A novel extracytoplasmic phenol oxidase of Streptomyces: its possible involvement in the onset of morphogenesis The DDBJ accession number for the sequence reported in this paper is AB056583.

Abstract

Exogenous addition of copper stimulates cellular differentiation inStreptomyces spp. Several lines of evidence suggested a parallel correlation between the stimulatory effect of copper and phenol-oxidizing enzyme activities in Streptomyces griseus. Here a novel extracytoplasmic phenol oxidase (EpoA) associated with cellular development of this organism was identified and characterized. EpoA activity, examined by an in-gel stain procedure with N,N'-dimethyl-p-phenylenediamine sulfate as a substrate, was repressed by glucose and induced by copper supplied in the medium. The enzyme activity was abolished and markedly reduced in the mutants for A-factor biosynthesis and amfR, respectively, which suggested that the activity of the enzyme depends on those essential regulators for morphogenesis in S. griseus. EpoA protein was purified to homogeneity and the N-terminal amino acid sequence was determined. A homologous sequence identified in the genomic database of Streptomyces coelicolorA3(2) was used as a probe to clone the complete epoA gene of S. griseus. The deduced amino acid sequence of EpoA revealed that the mature protein with a molecular mass of 34 kDa was preceded by a signal peptide consisting of 34 aa, consistent with EpoA being a secreted enzyme. EpoA was predicted to be a laccase-type oxidase by not only the sequence similarity, but its substrate selectivity, oxidizing not tyrosine but dihydroxyphenylalanine (DOPA) to generate melanin pigment. Introduction of epoA on a plasmid partially restored both the EpoA activity and aerial mycelium productivity in an A-factor-deficient mutant. Exogenous supplementation of a substance synthesized by purified EpoA from DOPA stimulated cellular differentiation in S. griseus and several other species. Ultrafiltration indicated that the molecular mass of the putative stimulant synthesized by EpoA is between 500 and 1000 Da.

Crystallization and preliminary X-ray diffraction analysis of a putative two-domain-type laccase from a metagenome

“…SLAC was identified in the genomic sequence of Streptomyces coelicolor (Machczynski et al, 2004) and lacks the second domain of typical three-domain-type laccases. EpoA, an extracytoplasmic phenol oxidase, from S. griseus is also a two-domain laccase and is produced upon induction with copper in the medium (Endo et al, 2002(Endo et al, , 2003.…”

The Determination of Assay for Laccase of Bacillus subtilis WPI with Two Classes of Chemical Compounds as Substrates

“…The most extensively studied applications of laccases include denim finishing [4], pulp delignification, textile dye bleaching, wastewater detoxification and transformation of antibiotics and steroids [5]. Laccases are generally found in plants and fungi [6], but they have also been reported in a few bacteria including Azospirillum lipoferum [7], Bacillus sphaericus [1], Marinomonas mediterranea [8] and Streptomyces griseus [9]. Although fungal laccases have a higher reduction potential of type I copper than bacterial laccases and this makes them more suitable for commercial applications [10] their use present the following drawbacks: slow growth and difficulty in controlling the glycosylation degree [11].…”

Microbial Decolorization of Various Dyes by a Bacillus subtilis Strain Isolated from an Industrial Effluent Treatment Plant

“…However, the ETL 1979 strain is unable to form melanin in the medium containing copper ions. CotA in B. subtilis has been associated with the formation of a brown pigment [28,29]. Strain ETL 1979, also showed strong resistance to high concentrations of NaCl; it can survive in 10% NaCl.…”