Molecular and enzymatic characterisation of extra- and intracellular laccases from the acidophilic ascomycete Hortaea acidophila

Tetsch, Larissa; Bend, Jutta; Hölker, Udo

doi:10.1007/s10482-006-9064-z

Cited by 30 publications

(19 citation statements)

References 36 publications

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“…As mentioned before, laccases have been reported both in fungal pigment MCO and ascomycete laccase sensu stricto subgroups, thus all A. niger MCO genes included in the two subfamilies and predicted to be extracellular were selected for their homologous overexpression. The mcoI gene was also selected as it could be targeted to a non-classical secretory pathway and its hypothetical coding product is 49% identical to the laccase I of Hortaea acidophila [33]. In addition mcoE from the ferroxidases/laccases grade was selected, as its coding product is predicted to be an extracellular enzyme and no similar MCO has been characterized so far.…”

Section: Resultsmentioning

confidence: 99%

The Aspergillus niger multicopper oxidase family: analysis and overexpression of laccase-like encoding genes

Tamayo-Ramos

Barends²,

Verhaert³

et al. 2011

Microb Cell Fact

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BackgroundMany filamentous fungal genomes contain complex groups of multicopper oxidase (MCO) coding genes that makes them a good source for new laccases with potential biotechnological interest. A bioinformatics analysis of the Aspergillus niger ATCC 1015 genome resulted in the identification of thirteen MCO genes. Ten of them were cloned and homologously overexpressed.ResultsA bioinformatic analysis of the A. niger ATCC 1015 genome revealed the presence of 13 MCO genes belonging to three different subfamilies on the basis of their phylogenetic relationships: ascomycete laccases, fungal pigment MCOs and fungal ferroxidases. According to in silico amino acid sequence analysis, the putative genes encoding for functional extracellular laccases (mcoA, mcoB, mcoC, mcoD, mcoE, mcoF, mcoG, mcoI, mcoJ and mcoM) were placed under the control of the glaA promoter and overexpressed in A. niger N593. Enzyme activity plate assays with several common laccase substrates showed that all genes are actually expressed and code for active MCOs. Interestingly, expressed enzymes show different substrate specificities. In addition, optimization of fungal pigment MCOs extracellular production was investigated. The performance of the widely used glucoamylase signal sequence (ssGlaA) in McoA secretion was studied. Results obtained suggest that ssGlaA do not yield higher levels of secreted McoA when compared to its native secretion signal. Also, McoB synthesis was investigated using different nitrogen sources in minimal medium liquid cultures. Higher yields of extracellular McoB were achieved with (NH4)2 tartrate.ConclusionsAspergillus niger is a good source of new laccases. The different substrate specificity observed in plate assays makes them interesting to be purified and biochemically compared. The homologous signal sequence of McoA has been shown to be a good choice for its extracellular overexpression. From the nitrogen sources tested (NH4)2 tartrate has been found to be the most appropriate for McoB production in A. niger.

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Section: Resultsmentioning

confidence: 99%

The Aspergillus niger multicopper oxidase family: analysis and overexpression of laccase-like encoding genes

Tamayo-Ramos

Barends²,

Verhaert³

et al. 2011

Microb Cell Fact

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“…2C and Fig. S1) may have resulted in enzymes remaining cell associated (51,52) or in proteins being nonfunctional in laccase activity (28). For the stationary phase of C. aquatica, the obtained pattern of laccase activity and gene expression data (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Induction of fungal laccase gene transcription by lignin-related aromatic compounds has been widely reported (18). Other potential functions of C. aquatica laccase(s) may be related to competition or other interspecies interactions (4,24,31), which could be expected during successions of microbial communities on AQH substrates in aquatic environments (30), and to pigmentation/melanization (17,24,52) as fungal pellets of liquid C. aquatica cultures are turning from grayish into black color with increasing culture age (data not shown), indicating the formation of melanin-like pigments. The highly correlated transcription of the laccase genes lcc1 and lcc5 during the trophophase of C. aquatica (see Table S3 in the supplemental material) and their comparatively high degree of identity among the C. aquatica laccase genes (Table 2) suggest that the corresponding laccase enzymes share an as-yet-unknown function.…”

Section: Discussionmentioning

confidence: 99%

Differential Regulation by Organic Compounds and Heavy Metals of Multiple Laccase Genes in the Aquatic Hyphomycete Clavariopsis aquatica

Solé

Müller

Pecyna

et al. 2012

Appl Environ Microbiol

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ABSTRACTTo advance the understanding of the molecular mechanisms controlling microbial activities involved in carbon cycling and mitigation of environmental pollution in freshwaters, the influence of heavy metals and natural as well as xenobiotic organic compounds on laccase gene expression was quantified using quantitative real-time PCR (qRT-PCR) in an exclusively aquatic fungus (the aquatic hyphomyceteClavariopsis aquatica) for the first time. Five putative laccase genes (lcc1tolcc5) identified inC. aquaticawere differentially expressed in response to the fungal growth stage and potential laccase inducers, with certain genes being upregulated by, e.g., the lignocellulose breakdown product vanillic acid, the endocrine disruptor technical nonylphenol, manganese, and zinc.lcc4is inducible by vanillic acid and most likely encodes an extracellular laccase already excreted during the trophophase of the organism, suggesting a function during fungal substrate colonization. Surprisingly, unlike many laccases of terrestrial fungi, none of theC. aquaticalaccase genes was found to be upregulated by copper. However, copper strongly increases extracellular laccase activity inC. aquatica, possibly due to stabilization of the copper-containing catalytic center of the enzyme. Copper was found to half-saturate laccase activity already at about 1.8 μM, in favor of a fungal adaptation to low copper concentrations of aquatic habitats.

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“…UHH 1-13-18 [68], and in the ascomycete Hortea acidophila [69] implying their potential role in copper induction of laccase expression.…”

Section: Laccase Promoters Sequence Analysismentioning

confidence: 99%

Induction and Transcriptional Regulation of Laccases in Fungi

Piscitelli

Giardina²,

Lettera³

et al. 2011

285

219

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Fungal laccases are phenol oxidases widely studied for their use in several industrial applications, including pulp bleaching in paper industry, dye decolourisation, detoxification of environmental pollutants and revalorization of wastes and wastewaters. The main difficulty in using these enzymes at industrial scale ensues from their production costs. Elucidation of the components and the mechanisms involved in regulation of laccase gene expression is crucial for increasing the productivity of native laccases in fungi. Laccase gene transcription is regulated by metal ions, various aromatic compounds related to lignin or lignin derivatives, nitrogen and carbon sources. In this manuscript, most of the published results on fungal laccase induction, as well as analyses of both the sequences and putative functions of laccase gene promoters are reviewed. Analyses of promoter sequences allow defining a correlation between the observed regulatory effects on laccase gene transcription and the presence of specific responsive elements, and postulating, in some cases, a mechanism for their functioning. Only few reports have investigated the molecular mechanisms underlying laccase regulation by different stimuli. The reported analyses suggest the existence of a complex picture of laccase regulation phenomena acting through a variety of cis acting elements. However, the general mechanisms for laccase transcriptional regulation are far from being unravelled yet.

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Molecular and enzymatic characterisation of extra- and intracellular laccases from the acidophilic ascomycete Hortaea acidophila

Cited by 30 publications

References 36 publications

The Aspergillus niger multicopper oxidase family: analysis and overexpression of laccase-like encoding genes

The Aspergillus niger multicopper oxidase family: analysis and overexpression of laccase-like encoding genes

Differential Regulation by Organic Compounds and Heavy Metals of Multiple Laccase Genes in the Aquatic Hyphomycete Clavariopsis aquatica

Induction and Transcriptional Regulation of Laccases in Fungi

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