title: Purification and characterization of laccase from Sinorhizobium meliloti and analysis of the lacc gene.
abstract: The soil native bacterial strains were screened for laccase activity. Bacterial strain L3.8 with high laccase activity was identified as Sinorhizobium meliloti. The crude intracellular L3.8 enzyme extract was able to oxidize typical diagnostic substrates of plant and fungal laccases. Laccase L3.8 was purified 81-fold with a yield of 19.5%. The molecular mass of the purified bacterial laccase was found to be 70.0kDa and its pI was 4.77. UV-vis spectrum showed that L3.8 protein is a multicopper oxidase. The carbohydrate content of the purified enzyme was estimated at 3.2%. Moreover, the laccase active fraction was characterized in terms of kinetics, temperature, and pH optima as well as the effect of various chemical compounds on the laccase activity, and antioxidant properties, which indicated that the L3.8 laccase had unique properties that might be important in biotechnological applications. The lacc gene encoding S. meliloti laccase was cloned and characterized. The full-length sequence of 1950bp encoded a protein of 649 aa preceded by a signal peptide consisting of 26aa. Laccase L3.8 shared significant structural features characteristic of other laccases, including the conserved regions of four histidine-rich copper-binding sites. Potential biotechnological importance of a newly identified laccase is discussed.
authors.affiliation: Department of Biochemistry, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland. Electronic address: anna.pawlik@poczta.umcs.lublin.pl.
authors.forename: Anna
authors.initials: A
authors.lastname: Pawlik
authors.affiliation: Department of Biochemistry, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland; Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Wójcik
authors.affiliation: Department of Biochemistry, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
authors.forename: Karol
authors.initials: K
authors.lastname: Rułka
authors.affiliation: Department of Biochemistry, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
authors.forename: Karolina
authors.initials: K
authors.lastname: Motyl-Gorzel
authors.affiliation: Department of Biochemistry, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Osińska-Jaroszuk
authors.affiliation: Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Wielbo
authors.affiliation: Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Marek-Kozaczuk
authors.affiliation: Department of Genetics and Microbiology, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Skorupska
authors.affiliation: Department of Biochemistry, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
authors.forename: Jerzy
authors.initials: J
authors.lastname: Rogalski
authors.affiliation: Department of Biochemistry, Maria Curie-Skłodowska University, Akademicka 19, 20-033 Lublin, Poland.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Janusz
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D042845:Laccase / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D016962:Sinorhizobium meliloti / Q000201:enzymology / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D042845:Laccase
keywords: Antioxidant; Laccase; Sinorhizobium meliloti