title: Potential biological role of laccase from the sponge Suberites domuncula as an antibacterial defense component.
abstract: BACKGROUND
  Laccases are copper-containing enzymes that catalyze the oxidation of a wide variety of phenolic substrates.
  
  
  METHODS
  We describe the first poriferan laccase from the marine demosponge Suberites domuncula.
  
  
  RESULTS
  This enzyme comprises three characteristic multicopper oxidase homologous domains. Immunohistological studies revealed that the highest expression of the laccase is in the surface zone of the animals. The expression level of the laccase gene is strongly upregulated after exposure of the animals to the bacterial endotoxin lipopolysaccharide. To allow the binding of the recombinant enzyme to ferromagnetic nanoparticles, a recombinant laccase was prepared which contained in addition to the His-tag, a Glu-tag at the N-terminus of the enzyme. The recombinant laccase was enzymatically active. The apparent Michaelis constant of the enzyme is 114 μM, using syringaldazine as substrate. Exposure of E. coli to the nanoparticles, coated with Glu-tagged laccase, and to the mediator 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) in the presence of lignin, as the oxidizable substrate, resulted in an almost complete inhibition of colony formation. Quantitative studies of the effect of the laccase-coated iron oxide nanoparticles were performed using E. coli grown in suspension in reaction tubes within a magnetic nanoparticle separator.
  
  
  CONCLUSIONS
  This newly designed magnetic nanoparticle separator allowed a removal of the nanoparticles after terminating the reaction. Using this system, a strong dose-dependent inhibition of the growth of E. coli by the laccase iron oxide nanoparticles was determined.
  
  
  CONCLUSIONS
  From our data we conclude that the sponge laccase is involved in the anti-bacterial defense of the sponge organism.
authors.affiliation: Institute of Karst Geology, CAGS, No. 50 Qixing Road, 541004 Guilin, Guangxi, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.affiliation: ERC Advanced Investigator Grant Research Group at Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, D-55128 Mainz, Germany.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Wang
authors.affiliation: ERC Advanced Investigator Grant Research Group at Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, D-55128 Mainz, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Korzhev
authors.affiliation: ERC Advanced Investigator Grant Research Group at Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, D-55128 Mainz, Germany.
authors.forename: Heinz C
authors.initials: HC
authors.lastname: Schröder
authors.affiliation: ERC Advanced Investigator Grant Research Group at Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, D-55128 Mainz, Germany.
authors.forename: Thorben
authors.initials: T
authors.lastname: Link
authors.affiliation: Johannes Gutenberg University Mainz, Institute of Inorganic Chemistry and Analytical Chemistry, Duesbergweg 10-14, D-55128 Mainz, Germany.
authors.forename: Muhammad Nawaz
authors.initials: MN
authors.lastname: Tahir
authors.affiliation: NanotecMARIN GmbH, Duesbergweg 6, D-55128 Mainz, Germany.
authors.forename: Bärbel
authors.initials: B
authors.lastname: Diehl-Seifert
authors.affiliation: ERC Advanced Investigator Grant Research Group at Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Duesbergweg 6, D-55128 Mainz, Germany. Electronic address: wmueller@uni-mainz.de.
authors.forename: Werner E G
authors.initials: WE
authors.lastname: Müller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000378:metabolism*; D055162:Biocatalysis; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D005290:Ferric Compounds / Q000737:chemistry; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006835:Hydrazones / Q000378:metabolism; D007700:Kinetics; D042845:Laccase / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D008031:Lignin / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008969:Molecular Sequence Data; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity; D010084:Oxidation-Reduction; D010802:Phylogeny; D011994:Recombinant Proteins / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D047233:Suberites / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D005290:Ferric Compounds; D006835:Hydrazones; D008070:Lipopolysaccharides; D011994:Recombinant Proteins; C009370:syringaldazine; C000499:ferric oxide; D008031:Lignin; D042845:Laccase
keywords: Anti-bacterial defense; Copper; Ferromagnetic particles; Laccase; Lignin; Sponges