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Deprogrammed sporulation in Streptomyces
Yasuo Ohnishi1, Jeong-Woo Seo, Sueharu Horinouchi
1Department of Biotechnology, Graduate School of Agriculture and Life Sciences, University of Tokyo, Japan.
FEMS Microbiology Letters
|November 9, 2002
Summary
Streptomyces bacteria can form spores in substrate hyphae, not just aerial hyphae. This ectopic sporulation, triggered by glucose and an ATP-binding cassette transporter mutation, reveals a latent developmental potential.
Area of Science:
- Microbiology
- Bacterial Development
- Cell Biology
Background:
- Streptomyces bacteria normally form spores from aerial hyphae after substrate hyphae lysis.
- Ectopic sporulation in substrate or vegetative hyphae suggests a broader potential for spore formation.
Purpose of the Study:
- To investigate the mechanisms and conditions underlying ectopic sporulation in Streptomyces.
- To identify genetic factors influencing the switch between vegetative growth and sporulation in substrate hyphae.
Main Methods:
- Analysis of a Streptomyces griseus mutant (NP4) with a defective ATP-binding cassette (ABC) transporter.
- Overexpression of an ABC transporter's substrate-binding protein in wild-type Streptomyces.
- Microscopic observation of hyphal development and sporulation on various media, including glucose-containing media.
Main Results:
- A mutation in an ABC transporter regulatory system (NP4 strain) induced ectopic spore formation in substrate hyphae on glucose-containing medium.
- Overexpression of an ABC transporter substrate-binding protein in wild-type strains caused ectopic septation and sporulation in young substrate hyphae, triggered by glucose.
- Ectopic spores exhibited normal germination and sporulation was independent of the developmental hormone A-factor.
Conclusions:
- Streptomyces substrate hyphae possess the inherent potential for spore development, which is normally repressed.
- Strict repression of septum formation in substrate mycelium is crucial for programmed Streptomyces development.
- Glucose acts as a signal, potentially mediated by ABC transporters, to trigger ectopic sporulation in substrate hyphae.