Chromosome segregation and structure in Caulobacter crescentus
Abstract/Contents
- Abstract
- Bacterial chromosomes are generally ~1000 times longer than the cells in which they reside, and concurrent replication, segregation, and transcription/translation of this crowded mass of DNA poses a challenging organizational problem. At first, it was assumed that DNA is organized randomly inside the cell, much like a bowl of spaghetti. Furthermore, it was argued that segregation of this disordered mass was not carried out by a mitotic machinery as is found in eukaryotes, but rather the by-product of cell growth. Hence, the canonical description of bacterial DNA was that of an unstructured polymer diffusing randomly. Recent advances in cell imaging technology, however, have revealed that the bacterial nucleoid is reliably oriented and highly organized within the cell. Furthermore, the speed of segregation is inconsistent with the old model driven by cell growth. Here, I use a screening approach to identify parS, a 100bp piece of DNA previously found to be anchored to the old cell pole, as the Caulobacter centromere. In direct contrast to other published models, parS segregates ahead of all other sequences, including the origin of replication (Cori), and moving parS away from Cori causes segregation -- but not replication -- to be delayed. The segregation of parS requires the ATPase activity of the ParA protein, and current work is aimed at understanding the molecular details of this process. All of these data point to the presence of an active, mitotic-like machine that drives chromosome segregation in Caulobacter. I also show that the circular Caulobacter chromosome is oriented in relation to the parS anchor site at the old cell pole, so that changing the genomic position of parS causes the entire chromosome to rotate within the cell. Finally, I find that the chromosome is organized into a dense core running down the length of the cell, and I arrive at two possible models for the large-scale structure of this core. Thus, this work forms part of an emerging view of the chromosome as a highly organized structure that is kept in place by simple yet active mechanisms, and whose segregation is insured by a complex dedicated machine.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2010 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Toro Gomez, Esteban |
|---|---|
| Associated with | Stanford University, Department of Developmental Biology. |
| Primary advisor | Shapiro, Lucy |
| Thesis advisor | Shapiro, Lucy |
| Thesis advisor | Burkholder, William |
| Thesis advisor | Kingsley, David M. (David Mark) |
| Thesis advisor | Villeneuve, Anne, 1959- |
| Advisor | Burkholder, William |
| Advisor | Kingsley, David M. (David Mark) |
| Advisor | Villeneuve, Anne, 1959- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Esteban Toro Gomez. |
|---|---|
| Note | Submitted to the Department of Developmental Biology. |
| Thesis | Ph. D. Stanford University 2010 |
| Location | electronic resource |
Access conditions
- Copyright
- © 2010 by Esteban Toro Gomez
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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