SepF: a link between cell division and polar growth in Streptomyces coelicolor

Cassettari, Gemma (2022) SepF: a link between cell division and polar growth in Streptomyces coelicolor. Doctoral thesis, University of East Anglia.

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Abstract

Cell division in bacteria requires the polymerisation of the tubulin homologue, FtsZ, into Z-rings. Homologues of FtsZ are well conserved among bacteria and FtsZ is present even in some archaea. Polymerisation of FtsZ occurs in a GTP-dependent manner with individual subunits treadmilling along the protofilaments and directing the movement of the late divisome proteins involved in peptidoglycan (PG) synthesis during septum formation. Positioning of the Z-ring in Escherichia coli and Bacillus subtilis is negativity regulated by the synergistic work of the Min system and the nucleoid occlusion system, which prevents the formation of Z-rings at the poles or over the chromosomes. In addition, in E. coli the positive regulators, FtsA and ZipA, anchor the Z-ring to the cell membrane whilst in B. subtilis in the absence of ZipA, cells rely on FtsA and SepF.

Septum formation in the filamentous bacterium Streptomyces coelicolor requires the polymerisation of FtsZ into regularly spaced Z-rings along the multi genomic aerial hyphae. S. coelicolor lacks any obvious Min and Nucleoid occlusion systems. However in S. coelicolor FtsZ has been shown to be positively regulated by SsgB and three SepF homologues have been identified.

In this work we continued the characterisation of SepF, encoded in the DCW gene cluster. First, a thorough analysis of the ΔsepF phenotype including complementation of the knockout mutant is presented. Using a translational Egfp fusion, the localisation of SepF during sporulation and the dependence of SepF on FtsZ and Scy, involved in controlling polar growth, was tested. Bacterial two-hybrid assays were used to establish possible new interactions between SepF and proteins involved in both cell division and polar growth, and some of these novel interactions were rationalised. Finally, actinorhodin synthesis was compared between the wild-type and sepF strains to test the effect of compartmentalisation on antibiotic production.

Item Type:	Thesis (Doctoral)
Faculty \ School:	Faculty of Science > School of Biological Sciences
Depositing User:	Chris White
Date Deposited:	09 Aug 2022 10:44
Last Modified:	09 Aug 2022 10:45
URI:	https://ueaeprints.uea.ac.uk/id/eprint/87146
DOI:

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