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Title: Production of the calcium-dependent antibiotic (CDA) by Streptromyces coelicolor and Streptomyces lividans : molecular biology of cdaR and other genes from the cda cluster
Author: Hayes, Angela Elizabeth
ISNI:       0000 0004 2679 0514
Awarding Body: The University of Manchester
Current Institution: University of Manchester
Date of Award: 2001
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The calcium-dependent antibiotic (CDA) is a non-ribosomally synthesised lipopeptide produced by Streptomyces coelicolor A3(2). The cda biosynthesis gene cluster occupies approximately 83 kb at the 10 o'clock region of the chromosome. A gene encoding a positive regulator of CDA production, designated cdaR, had been previously identified. Sequence similarly suggests that CdaR is a member of the Streptomyces antibiotic regulatory protein (SARP) family. CdaR is predicted to be 638 amino acid residues in size with a putative ATP/GTP-binding site motif A located in its C-terminal region. Mapping of the transcription start point of cdaR found that it possesses an unusually long untranslated leader sequence of 358 nt. cdaR transcripts were easily detectable at the earliest time point examined (24 h) and decreased over time. A 0.75 kb in-frame deletion in cdaR abolished CDA production. Nuclease protection experiments, using RNA isolated from a S. coelicolor cdaR deletion mutant, indicated that CdaR is required for transcription of some of the genes within the cda cluster, including itself. His6-tagged CdaR was produced in E. coli. Preliminary evidence from mobility shift assays suggested that CdaR binds directly to the 5' end of cdaR and also possibly to the promoter region of cdaPSI (peptide synthetase 1). Unexpectedly, introducing multiple copies of cdaR (approximately 50 copies/chromosome) into S. coelicolor 2377 and MT1110 did not detectably increase CDA production. Correspondingly cdaR transcripts only increased by ~ 30% in S. coelicolor MT1110 containing multiple copies of cdaR; this result suggests that transcription of cdaR is very tightly regulated.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available