Investigating the Genetic Linkage Between Chromosomal Replication and Cell Division in Caulobacter Crescentus
Investigating the Genetic Linkage Between Chromosomal Replication and Cell Division in Caulobacter Crescentus

Author: Duha AlAwad

Publisher:

Published: 2022

Total Pages: 0

ISBN-13:

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"Caulobacter crescentus is a well-established model for studying the bacterial cell cycle, a complex process where the stages of growth, chromosome replication, and cell division often overlap, highlighting the presence of a highly coordinated regulatory network that remains partially understood. To search for novel regulators of the cell cycle, specifically of chromosomal replication, we developed a novel molecular screen to isolate dipM-like mutants. DipM is an endopeptidase and a cell division protein that was implicated in the coordination of DNA replication and cell division by our group. We believe that by generating Caulobacter mutants and selecting dipM-like phenotypes, it is possible to target defects in the pathway that regulate the progression from chromosomal replication to cell wall division, where DipM seems to be a key player. Out of nearly a hundred mutants, three dipM-like mutants were selected for genome sequencing, MUT1, MUT2, and MUT3. Bioinformatics analysis of these mutants allowed the identification of six gene candidates that could be linked to the regulation of the bacterial cell cycle, specifically chromosomal replication. We further investigated MUT1 and MUT3 by complementing them with the wildtype (WT) counterparts of the mutated genes to test for WT phenotype restoration. Our findings suggest that the identified gene candidates contribute to the cell cycle progression, specifically to chromosomal replication, by maintaining protein homeostasis. We speculate that DipM works with other regulatory proteins to sense and react to disturbances in protein homeostasis. Overall, our findings provide evidence for the effectiveness of our genetic screening technique and its capacity to detect cell cycle regulators coordinating between chromosome replication and cell wall division"--

DipM, a Potential Replication and Polar-organizing Protein in "Caulobacter Crescentus"
DipM, a Potential Replication and Polar-organizing Protein in

Author: Priya Patel

Publisher:

Published: 2020

Total Pages:

ISBN-13:

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"When screening for novel replication control genes in C. crescentus, we unexpectedly identified a temperature sensitive (TS) allele of the cell division-related gene dipM. In the published literature, DipM has been identified as a non-canonical endopeptidase that aids in peptidoglycan cell remodelling, particularly at the cell division septum. To confirm DipM’s unexpected relationship to DNA replication, we studied plasmid replication. We show that intact chromosomal dipM is required to support autonomous replication of four different replicon-types. A potential defect in replication prompted us to investigate fluorescently-tagged ParB of the chromosome partitioning system to report on Cori replication. While we observe multiple ParB foci within filamentous ∆dipM cells, this analysis does not unambiguously separate the cell division and replication defects. The number of ParB foci per cell length is very similar in both WT and [Delta]dipM cells, indicating that [Delta]dipM cells do not significantly over-initiate or under-initiate chromosome replication. Additionally, we investigated fluorescently-tagged DnaN of the replisome complex to report on active replication. Here we demonstrate that ∆dipM cells contain an insufficient number DnaN foci per cell length, potentially indicating impaired on-going replication. Moreover, our work reveals a synergistic interaction between ∆dipM and ParB-GFP and between ∆dipM and DnaN-eYFP, suggesting that cryptic replication defects of these fusion proteins are normally suppressed by DipM. Since studies report polarity-related issues in ∆dipM cells and chromosome replication relies on polarity cues, we assessed cellular polarity based on polar localization of ParB. We find ParB can localize normally to cell poles, albeit in a unique configuration within ∆dipM cells. Our data also shows that DipM does not affect ParB-chromosome anchoring or the depth of pole-organizing protein PopZ. Notably, we report polar malfunction in ∆dipM cells where we suspect mislocalization of an efflux pump causes Nal-induced toxicity. This explanation is derived from work of an independent research group who first discovered an unexpected link between polarity factor TipN and efflux-pump mediated toxicity. On this account, we implicate DipM as a potential polarity factor. Ultimately, we want to understand the relationship between DipM, chromosome replication and cell polarity. Based on these lines of evidence, we hypothesize that DipM is involved in chromosome replication by influencing polar organization"--

Prokaryotic Cytoskeletons
Prokaryotic Cytoskeletons

Author: Jan Löwe

Publisher: Springer

Published: 2017-05-11

Total Pages: 457

ISBN-13: 331953047X

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This book describes the structures and functions of active protein filaments, found in bacteria and archaea, and now known to perform crucial roles in cell division and intra-cellular motility, as well as being essential for controlling cell shape and growth. These roles are possible because the cytoskeletal and cytomotive filaments provide long range order from small subunits. Studies of these filaments are therefore of central importance to understanding prokaryotic cell biology. The wide variation in subunit and polymer structure and its relationship with the range of functions also provide important insights into cell evolution, including the emergence of eukaryotic cells. Individual chapters, written by leading researchers, review the great advances made in the past 20-25 years, and still ongoing, to discover the architectures, dynamics and roles of filaments found in relevant model organisms. Others describe one of the families of dynamic filaments found in many species. The most common types of filament are deeply related to eukaryotic cytoskeletal proteins, notably actin and tubulin that polymerise and depolymerise under the control of nucleotide hydrolysis. Related systems are found to perform a variety of roles, depending on the organisms. Surprisingly, prokaryotes all lack the molecular motors associated with eukaryotic F-actin and microtubules. Archaea, but not bacteria, also have active filaments related to the eukaryotic ESCRT system. Non-dynamic fibres, including intermediate filament-like structures, are known to occur in some bacteria.. Details of known filament structures are discussed and related to what has been established about their molecular mechanisms, including current controversies. The final chapter covers the use of some of these dynamic filaments in Systems Biology research. The level of information in all chapters is suitable both for active researchers and for advanced students in courses involving bacterial or archaeal physiology, molecular microbiology, structural cell biology, molecular motility or evolution. Chapter 3 of this book is open access under a CC BY 4.0 license.

Size Limits of Very Small Microorganisms
Size Limits of Very Small Microorganisms

Author: National Research Council

Publisher: National Academies Press

Published: 1999-10-13

Total Pages: 171

ISBN-13: 0309066344

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How small can a free-living organism be? On the surface, this question is straightforward-in principle, the smallest cells can be identified and measured. But understanding what factors determine this lower limit, and addressing the host of other questions that follow on from this knowledge, require a fundamental understanding of the chemistry and ecology of cellular life. The recent report of evidence for life in a martian meteorite and the prospect of searching for biological signatures in intelligently chosen samples from Mars and elsewhere bring a new immediacy to such questions. How do we recognize the morphological or chemical remnants of life in rocks deposited 4 billion years ago on another planet? Are the empirical limits on cell size identified by observation on Earth applicable to life wherever it may occur, or is minimum size a function of the particular chemistry of an individual planetary surface? These questions formed the focus of a workshop on the size limits of very small organisms, organized by the Steering .Group for the Workshop on Size Limits of Very Small Microorganisms and held on October 22 and 23, 1998. Eighteen invited panelists, representing fields ranging from cell biology and molecular genetics to paleontology and mineralogy, joined with an almost equal number of other participants in a wide-ranging exploration of minimum cell size and the challenge of interpreting micro- and nano-scale features of sedimentary rocks found on Earth or elsewhere in the solar system. This document contains the proceedings of that workshop. It includes position papers presented by the individual panelists, arranged by panel, along with a summary, for each of the four sessions, of extensive roundtable discussions that involved the panelists as well as other workshop participants.

Asymmetric Cell Division in Development, Differentiation and Cancer
Asymmetric Cell Division in Development, Differentiation and Cancer

Author: Jean-Pierre Tassan

Publisher: Springer

Published: 2017-04-12

Total Pages: 421

ISBN-13: 3319531506

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This book provides readers with an overview of the frequent occurrence of asymmetric cell division. Employing a broad range of examples, it highlights how this mode of cell division constitutes the basis of multicellular organism development and how its misregulation can lead to cancer. To underline such developmental correlations, readers will for example gain insights into stem cell fate and tumor growth. In turn, subsequent chapters include descriptions of asymmetric cell division from unicellular organisms to humans in both physiological and pathological conditions. The book also illustrates the importance of this process for evolution and our need to understand the background mechanisms, offering a valuable guide not only for students in the field of developmental biology but also for experienced researchers from neighboring fields.

Cell Cycle and Cell Differentiation
Cell Cycle and Cell Differentiation

Author: J. Reinert

Publisher: Springer Science & Business Media

Published: 2013-06-29

Total Pages: 336

ISBN-13: 354037390X

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It is instructive to compare the response of biologists to the two themes that comprise the title of this volume. The concept of the cell cycle-in contra distinction to cell division-is a relatively recent one. Nevertheless biologists of all persuasions appreciate and readily agree on the central problems in this area. Issues ranging from mechanisms that initiate and integrate the synthesis of chro mosomal proteins and DNA during S-phase of mitosis to the manner in which assembly of microtubules and their interactions lead to the segregation of metaphase chromosomes are readily followed by botanists and zoologists, as well as by cell and molecular biologists. These problems are crisp and well-defined. The current state of "cell differentiation" stands in sharp contrast. This, one of the oldest problems in experimental biology, almost defies definition today. The difficulties arise not only from a lack of pertinent information on the regulatory mechanisms, but also from conflicting basic concepts in this field. One of the ways in which this situation might be improved would be to find a broader experimental basis, including a better understanding of the relationship between the cell cycle and cell differentiation.

Histidine Kinases in Signal Transduction
Histidine Kinases in Signal Transduction

Author: Masayori Inouye

Publisher: Elsevier

Published: 2002-11-13

Total Pages: 539

ISBN-13: 0080534015

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Living cells are constantly sensing environmental changes, and their abilities to sense these changes and adapt to them are essential for their survival. In bacteria, histidine kinases are the major sensors for these environmental stresses, enabling cells to adapt to new growth conditions. Written by leading experts in the field, this book provides an up-to-date and comprehensive review on the structure and function of histidine kinases. It also provides extensive information on the physiological roles of histidine kinases in bacteria and eukaryotes. An an essential reference for cell biologists, microbiologists, molecular biologists, and biochemists interested in signal transduction. Experimental biologists and pharmacologists studying signal transduction systems in living organisms will also find it a valuable research tool. The first comprehensive book on the roles of histidine kinases in cells 23 in-depth chapters written by leading experts in the field Describes the most recent advances in the field of signal transduction

Physical Biology of the Cell
Physical Biology of the Cell

Author: Rob Phillips

Publisher: Garland Science

Published: 2012-10-29

Total Pages: 1089

ISBN-13: 1134111584

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Physical Biology of the Cell is a textbook for a first course in physical biology or biophysics for undergraduate or graduate students. It maps the huge and complex landscape of cell and molecular biology from the distinct perspective of physical biology. As a key organizing principle, the proximity of topics is based on the physical concepts that

Prokaryotic Metabolism and Physiology
Prokaryotic Metabolism and Physiology

Author: Byung Hong Kim

Publisher: Cambridge University Press

Published: 2019-05-16

Total Pages: 509

ISBN-13: 1107171733

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Extensive and up-to-date review of key metabolic processes in bacteria and archaea and how metabolism is regulated under various conditions.