Electrophoretically purified main polypeptide antibody was further purified by affinity chromatography on laccase-CNBr-Sepharose. Western blot analysis showed that the antigenic behaviour of laccase in compost extract, culture filtrate from malt-extract culture, and the purified enzyme from both sources, differed. The patterns of bands revealed are most simply explained by generation of (proteolytically) partially cleaved enzyme molecules in the culture medium, possibly combined with differences in extent of glycosylation. [35S]Methionine incorporation and immunoprecipitation were used to follow laccase synthesis in cultures grown on malt extract. After short-term labelling, a single polypeptide of 68 kDa apparent molecular mass was immunoprecipitated from both mycelial extracts and the culture medium. When poly(A)-containing RNA from malt-extract-grown mycelium was translated in vitro in rabbit reticulocyte lysate, a single polypeptide of about 57 kDa molecular mass was immunoprecipitated, consistent with the previously measured carbohydrate content of 15% for the pure enzyme. After treatment with N-glycanase, the polypeptide showed an increase in mobility during SDS-PAGE consistent with a reduction in molecular mass of about 5 kDa, indicating about equal amounts of N- and O-linked carbohydrate. C-terminal labelling of pure laccase was attempted by transpeptidation with carboxypeptidase Y. Although some minor bands were labelled, the main polypeptide was not, indicating that the C-terminus of the enzyme may be blocked.
J Gen Microbiol 1993 Jan
PMID:The structure of laccase protein and its synthesis by the commercial mushroom Agaricus bisporus. 809 17

A protein synthesis inhibitor, cycloheximide, induces excretion of laccase in Neurospora crassa. The lah-1 mutation results in excretion of a large amount of laccase even in the absence of cycloheximide. Ten mutations were induced that suppress derepressed excretion of laccase in the lah-1 mutant. Of these, seven second-site mutations were found to confer a laccase-noninducible phenotype, and were classified into two different complementation groups. Four mutations define a locus designated lni-1, found to be closely linked to ylo-1 on linkage group VI. The other three mutations were mapped to second locus, designated lni-2, that lies between nic-3 and thi-3 on linkage group VII. The lni-2 locus was shown to encode laccase by RFLP mapping of the DNA fragment encoding laccase and by transformation of the lni-2 mutant with plasmid pBL1 carrying the laccase gene (the locus encoding laccas is hereafter described as lacc). All lacc mutants examined (whether mutagen-induced or inactivated by repeat-induced point mutation) appeared to exhibit no phenotypic deficiency during both asexual and sexual cycles, suggesting that the laccase gene is dispensable in N. crassa. Northern analysis of total cellular RNA from the four lni-1 mutants demonstrated that the lni-1 mutations abolish increased transcription of the laccase gene under inducing conditions. Consequently, the lni-1 locus is inferred to encode a trans-acting positive regulator required for transcriptional activation of the laccase gene in response to cycloheximide. Possible functions of the lah-1 gene are also described.
Mol Gen Genet 1993 Aug
PMID:Isolation and characterization of mutants defective in production of laccase in Neurospora crassa. 810 79

Expression of the laccase gene (lacc) of Neurospora crassa is transcriptionally inducible by the protein synthesis inhibitor cycloheximide. A lni-1 mutation, conferring the laccase non-inducible phenotype, was found to be a cpc-1 allele. Northern blots probed with plasmid pLA1, which carries the lacc gene revealed that the cpc-1 mutation abolishes the induced transcription of the lacc gene, indicating requirement of the cpc-1 gene for transcriptional activation of the lacc gene. In Northern blots probed with plasmid pAB1, which bears arg-2 a gene whose transcription is under the control of CPC1, the level of the arg-2 transcript was shown to increase several-fold in wild-type mycelia but remained low in cpc-1 mycelia, after treatment with cycloheximide. This suggests that inhibition of protein synthesis with cycloheximide, as well as amino acid limitation, elicits the CPC1-mediated cross-pathway control. Characterization of the lacc upstream region using a series of 5'-deletion plasmids led to the identification of a 170 bp DNA region required for the induced lacc expression. Sequence analysis of this DNA region demonstrated that it includes a 9 bp sequence with dyad symmetry, ATGAATCAT, which differs only by a central base pair from ATGA(C/G)TCAT, the recognition sequence characteristic of CPC1 and GCN4 binding sites. Possible mechanisms by which CPC1 mediates transcriptional activation of the lacc gene are discussed.
Mol Gen Genet 1994 Jun 03
PMID:Transcriptional activation of a cycloheximide-inducible gene encoding laccase is mediated by cpc-1, the cross-pathway control gene, in Neurospora crassa. 820 46

A cDNA library was constructed in lambda gt11 using mRNA from 11-d-old mycelium of Agaricus bisporus. Three clones containing laccase sequence were identified using an affinity-purified anti-laccase antibody. From one of these clones, a 333 bp sequence was used to identify further cDNA clones (including one which is close to full length) and a genomic clone. The coding sequences found were of two similar but not identical versions with differences at 36 out of 520 residues of deduced amino acid sequence. The laccase genes each encode a sequence expressed as a 2.3 kb mRNA, specifying a 520 residue polypeptide including a 19 amino acid residue signal peptide that is absent from the N terminus of the mature (extracellular) protein. The coding sequence of lcc1 is interrupted by 14 short introns. The lcc1 and lcc2 genes are not allelic as they do not segregate in uninucleate spores derived from a four-spored basidium. Comparison of the deduced amino acid sequences with that of the other fungal laccases that have been cloned, and with the very similar ascorbate oxidases from higher plants shows that whilst some sequence is absolutely conserved at and around the amino acid residues involved in copper binding, the overall sequence similarities are low.
J Gen Microbiol 1993 Jun
PMID:Identification of two laccase genes in the cultivated mushroom Agaricus bisporus. 836 Jun 14

The genome of the filamentous ascomycete Podospora anserina contains at least four non-adjacent regions that are homologous to the laccase gene of Neurospora crassa. One of these regions contains a gene (lac2) encoding a protein that displays 62% identity with the N. crassa laccase. In shaken cultures, lac2 mRNA is present at low basal levels throughout the growth phase but increases at least 20-fold at the beginning of the autolytic phase and decreases again thereafter. Addition of aromatic xenobiotics (guaiacol, hydroquinone, benzoquinone) to the medium during the growth phase results in a rapid, drastic and temporary increase in the abundance of lac2 mRNA. The promoter region of lac2 contains two sequences which display complete homology with the eukaryotic Xenobiotic Responsive Element and two sequences homologous to the eukaryotic Antioxidant Responsive Element. The identity and function of the laccase encoded by lac2 are discussed.
Mol Gen Genet 1996 Oct 16
PMID:Isolation and characterization of a laccase gene from Podospora anserina. 891 15


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