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1.
Microbiology (Reading) ; 167(2)2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33400639

RESUMO

The sporulating, filamentous soil bacterium Streptomyces venezuelae ATCC 10712 differentiates under submerged and surface growth conditions. In order to lay a solid foundation for the study of development-associated division for this organism, a congenic set of mutants was isolated, individually deleted for a gene encoding either a cytoplasmic (i.e. ftsZ) or core inner membrane (i.e. divIC, ftsL, ftsI, ftsQ, ftsW) component of the divisome. While ftsZ mutants are completely blocked for division, single mutants in the other core divisome genes resulted in partial, yet similar, blocks in sporulation septum formation. Double and triple mutants for core divisome membrane components displayed phenotypes that were similar to those of the single mutants, demonstrating that the phenotypes were not synergistic. Division in this organism is still partially functional without multiple core divisome proteins, suggesting that perhaps other unknown lineage-specific proteins perform redundant functions. In addition, by isolating an ftsZ2p mutant with an altered -10 region, the conserved developmentally controlled promoter was also shown to be required for sporulation-associated division. Finally, microscopic observation of FtsZ-YFP dynamics in the different mutant backgrounds led to the conclusion that the initial assembly of regular Z rings does not per se require the tested divisome membrane proteins, but the stability of Z rings is dependent on the divisome membrane components tested. The observation is consistent with the interpretation that Z ring instability likely results from and further contributes to the observed defects in sporulation septation in mutants lacking core divisome proteins.


Assuntos
Proteínas de Bactérias/metabolismo , Divisão Celular , Streptomyces/citologia , Proteínas de Bactérias/genética , Divisão Celular/genética , Segregação de Cromossomos , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Mutação , Fenótipo , Regiões Promotoras Genéticas , Esporos Bacterianos/citologia , Esporos Bacterianos/genética , Esporos Bacterianos/fisiologia , Streptomyces/genética , Streptomyces/fisiologia
2.
Mol Microbiol ; 112(1): 184-198, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31002418

RESUMO

Bacterial cell division is orchestrated by the Z ring, which is formed by single-stranded treadmilling protofilaments of FtsZ. In Streptomyces, during sporulation, multiple Z rings are assembled and lead to formation of septa that divide a filamentous hyphal cell into tens of prespore compartments. We describe here mutant alleles of ftsZ in Streptomyces coelicolor and Streptomyces venezuelae that perturb cell division in such a way that constriction is initiated along irregular spiral-shaped paths rather than as regular septa perpendicular to the cell length axis. This conspicuous phenotype is caused by amino acid substitutions F37I and F37R in ß strand S2 of FtsZ. The F37I mutation leads, instead of regular Z rings, to formation of relatively stable spiral-shaped FtsZ structures that are capable of initiating cell constriction. Further, we show that the F37 mutations affect the polymerization properties and impair the cooperativity of FtsZ assembly in vitro. The results suggest that specific residues in ß strand S2 of FtsZ affect the conformational switch in FtsZ that underlies assembly cooperativity and enable treadmilling of protofilaments, and that these features are required for formation of regular Z rings. However, the data also indicate FtsZ-directed cell constriction is not dependent on assembly cooperativity.


Assuntos
Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Proteínas do Citoesqueleto/genética , Proteínas do Citoesqueleto/metabolismo , Streptomyces/metabolismo , Sequência de Aminoácidos/genética , Substituição de Aminoácidos/genética , Divisão Celular/genética , Citocinese/genética , Citoesqueleto/metabolismo , Microscopia de Fluorescência/métodos , Mutação , Polimerização , Conformação Proteica em Folha beta/genética , Esporos Bacterianos/genética , Streptomyces/genética , Streptomyces coelicolor/genética
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