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Updated: Feb 7, 2026

Visual and Microscopic Evaluation of Streptomyces Developmental Mutants
Published on: September 12, 2018
Extracytoplasmic diaphorase activity of Streptomyces coelicolor A3(2)
Ken-Ichi Oinuma1, Itaru Yamaguchi1, Daiki Shindo1
1Life Science Research Center, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa, 252-0880, Japan.
Abstract:
Metabolism and utilization of plant-derived aromatic substances are fundamental to the saprophytic growth of Streptomyces. Here, we studied an enzyme activity reducing 2,6-dichlorophenolindophenol and nitroblue tetrazolium in the culture supernatant of Streptomyces coelicolor A3(2). N-terminal amino acid sequencing of a nitroblue tetrazolium-reducing enzyme revealed that the enzyme corresponds to the SCO2180 product. The protein exhibited a marked similarity with dihydrolipoamide dehydrogenase, the E3 subunit of 2-oxo-acid dehydrogenase complex. A recombinant SCO2180 protein formed a homodimer and exhibited a diaphorase activity catalyzing NADH-dependent reduction of various quinonic substrates. Similar nitroblue tetrazolium-reducing activities were observed for other Streptomyces strains isolated from soil, implying that the diaphorase-catalyzed reduction of quinonic substances widely occurs in the extracytoplasmic space of Streptomyces.
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