Balance and coordination between cell growth and DNA replication in distantly related bacteria
Abstract/Contents
- Abstract
- Cell growth and DNA replication are ubiquitous processes of all cellular life. Model bacteria, being genetically tractable and relatively simple to work with, provide excellent systems to investigate cellular growth. Yet, bacterial life is also highly diverse, allowing us to examine a wide variety of questions about how cells grow and proliferate. In this work, we leverage this natural variability to ask two very different questions about cell growth and its relationship to DNA replication. Chapter 2 addresses the question, what are the origins of the fundamental limits of cell growth? We employ the popular model organism Escherichia coli to interrogate the assumption that ribosomes serve as the sole bottleneck of growth rate in bacteria. Using timelapse microscopy of filamenting strains, as well as single molecule tracking of the molecular machines RNA polymerase (RNAP) and ribosomes, this project shows that when genome concentration is diluted by cell growth, growth quickly exits the exponential regime and reaches a plateau. As the genome is diluted, the fraction of active RNAPs and ribosomes decreases, presumably as a result of decreased mRNA concentration. Thus, this project demonstrates that DNA concentration quickly becomes limiting for the attainable cell growth rate, and does so within the physiologic cell size range. This work proposes that bacteria live at the cusp of DNA limitation, a bottleneck of cell growth not previously appreciated. Our findings highlight the economical nature of bacteria and emphasize the importance of initiating DNA replication at a particular mass per origin of replication. Chapter 3 poses the question, how does a bacterium with an unusually complex life cycle grow? Using modified timelapse microscopy techniques, this work shows that the functionally different daughter cells that result from the asymmetric division of the ɑ-proteobacterium Caulobacter crescentus grow at different rates that are associated with the amount of time cells spend in the pre-DNA replication (G1) phase. By following the cell cycle localization of the well-described DNA replication-associated protein MipZ, this project identifies a connection between growth rate and DNA replication not previously appreciated in this bacterium: a requisite increase in cell size that must be added between cell birth and DNA replication initiation, referred to here as the "G1 adder". We speculate on the utility of the G1 adder as a means to integrate growth rate, cell size, and cell cycle progression with the functionality of the G1 phase specific to this bacterium. Finally, this project begins probing the source of the cell cycle correlated growth rate change and proposes areas of future study. Together, these studies represent the questions, from the broad and universal to the fascinatingly specific, that can be examined using bacteria as models of cell growth.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2023; ©2023 |
| Publication date | 2023; 2023 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Glenn, Judith Skye |
|---|---|
| Degree supervisor | Jacobs-Wagner, Christine |
| Thesis advisor | Jacobs-Wagner, Christine |
| Thesis advisor | Cremer, Jonas |
| Thesis advisor | Huang, Kerwyn Casey, 1979- |
| Thesis advisor | Shapiro, Lucy |
| Degree committee member | Cremer, Jonas |
| Degree committee member | Huang, Kerwyn Casey, 1979- |
| Degree committee member | Shapiro, Lucy |
| Associated with | Stanford University, School of Humanities and Sciences |
| Associated with | Stanford University, Department of Biology |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Judith Skye Glenn. |
|---|---|
| Note | Submitted to the Department of Biology. |
| Thesis | Thesis Ph.D. Stanford University 2023. |
| Location | https://purl.stanford.edu/vw705cz0962 |
Access conditions
- Copyright
- © 2023 by Judith Skye Glenn
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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