Unfolded Proteins

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.

The word revolution has a number of definitions (The American Heritage Dictionary, 2006). The one most pertinent to this series and volume is 'a sudden or momentous change in a situation'. Recent years have seen an unprecedented explosion of interest in unfolded proteins in all of their various forms. Coupled with this increase in interest we have seen momentous changes in the way unfolded proteins are viewed. Two particular paradigms have come under close scrutiny: unfolded proteins are disordered random coils devoid of persistent structure, and protein function first requires protein structure. The first of these is currently a hotly debated subject. The second paradigm we can safely claim has been overturned. There is a second definition of revolution that is quite relevant to a significant portion of the work reviewed herein, in particular those chapters dealing with local and persistent structure in unfolded proteins. That definition is 'a turning or rotational motion about an axis' (The American Heritage Dictionary, 2006). About four decades ago, Charles Tanford (1968) demonstrated that highly denatured proteins possess hydrodynamic properties consistent with Paul Flory's random coil (Flory, 1969). Given that the Flory random coil definition included the stipulation that conformers making up the denatured state ensemble would differ in energy by just a few kT, there has been the assumption that denatured states must therefore be completely random in nature with no persistent structure or biases towards particular conformers. Notably however, Tanford did note the random coil-like hydrodynamic data he obtained did not necessarily rule out the presence of structure in denatured proteins (Tanford, 1968). Around the same time, Sam Krimm and M. Lois Tiffany noted that the CD spectra they obtained for proteins in the presence of high concentration of chemical denaturants had similarities to spectra obtained for homopolymers of proline, lysine, and glutamic acid in water (Tiffany and Krimm, 1968a, 1968b, 1973, 1974). Homopolymers of these residues were known to adopt the left-handed polyproline II conformation, leading Tiffany and Krimm to hypothesise that highly denatured proteins possess significant polyproline II helix content. Of these two views, that espousing the lack of structure in denatured proteins became more widely adopted and was, over time, adopted as a central paradigm in protein folding. As several of the chapters in this volume note, a Tiffany and Krimm-like view appears to be, to some extent, the more correct one. The level to which it is correct is still unknown, although it is clear that the polyproline II helical conformation is not the only, perhaps not even the most common, persistent conformation present in unfolded proteins. Thus we have come through a full circle or revolution. (from the preface)

A variety of complementary techniques and approaches have been used to characterize peptide and protein unfolding induced by temperature, pressure, and solvent. Volume 62, Unfolded Proteins, assembles these complementary views to develop a more complete picture of denatured peptides and proteins. The unifying observation common to all chapters is the detection of preferred backbone confirmations in experimentally accessible unfolded states. Peptide and protein unfolding induced by temperature, pressure, and solvent Denatured peptides and proteins Detection of preferred backbone confirmations in experimentally accessible unfolded states

Instrumental techniques for analyzing intrinsically disordered proteins The recently recognized phenomenon of protein intrinsic disorder is gaining significant interest among researchers, especially as the number of proteins and protein domains that have been shown to be intrinsically disordered rapidly grows. The first reference to tackle this little-documented area, Instrumental Analysis of Intrinsically Disordered Proteins: Assessing Structure and Conformation provides researchers with a much-needed, comprehensive summary of recent achievements in the methods for structural characterization of intrinsically disordered proteins (IDPs). Chapters discuss: Assessment of IDPs in the living cell Spectroscopic techniques for the analysis of IDPs, including NMR and EPR spectroscopies, FTIR, circular dichroism, fluorescence spectroscopy, vibrational methods, and single-molecule analysis Single-molecule techniques applied to the study of IDPs Assessment of IDP size and shape Tools for the analysis of IDP conformational stability Mass spectrometry Approaches for expression and purification of IDPs With contributions from an international selection of leading researchers, Instrumental Analysis of Intrinsically Disordered Proteins: Assessing Structure and Conformation fills an important need in a rapidly growing field. It is required reading for biochemists, biophysicists, molecular biologists, geneticists, cell biologists, physiologists, and specialists in drug design and development, proteomics, and molecular medicine with an interest in proteins and peptides.

This book discusses the paradigm-shifting phenomenon of intrinsically disordered proteins (IDPs) and hybrid proteins containing ordered domains and functional IDP regions (IDPRs). The properties of IDPs and IDPRs are highly complementary to those deriving from the presence of a unique and well-defined three-dimensional fold. Ignored for a long time in high-resolution studies of proteins, intrinsic protein disorder is now recognized as one of the key features for a large variety of cellular functions, where structural flexibility presents a functional advantage in terms of binding plasticity and promiscuity and this volume explores this exciting new research. Recent progress in the field has radically changed our perspective to study IDPs through NMR: increasingly complex IDPs can now be characterized, a wide range of observables can be determined reporting on the structural and dynamic properties, computational methods to describe the structure and dynamics are in continuous development and IDPs can be studied in environments as complex as whole cells. This volume communicates the new exciting possibilities offered by NMR and presents open questions to foster further developments. Intrinsically Disordered Proteins Studied by NMR Spectroscopy provides a snapshot to researchers entering the field as well as providing a current overview for more experienced scientists in related areas.

Intrinsically Disordered Proteins: Dynamics, Binding, and Function thoroughly examines and ties together the fundamental biochemical functions of intrinsically disordered proteins (IDPs) and intrinsically disordered regions (IDRs), including signaling, binding, and regulation, with the methodology for study and the associated pathways for drug design and therapeutic intervention. The role of new mechanistic, computational, and experimental approaches in IDP study are explored in depth, with methods for the characterization of IDP dynamics; models, simulations, and mechanisms of IDP and IDR binding; and biological and medical implications of IDP dynamics prominently featured. Written and edited by leading scientists in the field, this book explores groundbreaking areas such as ensemble descriptions of IDPs and IDRs, single-molecule studies of IDPs and IDRs, IDPs and IDRs in membraneless organelles, and molecular mechanisms of fibrillation of IDPs. Intrinsically Disordered Proteins provides students and researchers in biochemistry, molecular biology, and applied microbiology with a comprehensive and updated discussion of the complex dynamics of IDPs and IDRs. Provides in-depth discussion of fundamental IDP and IDR dynamics, function, and binding, with mechanistic insight to support new drug development Describes the role of new computational and experimental approaches in characterizing the binding of IDPs to their functional targets Features chapter contributions from international experts in IDP and IDR biochemical function and methods of study

Provides an introduction to the structure and function of biomolecules --- especially proteins --- and the physical tools used to investigate them The discussion concentrates on physical tools and properties, emphasizing techniques that are contributing to new developments and avoiding those that are already well established and whose results have already been exploited fully New tools appear regularly - synchrotron radiation, proton radiology, holography, optical tweezers, and muon radiography, for example, have all been used to open new areas of understanding