Influence of the culture medium composition on the excreted/secreted proteases from <Emphasis Type="Italic">Streptomyces violaceoruber</Emphasis> |
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Authors: | Juan Giarrizzo José Bubis Antonieta Taddei |
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Institution: | (1) Laboratorio de Quimica de Proteinas, Departamento de Biología Celular, Universidad Simón Bolívar, Valle de Sartenejas, Baruta, Caracas, Venezuela;(2) Laboratorio de Productos naturales, Departamento de Biología Celular, Universidad Simón Bolívar, Valle de Sartenejas, Baruta, Caracas, Venezuela |
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Abstract: | Streptomyces violaceoruber produces two different classes of mycelium, the substrate and the aerial mycelium. Since proteases have been associated with
morphological turnover processes in other Streptomyces species, the presence of excretory/secretory proteolytic activities was investigated here in S. violaceoruber culture supernatants. Various polypeptide bands, with apparent molecular masses ranging from 40 to 180 kDa, were detected
in soy trypticase broth (STB) culture media supernatants following 72 h of growth, using Sodium dodecyl sulfate-polyacrylamide
gel electrophoresis (SDS-PAGE). Zymograms showed the presence of five proteolytic enzymes (Spvio1–5), which migrated as bands
of 167.7, 130.7, 110.7, 48.3 and 40.9 kDa, respectively. The characterization of these proteases by specific inhibitors showed
that Spvio1–4 belong to the serine protease group and Spvio5 corresponds to a cysteine protease. Additionally, Spvio2 and
5 were inhibited by a mixture of EDTA and EGTA, indicating that both require divalent cations. The protease pattern obtained
in STB enriched with glucose was identical to that obtained in STB. However, Spvio3 and 4 were absent when nitrogen was added
to the culture medium. Cell death was fluorescently detected following 72 h of S. violaceoruber growth in STB and in STB that was enriched with glucose. On the contrary, no cell death was detected in nitrogen-enriched
STB media. Additionally, the formation of the aerial mycelium was impaired in solid cultures of STB media enriched with nitrogen.
These results demonstrate that the composition of the media influences the morphological turnover of the colony and the pattern
of excreted/secreted proteases from S. violaceoruber, and suggest that Spvio3 and 4 are involved in the aerial mycelium formation. |
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Keywords: | Proteases Protease inhibitors Streptomyces Morphogenesis Zymograms |
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