How bacteria control their shape and division was one of the first topics investigated with molecular biology, and many unanswered questions remain today. This dissertation research used the model organism Cualobacter crescentus to investigate how phospho-signaling controls asymmetric cell division, and how those signals are initiated and regulated. Most signaling in bacteria is achieved through two component systems (TCS), which are comprised of a histidine kinase and a response regulator. The downstream effects of response regulator activation have been well documented and can affect gene transcription, protein interactions or enzyme activity. However, very little is known about how histidine kinases are activated. Caulobacter uses TCS to control its asymmetric cell division and differentiation, but the events that initiate the cell cycle and the ability of an outside signal to impinge upon cell cycle progression remain unknown. Using three different methods, I have been able to shed light on signaling and cell cycle progression in Caulobacter crescentus. I have developed a tool to determine which proteins and conditions activate histidine kinases. I have shown that an outside environmental signal can feed into the TCS controlling cell cycle progression. I have also shown that a protein similar to a eukaryotic tyrosine phosphatase controls membrane integrity and morphology and is essential for viability in Caulobacter.
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.
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.
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.
Focusing on the systems biology of bacteria and microorganisms, the 39th volume of Methods in Microbiology investigates the interface between molecular biology, bioinformatics, and modelling and predicting behavior. This cutting-edge research area is of extreme importance to the field and is developing quickly.
This book covers allocation of metals in cells, metal transporter, storage and metalloregulatory proteins, cellular responses to metal ion stress, transcription of genes involved in metal ion homeostasis, uptake of essential metals, metal efflux and other detoxification mechanisms. The book also discusses metal bioreporters for the nanomolar range of concentration and tools to address the metallome. In addition, coverage details specific metals.
Bacteria in various habitats are subject to continuously changing environmental conditions, such as nutrient deprivation, heat and cold stress, UV radiation, oxidative stress, dessication, acid stress, nitrosative stress, cell envelope stress, heavy metal exposure, osmotic stress, and others. In order to survive, they have to respond to these conditions by adapting their physiology through sometimes drastic changes in gene expression. In addition they may adapt by changing their morphology, forming biofilms, fruiting bodies or spores, filaments, Viable But Not Culturable (VBNC) cells or moving away from stress compounds via chemotaxis. Changes in gene expression constitute the main component of the bacterial response to stress and environmental changes, and involve a myriad of different mechanisms, including (alternative) sigma factors, bi- or tri-component regulatory systems, small non-coding RNA’s, chaperones, CHRIS-Cas systems, DNA repair, toxin-antitoxin systems, the stringent response, efflux pumps, alarmones, and modulation of the cell envelope or membranes, to name a few. Many regulatory elements are conserved in different bacteria; however there are endless variations on the theme and novel elements of gene regulation in bacteria inhabiting particular environments are constantly being discovered. Especially in (pathogenic) bacteria colonizing the human body a plethora of bacterial responses to innate stresses such as pH, reactive nitrogen and oxygen species and antibiotic stress are being described. An attempt is made to not only cover model systems but give a broad overview of the stress-responsive regulatory systems in a variety of bacteria, including medically important bacteria, where elucidation of certain aspects of these systems could lead to treatment strategies of the pathogens. Many of the regulatory systems being uncovered are specific, but there is also considerable “cross-talk” between different circuits. Stress and Environmental Regulation of Gene Expression and Adaptation in Bacteria is a comprehensive two-volume work bringing together both review and original research articles on key topics in stress and environmental control of gene expression in bacteria. Volume One contains key overview chapters, as well as content on one/two/three component regulatory systems and stress responses, sigma factors and stress responses, small non-coding RNAs and stress responses, toxin-antitoxin systems and stress responses, stringent response to stress, responses to UV irradiation, SOS and double stranded systems repair systems and stress, adaptation to both oxidative and osmotic stress, and desiccation tolerance and drought stress. Volume Two covers heat shock responses, chaperonins and stress, cold shock responses, adaptation to acid stress, nitrosative stress, and envelope stress, as well as iron homeostasis, metal resistance, quorum sensing, chemotaxis and biofilm formation, and viable but not culturable (VBNC) cells. Covering the full breadth of current stress and environmental control of gene expression studies and expanding it towards future advances in the field, these two volumes are a one-stop reference for (non) medical molecular geneticists interested in gene regulation under stress.
International Review of Cell and Molecular Biology presents current advances and comprehensive reviews in cell biology--both plant and animal. Articles address structure and control of gene expression, nucleocytoplasmic interactions, control of cell development and differentiation, and cell transformation and growth. Impact factor for 2012: 4.973. Ideas from the fields of biophysics, physical chemistry, of polymer and colloid, and soft matter science have helped clarify the structure and functions of the cell nucleus. The development of powerful methods for modeling conformations and interactions of macromolecules has also contributed. The book aims to encourage cell and molecular biologists to become more familiar with and understand these new concepts and methods, and the crucial contributions they are making to our perception of the nucleus. This is the first volume to present a comprehensive review of New Models of the Cell Nucleus
Providing a comprehensive insight into cellular signaling processes in bacteria with a special focus on biotechnological implications, this is the first book to cover intercellular as well as intracellular signaling and its relevance for biofilm formation, host pathogen interactions, symbiotic relationships, and photo- and chemotaxis. In addition, it deals in detail with principal bacterial signaling mechanisms -- making this a valuable resource for all advanced students in microbiology. Dr. Krämer is a world-renowned expert in intracellular signaling and its implications for biotechnology processes, while Dr. Jung is an expert on intercellular signaling and its relevance for biomedicine and agriculture.
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.
