Disease relevance of Laccase

• The CotA laccase from the endospore coat of Bacillus subtilis has been crystallized in the presence of the non-catalytic co-oxidant 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS), and the structure was determined using synchrotron radiation [1].
• The fungus Cryptococcus neoformans is an opportunistic human pathogen that causes a life-threatening meningoencephalitis by expression of virulence factors such as melanin, a black pigment produced by the cell wall-associated enzyme laccase [2].
• 16-O- Acetylvindoline (1a) was oxidatively transformed into an iminium derivative (2a) by copper oxidases (laccase and human ceruloplasmin), an unknown enzyme system(s) of Streptomyces griseus, and the chemical oxidizing agent 2,3-dichloro-5,6- dicyano -1,4-benzoquinone ( DDQ ) [3].
• Cryptococcus neoformans is an important opportunistic pathogen in immunocompromised patients, including those with human immunodeficiency virus, and expresses a virulence-associated laccase which is believed to oxidize brain catecholamines and iron as a defense against host immune cells [4].
• While laccase of Cryptococcus neoformans is implicated in the virulence of the organism, our recent studies showing absence of melanin in the infected mouse brain has led us to a search for alternative roles for laccase in cryptococcosis [5].

Psychiatry related information on Laccase

• In the enzymatic prebleaching the enzyme laccase was used at two conditions of pH and temperature, whereas the reaction time was fixed at 1 h in all pretreatments [6].

High impact information on Laccase

• Effect of the laccase gene CNLAC1, on virulence of Cryptococcus neoformans [7].
• When this base change was introduced into CNLAC1 by site-directed mutagenesis, it no longer transformed mel2 to Mel+, indicating the importance of this histidine in laccase activity [7].
• NOT1 was found to act as an intermediary transcriptional repressor of laccase [8].
• In this study, a virulence-associated DEAD-box RNA helicase-encoding gene (VAD1) was isolated from a mutant defective in the virulence factor laccase [8].
• TT10 encodes a protein with strong similarity to laccase-like polyphenol oxidases [9].

Chemical compound and disease context of Laccase

• Substrate and dioxygen binding to the endospore coat laccase from Bacillus subtilis [1].
• Loss of cytochrome c oxidase activity and acquisition of resistance to quinone analogs in a laccase-positive variant of Azospirillum lipoferum [10].
• Here we report the enzymological characterization of EpoA, a laccase-like extracytoplasmic phenol oxidase produced by Streptomyces griseus [11].
• 2,6-Dimethoxyphenol is a versatile substrate for Pyricularia oryzae laccase, PpoA from Marinomonas mediterranea, phenoxazinone synthase from Streptomyces antibioticus and mammalian ceruloplasmin [12].

Biological context of Laccase

• Based on amino acid sequence comparison between these proteins, putative copper ligands of N. crassa laccase are proposed [13].
• Low-temperature magnetic circular dichroism studies of native laccase: spectroscopic evidence for exogenous ligand bridging at a trinuclear copper active site [14].
• The laccase (benzenediol:oxygen oxidoreductase, EC 1.10.3.2) gene from Neurospora crassa was cloned and part of its nucleotide sequence corresponding to the carboxyl-terminal region of the protein has been determined [13].
• The analyzed carboxyl-terminal region of laccase exhibits a striking sequence homology to the carboxyl-terminal part of the third homology unit of the multicopper oxidase ceruloplasmin and to a smaller extent, to the low molecular weight blue copper proteins plastocyanin and azurin [13].
• Laccase is implicated in a wide spectrum of biological activities and, in particular, plays a key role in morphogenesis, development and lignin metabolism in fungi and plants [15].

Anatomical context of Laccase

• Finally, we show that these biological effects observed in the C1 deletion mutant are mediated by alteration of cell wall integrity and displacement of laccase from the cell wall [2].
• Laccase protects Cryptococcus neoformans from antifungal activity of alveolar macrophages [5].
• Infection with laccase-positive (melanotic) C. neoformans cells also elicited higher MCP-1 levels and more infiltrating leukocytes than did infection with laccase-negative cells [16].
• The genes were verified as encoding active laccases by heterologous expression in tobacco cells and demonstration of laccase activity in extracts from transformed tobacco cell lines [17].
• Liver melanosome extracts display a very strong laccase (dimethoxyphenoloxidase) activity but spleen extracts do not [18].

Associations of Laccase with other chemical compounds

• The SKU5 gene belongs to a 19-member gene family designated SKS (SKU5 Similar) that is related structurally to the multiple-copper oxidases ascorbate oxidase and laccase [19].
• Spectroscopic and kinetic studies on the oxygen-centered radical formed during the four-electron reduction process of dioxygen by Rhus vernicifera laccase [20].
• The 14N ENDOR, and, therefore, the structure, of this site corresponds extremely closely to that of the laccase type 3 (Cu(II) [21].
• Under the catalysis of laccase, the apparent oxidation rates (kcat and kcat/Km) of two nonphenolic substrates, potassium ferrocyanide and 2,2'-azinobis-(3-ethylbenzthiazoline-6-sulfonic acid), decreased monotonically as the pH increased [22].
• This study investigates the possible role of a laccase and a FAD-dependent aryl alcohol oxidase (veratryl alcohol oxidase, VAO) excreted by the basidiomycete Pleurotus ostreatus [23].
• From a detailed analysis of the catalytic reduction of dioxygen by laccase in the presence of a one-electron redox mediator it can be concluded that the immobilized enzyme remains as active as in homogeneous solution [24].

Gene context of Laccase

• In this study, cDNA and genomic clones encoding a homologue of the yeast gene anti-oxidant 1 (ATX1) from the white-rot fungus Trametes versicolor, a basidiomycete known to produce several laccase isoenzymes involved in lignin degradation, were identified [25].
• A number of genes have been implicated in the regulation of laccase and melanization, including IPC1, GPA1, MET3, and STE12 [26].
• The protein encoded by the RSp1530 locus is a multicopper protein with laccase activity [27].
• Serotype D yeasts were transformed with a plasmid containing the CNA1 cDNA in an antisense orientation under the control of the inducible GAL7 promoter, and serotype A yeasts were transformed with a plasmid containing the LAC1 cDNA in an antisense orientation under the control of the constitutive actin promoter [28].
• Overexpression of ire1 in a T. reesei strain that expresses a foreign protein (laccase 1 from Phlebia radiata), results in up-regulation of the UPR pathway, as indicated by the increased expression levels of the known UPR target genes bip1 and pdi1 [29].

Analytical, diagnostic and therapeutic context of Laccase

• Reverse transcriptase-polymerase chain reaction detected CNLAC1 transcript, indicating that laccase may be produced in the infected host [7].
• The structure of laccase from the fungus Coprinus cinereus has been determined by X-ray crystallography at a resolution of 2.2 A [15].
• Although transcription and protein expression were somewhat reduced, laccase protein was found to be successfully translated and correctly targeted to the cell wall in the Deltavph1 mutant as shown by Western blot and immuno-electron microscopy, despite a complete lack of laccase activity [30].
• We report here the cDNA and protein sequences, the post-translational modifications, the crystallization and X-ray structure determination of a laccase from the white-rot fungus Rigidoporus lignosus [31].
• Catalytic currents were observed in the presence of the biological substrate oxygen, indicating that laccase activity is retained throughout the immobilization process [32].

References