Sister chromosome cohesion of <i>Escherichia coli</i>

Sunako, Yumi; Onogi, Toshinari; Hiraga, Sota

doi:10.1046/j.1365-2958.2001.02680.x

Cited by 122 publications

(121 citation statements)

References 32 publications

(51 reference statements)

Supporting

Mentioning

110

Contrasting

Order By: Relevance

“…Mutations of the topA gene encoding topoisomerase I suppress temperature-sensitive growth and anucleate-cell production (16). It has been demonstrated in synchronized cultures that replicated sister chromosomes are associated with one another for substantial times (6,18). In contrast, results in randomly growing cultures in enriched medium appear to be consistent with the model in which replicated sister copies of oriC separate immediately after replication (8).…”

mentioning

confidence: 75%

See 1 more Smart Citation

Mutants Suppressing Novobiocin Hypersensitivity of amukBNull Mutation

Adachi

Hiraga

2003

J Bacteriol

Self Cite

View full text Add to dashboard Cite

The mukB gene is essential for the partitioning of sister chromosomes in Escherichia coli. A mukB null mutant is hypersensitive to the DNA gyrase inhibitor novobiocin. In this work, we isolated mutants suppressing the novobiocin hypersensitivity of the mukB null mutation. All suppressor mutations are localized in or near the gyrB gene, and the four tested clones have an amino acid substitution in the DNA gyrase beta subunit. We found that in the mukB mutant, the process of sister chromosome segregation is strikingly hypersensitive to novobiocin; however, the effect of novobiocin on growth, which was measured by culture turbidity, is the same as that of the wild-type strain.The smtA-mukF-mukE-mukB operon (22) is located at the 21-min map position of the Escherichia coli chromosome. Deletion mutants of each muk gene show common phenotypes, such as frequent production of anucleate cells upon cell division, chromosome guillotining (cutting) by septum closure, and temperature-sensitive growth; however, they are nearly normal in chromosome replication, homologous recombination, mutation frequency, and sensitivity to UV irradiation (10, 11, 22; for a review, see reference 4). MukF, MukE, and MukB form a large complex (22). MukB is a member of the SMC superfamily (9). A MukB-green fluorescent protein fusion protein is localized as one, two, or four foci at regular cellular positions in the presence of both MukF and MukE (12). To examine the function of the MukB protein, many suppressor mutants of mukB mutations have been analyzed (for a review, see reference 4). Mutations of the topA gene encoding topoisomerase I suppress temperature-sensitive growth and anucleate-cell production (16). It has been demonstrated in synchronized cultures that replicated sister chromosomes are associated with one another for substantial times (6, 18). In contrast, results in randomly growing cultures in enriched medium appear to be consistent with the model in which replicated sister copies of oriC separate immediately after replication (8). However, it is hard to determine which model is right from the results of such random cultures, because the actual time of initiation of chromosome replication is not clear in this type of experiment.A mukB null mutant is hypersensitive to novobiocin, an inhibitor (20). Deletion mutants of each of the mukB, mukF, and mukE genes and a deletion mutant lacking all three muk genes are hypersensitive to novobiocin (14). Weitao et al. (20) showed that a seqA null mutation suppressed temperaturesensitive growth, anucleate-cell production, and novobiocin hypersensitivity in the mukB null mutation. Inconsistently, Onogi et al. (14) reported that a seqA or dam null mutation partially suppressed temperature-sensitive growth but failed to suppress the anucleate-cell production and novobiocin hypersensitivity of these muk null mutants.It is not yet clear what the mechanism of the novobiocin hypersensitivity of these muk mutants is. What is the target protein that is hypersensitive to novobiocin in these muk null...

show abstract

mentioning

confidence: 75%

“…This event causes persistent separation of clockwise and counterclockwise replicating regions of the chromosome (4,6,13,18). Protein-protein linkage between clockwise and counterclockwise replicating regions, e.g., by the hemimethylated DNA binding SeqA protein, might be broken off by the event.…”

Section: Discussionmentioning

confidence: 99%

Mutants Suppressing Novobiocin Hypersensitivity of amukBNull Mutation

Adachi

Hiraga

2003

J Bacteriol

Self Cite

View full text Add to dashboard Cite

show abstract

“…These results imply that the bacterial SMC complex may be much closer to condensins than cohesin. Nevertheless, evidence is also available that B. subtilis SMC (or its distant relative MukB in E. coli) may have cohesin-like functions such as keeping together the newly replicated sister DNAs (Sunako et al 2001;Lindow et al 2002b) or promoting DNA repair (Dervyn et al 2004). From an evolutionary point of view, bacterial SMC proteins belong to the main branch of the SMC family that includes SMC1, SMC2, SMC3, and SMC4 but not SMC5 or SMC6 (Cobbe and Heck 2004).…”

Section: Bacterial Smc Linkersmentioning

confidence: 99%

Dynamic molecular linkers of the genome: the first decade of SMC proteins

Losada¹,

Hirano²

2005

Genes Dev.

328

311

View full text Add to dashboard Cite

Structural maintenance of chromosomes (SMC) proteins are chromosomal ATPases, highly conserved from bacteria to humans, that play fundamental roles in many aspects of higher-order chromosome organization and dynamics. In eukaryotes, SMC1 and SMC3 act as the core of the cohesin complexes that mediate sister chromatid cohesion, whereas SMC2 and SMC4 function as the core of the condensin complexes that are essential for chromosome assembly and segregation. Another complex containing SMC5 and SMC6 is implicated in DNA repair and checkpoint responses. The SMC complexes form unique ring-or V-shaped structures with long coiled-coil arms, and function as ATP-modulated, dynamic molecular linkers of the genome. Recent studies shed new light on the mechanistic action of these SMC machines and also expanded the repertoire of their diverse cellular functions. Dissecting this class of chromosomal ATPases is likely to be central to our understanding of the structural basis of genome organization, stability, and evolution.The chromosome is at the heart of all genetic processes. Its precise duplication and segregation are arguably the most important goal of the mitotic cell cycle, and programmed expression of its content, either genetic or epigenetic, is central to the development of an organism. While the astonishing advancement of genome biology in recent years has provided an advanced starting point for virtually all areas in biology, it does not solve an old problem in chromosome biology: How is the genomic DNA folded, organized, and segregated in the tiny space of a cell? The discovery of structural maintenance of chromosomes (SMC) proteins, almost a decade ago, provided a decisive clue to solve this longstanding question, and led to the identification of cohesin and condensins, two representative classes of SMC-containing complexes in eukaryotes. The proposed actions of cohesin and condensins offer a plausible, if not complete, explanation for the sudden appearance of thread-like "substances" (the chromosomes) and their longitudinal splitting during mitosis, first described by Walther Flemming (1882). Remarkably, SMC proteins are conserved among the three phyla of life, indicating that the basic strategy of chromosome organization may be evolutionarily conserved from bacteria to humans. An emerging theme is that SMC proteins are dynamic molecular linkers of the genome that actively fold, tether, and manipulate DNA strands. Their diverse functions range far beyond chromosome segregation, and involve nearly all aspects of chromosome behavior including chromosome-wide or long-range gene regulation and DNA repair. In this review article, we summarize our current understanding of SMC proteins with a major focus on studies published during the past three years. We start by describing the architecture and mechanistic actions of SMC protein complexes, and then discuss how the concerted actions of cohesin and condensin support the faithful segregation of chromosomes during mitosis and meiosis. Finally, emerging studies of a third S...

show abstract

“…In B. subtilis, segregation of the daughter strands appears to occur as replication proceeds [Webb et al, 1998]. For E. coli, the situation is less clear, as data obtained by FISH analysis suggest that the two sister chromosomes cohere for an extended period of time Sunako et al, 2001], while other studies on the localization of oriC in live cells suggest earlier segregation [Roos et al, 2001;Li et al, 2002;Lau et al, 2003]. …”

Section: Dynamics Of the Replication Processmentioning

confidence: 99%

The bacterial nucleoid: A highly organized and dynamic structure

Thanbichler

Wang

Shapiro

2005

J of Cellular Biochemistry

117

101

View full text Add to dashboard Cite

Recent advances in bacterial cell biology have revealed unanticipated structural and functional complexity, reminiscent of eukaryotic cells. Particular progress has been made in understanding the structure, replication, and segregation of the bacterial chromosome. It emerged that multiple mechanisms cooperate to establish a dynamic assembly of supercoiled domains, which are stacked in consecutive order to adopt a defined higher-level organization. The position of genetic loci on the chromosome is thereby linearly correlated with their position in the cell. SMC complexes and histone-like proteins continuously remodel the nucleoid to reconcile chromatin compaction with DNA replication and gene regulation. Moreover, active transport processes ensure the efficient segregation of sister chromosomes and the faithful restoration of nucleoid organization while DNA replication and condensation are in progress.

show abstract

Sister chromosome cohesion of Escherichia coli

Cited by 122 publications

References 32 publications

Mutants Suppressing Novobiocin Hypersensitivity of amukBNull Mutation

Mutants Suppressing Novobiocin Hypersensitivity of amukBNull Mutation

Dynamic molecular linkers of the genome: the first decade of SMC proteins

The bacterial nucleoid: A highly organized and dynamic structure

Contact Info

Product

Resources

About