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Title: Developmental osmo adaptation in the complex differential actinomycete, Streptomyces coelicolor A3C2
Author: Bishop, A. L.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2004
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In Streptomycetes, maintenance of turgor pressure is essential for the extension of aerial hyphae during development. The necessity of osmotic adaptation during development was highlighted in this study by the discovery of a response regulator, osaB (SCO5749); which acts as an integral node in a signalling pathway that responds to conditions of high osmolarity. Disruption of osaB by transposon mutagenesis resulted in a conditional bald mutant with uncoordinated antibiotic production. The concentration of osmolyte in the media influences this developmental phenotype. Adjacent to the response regulator is a hybrid histidine kinase, which is not essential for development. S1 nuclease protection assays established that osaB has its own promoter. Using luciferase and eGPF reporter genes to monitor expression patterns revealed that expression of both genes is unregulated in the presence of external osmolyte. Stress and development are intricately connected in S. coelicolor. The presence of nine SigB-like sigma factors and multiple anti-sigma factors and antagonists expands the opportunity for cross talk between complex signalling networks, integrating and coordinating the stress response with development and metabolism. Evidence supporting this concept is accumulating from analysis of individual genes (Cho et al., 2001; Kelemen et al., 2001; Viollier et al., 2003a). This study used transposon mutagenesis to target several putative regulators of SigB in conjunction with a carbohydrate metabolism operon. osaC (SCO5747), a predicted stress sensor and regulator of SigB is conditionally required for development but does not coordinate antibiotic production. It may act as a switch protein, modulating the activity of a sigma factor via phosphorylation. Disruption of the α-amylase gene, pep1B (SCO7335) resulted in a conditional bald phenotype resembling that of osaBC mutants. This developmental block might be attributed to the disruption of either pep1B or downstream SCO7337, a putative trehalose synthase.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available