151
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Isolation of five laccase gene sequences from the white-rot fungus Trametes sanguinea by PCR, and cloning, characterization and expression of the laccase cDNA in yeasts. J Biosci Bioeng 2001. [DOI: 10.1016/s1389-1723(01)80242-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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152
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Abstract
Thermophilic fungi are a small assemblage in mycota that have a minimum temperature of growth at or above 20 degrees C and a maximum temperature of growth extending up to 60 to 62 degrees C. As the only representatives of eukaryotic organisms that can grow at temperatures above 45 degrees C, the thermophilic fungi are valuable experimental systems for investigations of mechanisms that allow growth at moderately high temperature yet limit their growth beyond 60 to 62 degrees C. Although widespread in terrestrial habitats, they have remained underexplored compared to thermophilic species of eubacteria and archaea. However, thermophilic fungi are potential sources of enzymes with scientific and commercial interests. This review, for the first time, compiles information on the physiology and enzymes of thermophilic fungi. Thermophilic fungi can be grown in minimal media with metabolic rates and growth yields comparable to those of mesophilic fungi. Studies of their growth kinetics, respiration, mixed-substrate utilization, nutrient uptake, and protein breakdown rate have provided some basic information not only on thermophilic fungi but also on filamentous fungi in general. Some species have the ability to grow at ambient temperatures if cultures are initiated with germinated spores or mycelial inoculum or if a nutritionally rich medium is used. Thermophilic fungi have a powerful ability to degrade polysaccharide constituents of biomass. The properties of their enzymes show differences not only among species but also among strains of the same species. Their extracellular enzymes display temperature optima for activity that are close to or above the optimum temperature for the growth of organism and, in general, are more heat stable than those of the mesophilic fungi. Some extracellular enzymes from thermophilic fungi are being produced commercially, and a few others have commercial prospects. Genes of thermophilic fungi encoding lipase, protease, xylanase, and cellulase have been cloned and overexpressed in heterologous fungi, and pure crystalline proteins have been obtained for elucidation of the mechanisms of their intrinsic thermostability and catalysis. By contrast, the thermal stability of the few intracellular enzymes that have been purified is comparable to or, in some cases, lower than that of enzymes from the mesophilic fungi. Although rigorous data are lacking, it appears that eukaryotic thermophily involves several mechanisms of stabilization of enzymes or optimization of their activity, with different mechanisms operating for different enzymes.
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Affiliation(s)
- R Maheshwari
- Department of Biochemistry, Indian Institute of Science, Bangalore 560 012, India.
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153
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Blinkovsky AM, Byun T, Brown KM, Golightly EJ, Klotz AV. A non-specific aminopeptidase from Aspergillus. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1480:171-81. [PMID: 10899618 DOI: 10.1016/s0167-4838(00)00064-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A fermentation broth supernatant of the Aspergillus oryzae strain ATCC20386 contains aminopeptidase activity that releases a wide variety of amino acids from natural peptides. The supernatant was fractionated by anion exchange chromatography. Based on the primary amino acid sequence data obtained from proteins in certain fractions, polymerase chain reaction (PCR) primers were made and a PCR product was generated. This PCR product was used to screen an A. oryzae cDNA library from which the full length gene was then obtained. Fusarium venenatum and A. oryzae were used as hosts for gene expression. Transformed strains of both F. venenatum and A. oryzae over-expressed an active aminopeptidase (E.C. 3.4.11), named aminopeptidase II. The recombinant enzyme from both fungal hosts appeared as smears on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. After deglycosylation of the N-linked sugars, both samples were a sharp band at approximately 56 kDa and had identical N-terminal amino acid sequences. Aminopeptidase II is a metalloenzyme with, presumably, Zn in the active site. Using various natural peptides and para-nitroanilides (pNAs) of amino acids as substrates, the aminopeptidase was found to be non-specific. Only X-Pro bonds demonstrated resistance to hydrolysis catalyzed by this aminopeptidase. The optimal enzyme activity was observed at pH 9.5 and 55 degrees C. Among amino acid pNAs, Leu-pNA appears to have the highest value of bimolecular constant of 40 min(-1) mM(-1) (k(cat) = 230 min(-1); K(m) = 5.8 mM) at pH 7.5 and 21 degrees C. Among Xaa-Ala-Pro-Tyr-Lys-amide pentapeptides, the velocity of catalytic hydrolysis at pH 7.5 and 21 degrees C was in a decreasing order: Pro, Ala, Leu, Gly and Glu.
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Affiliation(s)
- A M Blinkovsky
- Novo Nordisk Biotech Inc., 1445 Drew Avenue, Davis, CA 95616, USA.
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154
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Vasil’chenko LG, Koroleva OV, Stepanova EV, Landesman EO, Rabinovich ML. Isolation and characterization of a micromycete, a producer of neutral catechol oxidases, from tropical soils with elevated dioxine content. APPL BIOCHEM MICRO+ 2000. [DOI: 10.1007/bf02738042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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155
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Xu F, Kulys JJ, Duke K, Li K, Krikstopaitis K, Deussen HJ, Abbate E, Galinyte V, Schneider P. Redox chemistry in laccase-catalyzed oxidation of N-hydroxy compounds. Appl Environ Microbiol 2000; 66:2052-6. [PMID: 10788380 PMCID: PMC101453 DOI: 10.1128/aem.66.5.2052-2056.2000] [Citation(s) in RCA: 193] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/1999] [Accepted: 02/08/2000] [Indexed: 11/20/2022] Open
Abstract
1-Hydroxybenzotriazole, violuric acid, and N-hydroxyacetanilide are three N-OH compounds capable of mediating a range of laccase-catalyzed biotransformations, such as paper pulp delignification and degradation of polycyclic hydrocarbons. The mechanism of their enzymatic oxidation was studied with seven fungal laccases. The oxidation had a bell-shaped pH-activity profile with an optimal pH ranging from 4 to 7. The oxidation rate was found to be dependent on the redox potential difference between the N-OH substrate and laccase. A laccase with a higher redox potential or an N-OH compound with a lower redox potential tended to have a higher oxidation rate. Similar to the enzymatic oxidation of phenols, phenoxazines, phenothiazines, and other redox-active compounds, an "outer-sphere" type of single-electron transfer from the substrate to laccase and proton release are speculated to be involved in the rate-limiting step for N-OH oxidation.
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Affiliation(s)
- F Xu
- Novo Nordisk Biotech, Davis, California 95616, USA.
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156
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Gorbatova ON, Stepanova EV, Koroleva OV. Studies of some biochemical and physicochemical properties of an inducible form of extracellular laccase from the basidiomyceteCoriolus hirsutus. APPL BIOCHEM MICRO+ 2000. [DOI: 10.1007/bf02742571] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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157
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Fuglsang CC, Berka RM, Wahleithner JA, Kauppinen S, Shuster JR, Rasmussen G, Halkier T, Dalboge H, Henrissat B. Biochemical analysis of recombinant fungal mutanases. A new family of alpha1,3-glucanases with novel carbohydrate-binding domains. J Biol Chem 2000; 275:2009-18. [PMID: 10636904 DOI: 10.1074/jbc.275.3.2009] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nucleotide sequence analysis shows that Trichoderma harzianum and Penicillium purpurogenum alpha1,3-glucanases (mutanases) have homologous primary structures (53% amino acid sequence identity), and are composed of two distinct domains: a NH(2)-terminal catalytic domain and a putative COOH-terminal polysaccharide-binding domain separated by a O-glycosylated Pro-Ser-Thr-rich linker peptide. Each mutanase was expressed in Aspergillus oryzae host under the transcriptional control of a strong alpha-amylase gene promoter. The purified recombinant mutanases show a pH optimum in the range from pH 3.5 to 4.5 and a temperature optimum around 50-55 degrees C at pH 5.5. Also, they exhibit strong binding to insoluble mutan with K(D) around 0.11 and 0.13 microM at pH 7 for the P. purpurogenum and T. harzianum mutanases, respectively. Partial hydrolysis showed that the COOH-terminal domain of the T. harzianum mutanase binds to mutan. The catalytic domains and the binding domains were assigned to a new family of glycoside hydrolases and to a new family of carbohydrate-binding domains, respectively.
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158
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Yaver DS, Overjero MD, Xu F, Nelson BA, Brown KM, Halkier T, Bernauer S, Brown SH, Kauppinen S. Molecular characterization of laccase genes from the basidiomycete Coprinus cinereus and heterologous expression of the laccase lcc1. Appl Environ Microbiol 1999; 65:4943-8. [PMID: 10543807 PMCID: PMC91665 DOI: 10.1128/aem.65.11.4943-4948.1999] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A laccase from Coprinus cinereus is active at alkaline pH, an essential property for some potential applications. We cloned and sequenced three laccase genes (lcc1, lcc2, and lcc3) from the ink cap basidiomycete C. cinereus. The lcc1 gene contained 7 introns, while both lcc2 and lcc3 contained 13 introns. The predicted mature proteins (Lcc1 to Lcc3) are 58 to 80% identical at the amino acid level. The predicted Lcc1 contains a 23-amino-acid C-terminal extension rich in arginine and lysine, suggesting that C-terminal processing may occur during its biosynthesis. We expressed the Lcc1 protein in Aspergillus oryzae and purified it. The Lcc1 protein as expressed in A. oryzae has an apparent molecular mass of 66 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and absorption maxima at 278 and 614 nm. Based on the N-terminal protein sequence of the laccase, a 4-residue propeptide was processed during the maturation of the enzyme. The dioxygen specificity of the laccase showed an apparent K(m) of 21 +/- 2 microM and a catalytic constant of 200 +/- 10 min(-1) for O(2) with 2, 2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) as the reducing substrate at pH 5.5. Lcc1 from A. oryzae may be useful in industrial applications. This is the first report of a basidiomycete laccase whose biosynthesis involves both N-terminal and C-terminal processing.
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Affiliation(s)
- D S Yaver
- Novo Nordisk Biotech, Davis, California 95616, USA.
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159
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Zhao J, Kwan HS. Characterization, molecular cloning, and differential expression analysis of laccase genes from the edible mushroom Lentinula edodes. Appl Environ Microbiol 1999; 65:4908-13. [PMID: 10543802 PMCID: PMC91660 DOI: 10.1128/aem.65.11.4908-4913.1999] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The effect of different substrates and various developmental stages (mycelium growth, primordium appearance, and fruiting-body formation) on laccase production in the edible mushroom Lentinula edodes was studied. The cap of the mature mushroom showed the highest laccase activity, and laccase activity was not stimulated by some well-known laccase inducers or sawdust. For our molecular studies, two genomic DNA sequences, representing allelic variants of the L. edodes lac1 gene, were isolated, and DNA sequence analysis demonstrated that lac1 encodes a putative polypeptide of 526 amino acids which is interrupted by 13 introns. The two allelic genes differ at 95 nucleotides, which results in seven amino acid differences in the encoded protein. The copper-binding domains found in other laccase enzymes are conserved in the L. edodes Lac1 proteins. A fragment of a second laccase gene (lac2) was also isolated, and competitive PCR showed that expression of lac1 and lac2 genes was different under various conditions. Our results suggest that laccases may play a role in the morphogenesis of the mushroom. To our knowledge, this is the first report on the cloning of genes involved in lignocellulose degradation in this economically important edible fungus.
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Affiliation(s)
- J Zhao
- Department of Biology, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong SAR, China
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160
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Palmer AE, Randall DW, Xu F, Solomon EI. Spectroscopic Studies and Electronic Structure Description of the High Potential Type 1 Copper Site in Fungal Laccase: Insight into the Effect of the Axial Ligand. J Am Chem Soc 1999. [DOI: 10.1021/ja991087v] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Amy E. Palmer
- Contribution from the Department of Chemistry, Stanford University, Stanford, California 94306, and Novo Nordisk Biotechnology, Davis, California 95616
| | - David W. Randall
- Contribution from the Department of Chemistry, Stanford University, Stanford, California 94306, and Novo Nordisk Biotechnology, Davis, California 95616
| | - Feng Xu
- Contribution from the Department of Chemistry, Stanford University, Stanford, California 94306, and Novo Nordisk Biotechnology, Davis, California 95616
| | - Edward I. Solomon
- Contribution from the Department of Chemistry, Stanford University, Stanford, California 94306, and Novo Nordisk Biotechnology, Davis, California 95616
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161
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Li K, Xu F, Eriksson KE. Comparison of fungal laccases and redox mediators in oxidation of a nonphenolic lignin model compound. Appl Environ Microbiol 1999; 65:2654-60. [PMID: 10347057 PMCID: PMC91392 DOI: 10.1128/aem.65.6.2654-2660.1999] [Citation(s) in RCA: 253] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Several fungal laccases have been compared for the oxidation of a nonphenolic lignin dimer, 1-(3, 4-dimethoxyphenyl)-2-(2-methoxyphenoxy)propan-1,3-diol (I), and a phenolic lignin model compound, phenol red, in the presence of the redox mediators 1-hydroxybenzotriazole (1-HBT) or violuric acid. The oxidation rates of dimer I by the laccases were in the following order: Trametes villosa laccase (TvL) > Pycnoporus cinnabarinus laccase (PcL) > Botrytis cinerea laccase (BcL) > Myceliophthora thermophila laccase (MtL) in the presence of either 1-HBT or violuric acid. The order is the same if the laccases are used at the same molar concentration or added to the same activity (with ABTS [2, 2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)] as a substrate). During the oxidation of dimer I, both 1-HBT and violuric acid were to some extent consumed. Their consumption rates also follow the above order of laccases, i.e., TvL > PcL > BcL > MtL. Violuric acid allowed TvL and PcL to oxidize dimer I much faster than 1-HBT, while BcL and violuric acid oxidized dimer I more slowly than BcL and 1-HBT. The oxidation rate of dimer I is dependent upon both kcat and the stability of the laccase. Both 1-HBT and violuric acid inactivated the laccases, violuric acid to a greater extent than 1-HBT. The presence of dimer I or phenol red in the reaction mixture slowed down this inactivation. The inactivation is mainly due to the reaction of the redox mediator free radical with the laccases. We did not find any relationship between the carbohydrate content of the laccases and their inactivation. When the redox potential of the laccases is in the range of 750 to 800 mV, i.e., above that of the redox mediator, it does not affect kcat and the oxidation rate of dimer I.
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Affiliation(s)
- K Li
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602-7229, USA
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162
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Sabuquillo P, Reina J, Fernandez-Lorente G, Guisan JM, Fernandez-Lafuente R. 'Interfacial affinity chromatography' of lipases: separation of different fractions by selective adsorption on supports activated with hydrophobic groups. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1388:337-48. [PMID: 9858762 DOI: 10.1016/s0167-4838(98)00183-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Lipases contained in commercial samples of lipase extracts from Rhizopus niveus (RNL) and Candida rugosa (CRL) have been selectively adsorbed on hydrophobic supports at very low ionic strength. Under these conditions, adsorption of other proteins (including some esterases) is almost negligible. More interestingly, these lipases could be separated in several active fractions as a function of a different rate or a different intensity of adsorption on supports activated with different hydrophobic groups (butyl-, phenyl- and octyl-agarose). Thus, although RNL seemed to be a homogeneous sample by SDS-PAGE, it could be separated, via sequential adsorption on the different supports, into three different fractions with very different thermal stability and substrate specificity. For example, one fraction hydrolyzed more rapidly ethyl acetate than ethyl butyrate, while another hydrolyzed the acetate ester 7-fold slower than the butyrate. Similar results were obtained with samples of CRL. Again, we could obtain three different fractions showing very different properties. For example, enantioselectivity for the hydrolysis of (R,S) 2-hydroxy-4-phenylbutanoic acid ethyl ester ranged from 1.2 to 12 for different CRL fractions. It seems that very slight structural differences may promote a quite different interfacial adsorption of lipases on hydrophobic supports as well as a quite different catalytic behavior. In this way, this new 'interfacial affinity chromatography' seems to be very suitable for an easy separation of such slightly different lipase forms.
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Affiliation(s)
- P Sabuquillo
- Departamento de Biocatalisis, Instituto de Catalisis, CSIC, Campus de la Universidad Autonoma, Cantoblanco, 28049 Madrid, Spain
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163
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Berka RM, Rey MW, Brown KM, Byun T, Klotz AV. Molecular characterization and expression of a phytase gene from the thermophilic fungus Thermomyces lanuginosus. Appl Environ Microbiol 1998; 64:4423-7. [PMID: 9797301 PMCID: PMC106663 DOI: 10.1128/aem.64.11.4423-4427.1998] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The phyA gene encoding an extracellular phytase from the thermophilic fungus Thermomyces lanuginosus was cloned and heterologously expressed, and the recombinant gene product was biochemically characterized. The phyA gene encodes a primary translation product (PhyA) of 475 amino acids (aa) which includes a putative signal peptide (23 aa) and propeptide (10 aa). The deduced amino acid sequence of PhyA has limited sequence identity (ca. 47%) with Aspergillus niger phytase. The phyA gene was inserted into an expression vector under transcriptional control of the Fusarium oxysporum trypsin gene promoter and used to transform a Fusarium venenatum recipient strain. The secreted recombinant phytase protein was enzymatically active between pHs 3 and 7.5, with a specific activity of 110 micromol of inorganic phosphate released per min per mg of protein at pH 6 and 37 degrees C. The Thermomyces phytase retained activity at assay temperatures up to 75 degrees C and demonstrated superior catalytic efficiency to any known fungal phytase at 65 degrees C (the temperature optimum). Comparison of this new Thermomyces catalyst with the well-known Aspergillus niger phytase reveals other favorable properties for the enzyme derived from the thermophilic gene donor, including catalytic activity over an expanded pH range.
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Affiliation(s)
- R M Berka
- Novo Nordisk Biotech, Davis, California 95616-4880, USA
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164
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Xu F, Berka RM, Wahleithner JA, Nelson BA, Shuster JR, Brown SH, Palmer AE, Solomon EI. Site-directed mutations in fungal laccase: effect on redox potential, activity and pH profile. Biochem J 1998; 334 ( Pt 1):63-70. [PMID: 9693103 PMCID: PMC1219662 DOI: 10.1042/bj3340063] [Citation(s) in RCA: 200] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A Myceliophthora thermophila laccase and a Rhizoctonia solani laccase were mutated on a pentapeptide segment believed to be near the type-1 Cu site. The mutation L513F in Myceliophthora laccase and the mutation L470F in Rhizoctonia laccase took place at a position corresponding to the type-1 Cu axial methionine (M517) ligand in Zucchini ascorbate oxidase. The triple mutations V509L,S510E,G511A in Myceliophthora laccase and L466V,E467S,A468G in Rhizoctonia laccase involved a sequence segment whose homologue in ascorbate oxidase is flanked by the M517 and a type-1 Cu-ligating histidine (H512). The single mutation did not yield significant changes in the enzymic properties (including any significant increase in the redox potential of the type-1 Cu). In contrast, the triple mutation resulted in several significant changes. In comparison with the wild type, the Rhizoctonia and Myceliophthora laccase triple mutants had a phenol-oxidase activity whose pH optimum shifted 1 unit lower and higher, respectively. Although the redox potentials were not significantly altered, the Km, kcat and fluoride inhibition of the laccases were greatly changed by the mutations. The observed effects are interpreted as possible mutation-induced structural perturbations on the molecular recognition between the reducing substrate and laccase and on the electron transfer from the substrate to the type-1 Cu centre.
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Affiliation(s)
- F Xu
- Novo Nordisk Biotech, 1445 Drew Avenue, Davis, CA 95616, USA.
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