Functions And Mechanisms Of Bacterial Protein Homeostasis And Stress Responses

The Cover Image for This Research Topic is Used With Permission of the Authors and Publishers of the Following Article: Winkler J, Seybert A, König L, Pruggnaller S, Haselmann U, Sourjik V, Weiss M, Frangakis AS, Mogk A, Bukau B.EMBO J. 2010 Mar 3;29(5):910-23. doi: 10.1038/emboj.2009.412. Epub 2010 Jan 21

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.

This work is concerned with a group of proteins which were originally consid ered to be an esoteric phenomenon but which have now been shown to play critical roles both in normal and stressed cells as well as being involved in a variety of human diseases. It is the purpose of this work to give a comprehen sive view of these proteins and their various aspects. After an introductory chapter providing an overview of these proteins, the work is divided into four main sections each of which deals with one important aspect of these proteins. Thus, the first section contains a series of chapters which describe individual stress proteins and their roles in particular biological phenomena. Evidently, the induction of these proteins by elevated tempera ture or other stresses is their defining feature and the second section of this book therefore considers the regulation of stress protein gene expression both by stressful stimuli such as elevated temperature or ischaemia and by non stressful stimuli such as cytokines.

This book is the first comprehensive volume on the "Nramp family", highlighting the physiological importance of Nramp proteins as metal transporters. The molecular knowledge of these membrane proteins is presented from an evolutionary perspective, considering Nramp cellular function and mechanism of transport in key model organisms. The pathological significance of Nramp genetic polymorphism is discussed with emphasis on metal homeostasis and microbial infection. The chapters were contributed by leading investigators, providing a timely state of the art book in this rapidly growing field. The Nramp Family will be useful to a broad community of scientists interested in metal transport and molecular biology. It will be of interest to the research audience in the broad fields of metal ions and molecular medicine.

A critical factor for bacterial survival in any environment is the ability to sense and respond appropriately to insults that cause stress to the cell, threatening its survival. Most of these stressors first affect the outer surface of the bacterial cell, are sensed in some way, and defense measures are enacted in response. If the bacteria successfully respond to an encountered stress, they survive and multiply. If they are unsuccessful or inefficient in their response, it can result in death. Efficiently responding to factors that induce stress is especially important for bacteria that inhabit environments that are constantly changing, or for those that inhabit more than one biological niche. In addition, bacterial species that associate with humans and other organisms must be able to overcome stresses that are produced by the host immune response in order to colonize and cause disease. The wide variety of stressors encountered by bacteria has resulted in countless strategies that are used by pathogens to overcome these insults, which we continue to identify. Clearly, a better understanding of these stress response mechanisms may be useful for developing new strategies to combat bacteria that cause certain infectious diseases. This Research Topic aims to highlight our increasing understanding of mechanisms by which bacteria sense and respond to stresses encountered in the host or other environments. Examples of stress response mechanisms of interest include, but are not limited to those that respond to antimicrobials, host immune responses, or environmental changes.

Foodborne illness resulting from food production animals is a global health concern, and the Centers for Disease Control estimate that one in six Americans will become sick with a foodborne illness each year. Of course there are numerous causes for these outbreaks, but contamination from a food production animal is certainly one source. Understanding the host-pathogen interaction and how foodborne bacterial pathogens establish a persistent infection and evade host immune responses will be pivotal in reducing the instance of foodborne illness traced back to a food production animal source. In this volume, we bring together original research and review articles covering some of the key issues surrounding the mechanisms of persistence, survival, and transmission of bacterial foodborne pathogens in production animals. The research focused on poultry and specifically addressed antibiotic resistance, Salmonella colonization, pathogen reduction strategies using pre- or probiotics, pathogen evasion, and post-harvest intervention and pathogen testing. The following 11 articles are fine examples of the multidisciplinary approaches that will be required to address and understand the complex interplay between food safety and animal production.

This volume is divided in six section covering the most experimental approaches involved in the study of the unfolded protein response (UPR) pathway. Chapters detail determination of unfolded protein levels, methods to study UPR signal transmission, analysing the outcomes of the UPR pathway activation, UPR studies in mammalian models, UPR in alternative models, and UPR and disease. Written in the format of the highly successful Methods in Molecular Biology series, each chapter includes an introduction to the topic, lists necessary materials and reagents, includes tips on troubleshooting and known pitfalls, and step-by-step, readily reproducible protocols. Authoritative and cutting-edge, The Unfolded Protein Response: Methods and Protocols aims to describe key methods and approaches used in the study of the UPR pathway and its complex cellular implications. Chapter 6 is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.