Download or read book Chromosome Segregation and Structure in Caulobacter Crescentus written by Esteban Toro Gomez and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Chromosome Segregation and Structure written by Terri Grodzicker and published by Symposium Proceedings. This book was released on 2018-07-31 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 82nd Cold Spring Harbor Symposium focused on Chromosome Segregation & Structure and addressed the enormous progress in our understanding of the nature and behavior of chromosomes during the life cycle of the cell. It is rare to find such a wide-ranging perspective on this topic in one volume and this collection of papers will be valuable to investigators interested in many aspects of cell biology, genetics, and cancer. The topics covered at the meeting included: Meiosis; Mitosis; Chromosome Segregation; Centrosomes and Centrioles; Ploidy, Chromosome Segregation Errors & Disease; Asymmetric Cell Division; Nuclear Architecture; Chromosome Structure and Condensation; Sister Chromatid Cohesion; Genome Stability; and Germ Cells. Numerous speakers participated in interviews during the course of the Symposium week and transcripts of those discussions and the Dorcas Cummings lecture by David Page are included.
Download or read book A Quantitative Analysis of the Structure and Dynamics of the Bacterial Chromosome written by Sun-Hae Hong and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Replication and segregation of the chromosome in the bacterium Caulobacter crescentus takes place simultaneously. Although it is known that each arm of the circular chromosome is on average linearly positioned along the cell length, the detailed configuration of the DNA in the cell is not well understood. Furthermore, in replicating bacterial cells, the centromere is segregated by a ParA-dependent mechanism and anchored at the pole, but the segregation mechanism for the rest of the chromosome is not known. To address these questions, I tracked the position and motion of multiple chromosomal loci both in non-replicating and replicating cells. By characterizing compaction of the DNA in non-replicating cells, I show that the DNA in the Caulobacter cells has the mean end-to-end distance that scale as (contour length)0.22, which suggests that compaction of the bacterial DNA is primarily driven by supercoiling. Analysis of the replication/segregation dynamics revealed that Caulobacter chromosome segregation is bimodal: Centromere-proximal DNA is segregated with the centromere at a slow pace whereas the rest of the DNA is segregated much faster. The dynamics of the centromere-distal DNA are consistent with a model where continuous compaction pulls the DNA toward the pole. The results provide a new perspective on the physical configuration of the non-replicating DNA and on the movement and compaction of newly replicated DNA immediately after replication and during its transport from the replisome to the cell poles.
Download or read book The Dynamics and Regulation of Chromosome Segregation in Caulobacter Crescentus written by Conrad William Shebelut and published by . This book was released on 2010 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Prokaryotic Cytoskeletons written by Jan Löwe and published by Springer. This book was released on 2017-05-11 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Chromosome Structure and Function written by Rudi Appels and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Historical Perspective on the Study of Chromosome Structure and Function R. Appels Division of Plant Industry CSIRO P.O. Box 1600 A.C.T. AUSTRALIA "Modern physical science gives us no model to explain the re duplication of the gene-string in each cell generation, or to ex plain the production of effective quantities of specific enzymes or other agents by specific genes. The precise pairing and inter change of segments by homologous gene-strings at meiosis also suggest novel physical properties of this form of matter". Stadler (1954) The very strong influence of reductionism in the history of understanding chromosome structure and function is evident in the above quotation from Stadler's 1954 paper, "The gene". Earlyob servations on the constancy of the cytological appearance of chromo somes and their regular behaviour in cell division led to specula tion on their biological importance. As genetics became more refined in the early decades of the 20th century the genes-on-a string model of chromosomes developed and greater emphasis was placed on the further dissection of these structures. As a result, in the 1980's the reductionist approach is reaching a crest as extensive regions of the genetic material are being sequenced.
Download or read book Analysis of an Uncharacterized Gene in Caulobacter Crescentus and Its Novel Connections with Cell Cycle Regulatory Machinery written by Haibi Wang and published by . This book was released on 2019 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: Cell division and differentiation are complex biological phenomena that occur in all kingdoms of life. Understanding the molecular mechanisms that underlie these complex processes often requires the study of experimentally tractable model organisms. As a Gram-negative bacteria with less than four thousand genes, Caulobacter crescentus exhibits cell differentiation, highly regulated chromosome replication and segregation, and asymmetric cell division with every turn of the cell cycle. To achieve these behaviors, Caulobacter utilizes spatial control mechanisms such as sub-cellular compartmentalization and protein localization. The cell poles are particularly enriched for cell cycle regulatory proteins. Many of these proteins are localized by the hub protein PopZ, which forms a three-dimensional scaffold that also aids in chromosome segregation. The PopZ scaffold also includes proteolysis activity, which regulates cell cycle progression in a manner that is analogous to well-known eukaryotic systems. In this dissertation, I characterized an evolutionarily conserved protein of unknown function, which is now named SpbR (Swarmer pole blocking factoR). SpbR is a pole-localized protein that has co-evolved with PopZ and other polar proteins. Strikingly, SpbR over-production exhibited a severe chromosome segregation phenotype, in which the newly replicated centromere failed to travel across the cell to its normal destination at the opposite pole. SpbR overproduction results in its accumulation at the old pole, where it physically interacts with PopZ. This prevents the relocation of PopZ to the new pole, thereby eliminating a positional cue for centromere translocation. Consistent with this, the centromere translocation phenotype of SpbR overproducing cells is further enhanced in genetic backgrounds that accumulate higher SpbR or reduce chromosome segregation activity. We find that pole-localized SpbR is normally cleared by proteolysis before the time of chromosome segregation, indicating that SpbR turnover is part of the cell cycle-dependent program of polar development.
Download or read book Size Limits of Very Small Microorganisms written by National Research Council and published by National Academies Press. This book was released on 1999-10-13 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Structure and Function of the Bacterial Genome written by Charles J. Dorman and published by John Wiley & Sons. This book was released on 2020-02-04 with total page 545 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents an integrated view of the expression of bacterial genetic information, genome architecture and function, and bacterial physiology and pathogenesis This book blends information from the very latest research on bacterial chromosome and nucleoid architecture, whole-genome analysis, cell signaling, and gene expression control with well-known gene regulation paradigms from model organisms (including pathogens) to give readers a picture of how information flows from the environment to the gene, modulating its expression and influencing the competitive fitness of the microbe. Structure and Function of the Bacterial Genome explores the governance of the expression of the genes that make a bacterium what it is, and updates the basics of gene expression control with information about transcription promoter structure and function, the role of DNA as a regulatory factor (in addition to its role as a carrier of genetic information), small RNAs, RNAs that sense chemical signals, ribosomes and translation, posttranslational modification of proteins, and protein secretion. It looks at the forces driving the conservation and the evolution of the dynamic genome and offers chapters that cover DNA replication, DNA repair, plasmid biology, recombination, transposition, the roles of repetitive DNA sequences, horizontal gene transfer, the defense of the genome by CRISPR-Cas, restriction enzymes, Argonaute proteins and BREX systems. The book finishes with a chapter that gives an integrated overview of genome structure and function. Blends knowledge of gene regulatory mechanisms with a consideration of nucleoid structure and dynamics Offers a 'DNA-centric' approach to considering transcription control Views horizontal gene transfer from a gene regulation perspective Assesses the opportunities and limitations of designing synthetic microbes or rewiring existing ones Structure and Function of the Bacterial Genome is an ideal book for graduate and undergraduate students studying microbial cell biology, bacterial pathogenesis, gene regulation, and molecular microbiology. It will also appeal to principal investigators conducting research on these and related topics and researchers in synthetic biology and other arms of biotechnology.
Download or read book The Major Transitions in Evolution written by John Maynard Smith and published by Oxford University Press. This book was released on 1997-10-30 with total page 361 pages. Available in PDF, EPUB and Kindle. Book excerpt: During evolution there have been several major changes in the way genetic information is organized and transmitted from one generation to the next. These transitions include the origin of life itself, the first eukaryotic cells, reproduction by sexual means, the appearance of multicellular plants and animals, the emergence of cooperation and of animal societies. This is the first book to discuss all these major transitions and their implications for our understanding of evolution.Clearly written and illustrated with many original diagrams, this book will be welcomed by students and researchers in the fields of evolutionary biology, ecology, and genetics.
Download or read book Organization of the Prokaryotic Genome written by Robert L. Charlebois and published by . This book was released on 1999 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Two component Signal Transduction written by James A. Hoch and published by Amer Society for Microbiology. This book was released on 1995 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: The human enteroviruses, particularly the polio viruses, have had a significant role in the history of medicine and microbiology; and continue to cause clinical problems, as well as provide targets for molecular investigation. This book offers a link between the basic science and clinical medicine.
Download or read book Bacterial Physiology written by Walid El-Sharoud and published by Springer Science & Business Media. This book was released on 2007-12-07 with total page 377 pages. Available in PDF, EPUB and Kindle. Book excerpt: The application of new molecular methodologies in the study of bacterial behavior and cell architecture has enabled new revolutionary insights and discoveries in these areas. This new text presents recent developments in bacterial physiology that are highly relevant to a wide range of readership including those interested in basic and applied knowledge. Its chapters are written by international scientific authorities at the forefront of the subject. The value of this recent knowledge in bacterial physiology is not only restricted to fundamental biology. It also extends to biotechnology and drug-discovery disciplines.
Download or read book Bacterial Growth and Division written by Stephen Cooper and published by Elsevier. This book was released on 2012-12-02 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: How does a bacterial cell grow during the division cycle? This question is answered by the codeveloper of the Cooper-Helmstetter model of DNA replication. In a unique analysis of the bacterial division cycle, Cooper considers the major cell categories (cytoplasm, DNA, and cell surface) and presents a lucid description of bacterial growth during the division cycle. The concepts of bacterial physiology from Ole Maaløe's Copenhagen school are presented throughout the book and are applied to such topics as the origin of variability, the pattern of DNA segregation, and the principles underlying growth transitions. The results of research on E. coli are used to explain the division cycles of Caulobacter, Bacilli, Streptococci, and eukaryotes. Insightful reanalysis highlights significant similarities between these cells and E.coli. With over 25 years of experience in the study of the bacterial division cycle, Cooper has synthesized his ideas and research into an exciting presentation. He manages to write a comprehensive volume that will be of great interest to microbiologists, cell physiologists, cell and molecular biologists, researchers in cell-cycle studies, and mathematicians and engineering scientists interested in modeling cell growth. - Written by one of the codiscoverers of the Cooper-Helmstetter model - Applies the results of research on E. coli to other groups, including Caulobacter, Bacilli, Streptococci, and eukaryotes; the Caulobacter reanalysis highlights significant similarities with the E. coli system - Presents a unified description of the bacterial division cycle with relevance to eukaryotic systems - Addresses the concepts of the Copenhagen School in a new and original way
Download or read book Physical Biology of the Cell written by Rob Phillips and published by Garland Science. This book was released on 2012-10-29 with total page 1089 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Download or read book Lasso Peptides written by Yanyan Li and published by Springer. This book was released on 2014-10-21 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lasso peptides form a growing family of fascinating ribosomally-synthesized and post-translationally modified peptides produced by bacteria. They contain 15 to 24 residues and share a unique interlocked topology that involves an N-terminal 7 to 9-residue macrolactam ring where the C-terminal tail is threaded and irreversibly trapped. The ring results from the condensation of the N-terminal amino group with a side-chain carboxylate of a glutamate at position 8 or 9, or an aspartate at position 7, 8 or 9. The trapping of the tail involves bulky amino acids located in the tail below and above the ring and/or disulfide bridges connecting the ring and the tail. Lasso peptides are subdivided into three subtypes depending on the absence (class II) or presence of one (class III) or two (class I) disulfide bridges. The lasso topology results in highly compact structures that give to lasso peptides an extraordinary stability towards both protease degradation and denaturing conditions. Lasso peptides are generally receptor antagonists, enzyme inhibitors and/or antibacterial or antiviral (anti-HIV) agents. The lasso scaffold and the associated biological activities shown by lasso peptides on different key targets make them promising molecules with high therapeutic potential. Their application in drug design has been exemplified by the development of an integrin antagonist based on a lasso peptide scaffold. The biosynthesis machinery of lasso peptides is therefore of high biotechnological interest, especially since such highly compact and stable structures have to date revealed inaccessible by peptide synthesis. Lasso peptides are produced from a linear precursor LasA, which undergoes a maturation process involving several steps, in particular cleavage of the leader peptide and cyclization. The post-translational modifications are ensured by a dedicated enzymatic machinery, which is composed of an ATP-dependent cysteine protease (LasB) and a lactam synthetase (LasC) that form an enzymatic complex called lasso synthetase. Microcin J25, produced by Escherichia coli AY25, is the archetype of lasso peptides and the most extensively studied. To date only around forty lasso peptides have been isolated, but genome mining approaches have revealed that they are widely distributed among Proteobacteria and Actinobacteria, particularly in Streptomyces, making available a rich resource of novel lasso peptides and enzyme machineries towards lasso topologies.
Download or read book Cell Biology of Bacteria written by Lucy Shapiro and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Often thought to lack signifucant internal organization by comparison with eukaryotic cells, prokaryotes have in face been shown to possess distinct intracellular compartments. The book covers all aspects of prokaryotic cell biology, including the bacterial cytoskeleton, membrance organization, chromosome dynamics, nucleic acid processing and dynamics, as well as various methods.
