Dataset Information

Static and Dynamic Factors Limit Chromosomal Replication Complexity in Escherichia coli, Avoiding Dangers of Runaway Overreplication.

ABSTRACT: We define chromosomal replication complexity (CRC) as the ratio of the copy number of the most replicated regions to that of unreplicated regions on the same chromosome. Although a typical CRC of eukaryotic or bacterial chromosomes is 2, rapidly growing Escherichia coli cells induce an extra round of replication in their chromosomes (CRC = 4). There are also E. coli mutants with stable CRC?6. We have investigated the limits and consequences of elevated CRC in E. coli and found three limits: the "natural" CRC limit of ?8 (cells divide more slowly); the "functional" CRC limit of ?22 (cells divide extremely slowly); and the "tolerance" CRC limit of ?64 (cells stop dividing). While the natural limit is likely maintained by the eclipse system spacing replication initiations, the functional limit might reflect the capacity of the chromosome segregation system, rather than dedicated mechanisms, and the tolerance limit may result from titration of limiting replication factors. Whereas recombinational repair is beneficial for cells at the natural and functional CRC limits, we show that it becomes detrimental at the tolerance CRC limit, suggesting recombinational misrepair during the runaway overreplication and giving a rationale for avoidance of the latter.

SUBMITTER: Khan SR

PROVIDER: S-EPMC4788131 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature

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Static and Dynamic Factors Limit Chromosomal Replication Complexity in Escherichia coli, Avoiding Dangers of Runaway Overreplication.

Khan Sharik R SR Mahaseth Tulip T Kouzminova Elena A EA Cronan Glen E GE Kuzminov Andrei A

Genetics 20160122 3

We define chromosomal replication complexity (CRC) as the ratio of the copy number of the most replicated regions to that of unreplicated regions on the same chromosome. Although a typical CRC of eukaryotic or bacterial chromosomes is 2, rapidly growing Escherichia coli cells induce an extra round of replication in their chromosomes (CRC = 4). There are also E. coli mutants with stable CRC∼6. We have investigated the limits and consequences of elevated CRC in E. coli and found three limits: the ...[more]

PMID: 26801182

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Project description:The recent discovery of multiple giant double-stranded DNA (dsDNA) viruses blurred the consensual distinction between viruses and cells due to their size, as well as to their structural and genetic complexity. A dramatic feature revealed by these viruses as well as by many positive-strand RNA viruses is their ability to rapidly form elaborate intracellular organelles, termed "viral factories," where viral progeny are continuously generated. Here we report the first isolation of viral factories at progressive postinfection time points. The isolated factories were subjected to mass spectrometry-based proteomics, bioinformatics, and imaging analyses. These analyses revealed that numerous viral proteins are present in the factories but not in mature virions, thus implying that multiple and diverse proteins are required to promote the efficiency of viral factories as "production lines" of viral progeny. Moreover, our results highlight the dynamic and highly complex nature of viral factories, provide new and general insights into viral infection, and substantiate the intriguing notion that viral factories may represent the living state of viruses. IMPORTANCE Large dsDNA viruses such as vaccinia virus and the giant mimivirus, as well as many positive-strand RNA viruses, generate elaborate cytoplasmic organelles in which the multiple and diverse transactions required for viral replication and assembly occur. These organelles, which were termed "viral factories," are attracting much interest due to the increasing realization that the rapid and continuous production of viral progeny is a direct outcome of the elaborate structure and composition of the factories, which act as efficient production lines. To get new insights into the nature and function of viral factories, we devised a method that allows, for the first time, the isolation of these organelles. Analyses of the isolated factories generated at different times postinfection by mass spectrometry-based proteomics provide new perceptions of their role and reveal the highly dynamic nature of these organelles.

Dataset Information

Static and Dynamic Factors Limit Chromosomal Replication Complexity in Escherichia coli, Avoiding Dangers of Runaway Overreplication.

Publications

Static and Dynamic Factors Limit Chromosomal Replication Complexity in Escherichia coli, Avoiding Dangers of Runaway Overreplication.

Similar Datasets

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