Nucleoid Condensation and Cell Division in Escherichia coli MX74T2 ts52 After Inhibition of Protein Synthesis

AUTOR(ES)

Zusman, David R.

RESUMO

The reorganization of the bacterial nucleoid of an Escherichia coli mutant, MX74T2 ts52, was studied by electron microscopy after protein synthesis inhibition by using whole mounts of cell ghosts, ultrathin-sectioning, and freeze-etching. The bacterial nucleoid showed two morphological changes after chloramphenicol addition: deoxyribonucleic acid (DNA) localization and DNA condensation. DNA localization was observed 10 min after chloramphenicol addition; the DNA appeared as a compact, solid mass. DNA condensation was observed at 25 min; the nucleoid appeared as a cytoplasm-filled sphere, often opened at one end. Ribosomes were observed in the center. Giant nucleoids present in some mutant filaments showed fused, spherical nucleoids arranged linearly, suggesting that the tertiary structure of the nucleoid reflects the number of replicated genomes. Inhibitors which directly or indirectly blocked protein synthesis and caused DNA condensation were chloramphenicol, puromycin, amino acid starvation, rifampicin, or carbonyl cyanide m-chlorophenyl hydrazone. All inhibitors that caused cell division in the mutant also caused condensation, although some inhibitors caused condensation without cell division. Nucleoid condensation appears to be related to chromosome structure rather than to DNA segregation upon cell division.

Documentos Relacionados

• Nucleoid-Independent Identification of Cell Division Sites in Escherichia coli
• Cell Division During Inhibition of Deoxyribonucleic Acid Synthesis in Escherichia coli
• Nucleoid partitioning and the division plane in Escherichia coli.
• Cell length, nucleoid separation, and cell division of rod-shaped and spherical cells of Escherichia coli.
• Morphokinetic Reaction of Streptococcus faecalis (ATCC 9790) Cells to the Specific Inhibition of Macromolecular Synthesis: Nucleoid Condensation on the Inhibition of Protein Synthesis1