<p>Cell division in the Gram-positive bacterium <i>Streptomyces coelicolor</i> starts with the assembly of the tubulin homologue FtsZ into a cytokinetic ring (the Z ring) at the site of septation. In stark contrast to the binary fission of most bacteria, the syncytial hyphal cells of <i>S. coelicolor</i> exploit two types of cell division with strikingly different outcomes depending on the developmental stage. </p><p>The main goal of this study has been to identify developmental mechanisms that modulate this differential performance of the basic cell division machinery.</p><p>By isolation and characterization of a non-sporulating <i>ftsZ</i> mutant, we demonstrated that the requirements for Z-ring formation differ between the two types of septation. The <i>ftsZ17</i>(Spo) mutation abolished septation without overtly affecting vegetative growth. This mutant was defective in the assembly of FtsZ into regularly spaced Z rings in sporogenic hyphae, suggesting that the assembly of Z rings is developmentally controlled during sporulation.</p><p>An FtsZ-EGFP translational fusion was constructed and used to visualize the progression of FtsZ ring assembly in vivo. This revealed that polymerization of FtsZ occurred throughout the sporogenic cell, with no evidence for pre-determined nucleation sites, and that the placement of multiple Z rings is a dynamic process and involves remodeling of spiral-shaped FtsZ intermediates into regularly spaced rings. </p><p>The dynamics of the multiple Z-rings assembly during sporulation was perturbed by the action of the protein CrgA, which is important for coordinating growth and cell division in sporogenic hyphae. CrgA was also found to affect the timing of <i>ftsZ</i> expression and the turnover of the FtsZ protein. </p><p><i>S. coelicolor</i> is the main genetic model of the streptomycetes, which are major industrial antibiotic producers. The control of cell division in these organisms differs from that of other bacteria like <i>Escherichia coli</i>. Thus, it is of fundamental importance to clarify how the streptomycetes reproduce themselves. </p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-6412 |
| Date | January 2006 |
| Creators | Grantcharova, Nina |
| Publisher | Uppsala University, Department of Cell and Molecular Biology, Uppsala : Acta Universitatis Upsaliensis |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
| Relation | Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 149 |
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