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Title: Analysis of SEDS proteins and their cognate PBPs in Streptomyces coelicolor
Author: Mistry, Bhavesh V.
Awarding Body: Swansea University
Current Institution: Swansea University
Date of Award: 2008
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The rodA and ftsW genes encode polytopic membrane proteins that are essential for bacterial cell elongation and division, respectively. These genes are highly conserved among bacteria with a peptidoglycan cell wall and belong to the SEDS ("shape, elongation, division, and sporulation") gene family. Each SEDS gene is invariably linked with a cognate class B high-molecular weight penicillin-binding protein (HMW PBP) gene. Four such pairs of genes are found in the genome of filamentous differentiating Streptomyces coelicolor. This study focused on characterization of four SEDS genes [SC02085 (ftsW), SC02607 (sfr), SC03846 (rodA) and SC05302 (rodA2)] and SC02090 (ftsi) and SC02608 ipbp2) [cognate HMW PBP genes ftsWand sfr, respectively]. Computational analysis of each SEDS gene locus revealed that each gene is a part of specific gene cluster. Construction of disruption mutants of each SEDS gene revealed ftsW, sfr and rodA2 are dispensable for growth and survival of S. coelioclor, whereas rodA is essential. Mutation of sfr or rodA2 did not cause gross changes to growth and septation of the organism. However, the mutation in sfr made the spores susceptible to heat, SDS and cell wall specific antibiotics. Similar effects were observed in the php2 (cognate HMW PBP gene of sfr) disrupted mutant. The susceptibility of the spores of sfr and php2 mutants to such a physical and chemical stress implies an important role of these genes in spore wall synthesis. Disruption of either or the cognate ftsI gene blocked the formation of sporulation septation in aerial hyphae. The inability of spiral polymers of FtsZ to reorganize into rings in aerial hyphae of these mutants indicates an early pivotal role of an FtsW-FtsI complex in cell division. Mutants of ftsQ were also unable to sporulate and the cytological analysis of this mutant showed that it was blocked at a later stage in cell division, during septum closure. Analysis of FtsZ distribution in ftsQ mutant aerial hyphae revealed that concerted assembly of the complete divisome was not required for Z ring stabilization in this mutant. Complete cross-wall formation in the vegetative hyphae of all three fts mutants imply that the typical bacterial divisome functions specifically during non-essential sporulation septation. Thus, it provides a unique opportunity to investigate the function and dependencies of individual components of the divisome in vivo.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available