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.

PrefaceContributors1 Histidine Kinases: Introductory Remarks Introduction Basic Structure of Histidine Kinases (HKs) Uniqueness of HKs Difference between HKs and Ser/Thr/Tyr Kinases Signal Transduction Mechanism Regulation of Kinase and Phosphatase Activities: Switch Model and Rheostat Model Concluding Remarks References2 The Histidine Kinase Family: Structures of Essential Building Blocks Introduction Kinase/Phosphatase Core Domain Phosphotransfer Domain Considerations on Domain Interactions Concluding Remarks References3 Regulation of Porins in Escherichia coli by the Osmosensing Histidine Kinase~hosphatase EnvZ Introduction Domain A Is the Catalytic Domain Domain B Is the Catalysis-Assisting and ATP-Binding Domain Monomeric Histidine Kinase: Topological Arrangement between Domain A and Domain B Role of DNA in EnvZ Function Stoichiometric Complex Formation between EnvZ and OmpR Regulation of Kinase and Phosphatase Activities: Switch Model versus Rheostat Model Mechanism of Osmoregulation Concluding Remarks References4 Structure and Function of CheA, the Histidine Kinase Central to Bacterial Chemotaxis Introduction Modular Structure of CheA A Superfamily of Histidine Kinases and ATPases Nucleotide Binding by CheA P4 and the GHL ATPases ATP Hydrolysis and Conformation of P4 HPt Domain P1 and Phosphoryl Transfer P2 Domain and Response Regulator Coupling A Separate Dimerization Domain Receptor Coupling by the P5 Regulatory Domain Is Flexibility between Domains Important for Signaling? Controlling Protein-Protein Interactions with ATP Prospects for the Design of Antibiotics Directed at CheA What Is Next? References5 Transmembrane Signaling and the Regulation of Histidine Kinase Activity Introduction Membrane Receptor Kinases Type I Histidine Kinase Receptors Receptors with Several Membrane-Spanning Segments Transmembrane Signaling in Bacterial Chemotaxis Conclusions References6 Structure-Function Relationships: Chemotaxis and Ethylene Receptors Introduction Chemotaxis and Chemoreceptors The Ethylene Receptor Chemoreceptors and Membrane-Bound Histidine Proteins Kinases References7 New Insights into the Mechanism of the Kinase and Phosphatase Activities of Escherichia coli NRH (NtrB) and Their Regulation by the PII Protein Introduction Mechanism of NRII Autophosphorylation and Regulation of This Activity by PII Regulation of the Transphosphorylation Activity of NRII by PII Evidence for Conformational Alteration of NRII by PII Binding Mapping the Interaction of PII with NRII Mapping the Activities of NRII Explaining the Activities of Mutant Forms of NRII References8 Role of the Histidine-Containing Phosphotransfer Domain (HPt) in the Muhistep Phosphorelay through the Anaerobic Hybrid Sensor, ArcB Introduction HPt Domain Structure and Function of Common HPt Domains Multistep ArcB¿ArcA Phosphorelay System in Escherichia coli Anaerobiosis Advantage of Multistep Phosphorelay Multisignaling Circuitry of the ArcB¿ArcA Phosphorelay Phospho-HPt Phosphatase Is Involved in the ArcB¿ArcA Signaling Circuitry Physiological Role of SixA-Phosphatase in Response to Anaerobic Respiratory Conditions Cross-Phosphorelay Occurs on OmpR through EnvZ Osmosensor and ArcB Anaerosensor Atypical HPt Factor Is Involved in the Multistep RcsC¿YojN¿RcsB Phosphorelay HPt Domains in Higher Plants Concluding Remarks References 9 Genome-Wide Analysis of Escherichia coli Histidine Kinases Introduction Histidine Kinase Genes in the E. coli Genome Versatility of E. coli Histidine Kinases Deletion Analysis of Every Histidine Kinase Gene in the E. coli Genome DNA Microarray Analysis of Histidine Kinases for Gene Regulations References10 Signal Transmission and Specificity in the Sporulation Phosphorelay of Bacillus subtilis Introduction Structural Characterization of Phosphorelay Components Interactions of the Response Regulator with the Phosphotransferase Domain Conclusion References11 Histidine Kinases: Extended Relationship with GHL ATPases Introduction Diverse Functions Supported by a Conserved ATP-Binding Site Features of the ATP-Binding Site Mechanistic Implications Closing Remarks References12 Response Regulator Proteins and Their Interactions with Histidine Protein Kinases Introduction Regulatory Domains Effector Domains Regulation of Response Regulatory Phosphorylation Interactions of Response Regulators with Histidine Kinases and Histidine-Containing Phosphotransfer Domains Perspectives References13 Cyanophytochromes, Bacteriophytochromes, and Plant Phytochromes: Light-Regulated Kinases Related to Bacterial Two-Component Regulators Introduction to Phytochromes (Phys) Phys as Proteins Kinases? Discovery of Cyanophytochromes (CphPs) and Bacteriophytochromes (BphPs) Photochemical Properties of CphPs and BphPs Histidine Kinase Domains and Kinase Activity for CphPs and BphPs Biological Functions of Prokaryotic Phys Do Higher Plant Phys Function as Two-Component Histidine Kinases? Functions of the Kinase Activity of Phys BphP, CphP, and Phy Evolution Conclusions References14 Histidine Kinases in the Cyanobacterial Circadian System Introduction Cyanobacterial Circadian Rhythms Molecular Genetics of Cyanobacterial Circadian System: Kai Genes SasA, a KaiC-Binding Histidine Kinase as a Circadian Amplifier CikA, a Bacteriophytochrome Family Histidine Kinase as a Circadian Photic Input Factor Perspectives: Toward Further Understanding of His-to-Asp Signaling Pathways in the Circadian Network in Cyanobacteria References15 Two-Component Control of Quorum Sensing in Gram-Negative Bacteria Introduction Quorum Sensing in Vibrio harveyi Quorum Sensing in Myxococcus xanthus Conclusions References16 Intercellular Communication in Gram-Positive Bacteria Depends on Peptide Pheromones and Their Histidine Kinase Receptors Introduction Intercellular Communication by Unmodified Peptides Intercellular Communication by Modified Peptides Bacteria Speak Different Languages Peptide Pheromones Depend on Histidine Kinase Receptors The HPK10 Subfamily of Histidine Kinases References17 Initiation of Bacterial Killing by Two-Component Sensing of a "Death Peptide": Development of Antibiotic Tolerance in Streptococcus pneumoniae Introduction Cell Death and Signal Transduction Summary and Perspectives References18 Role of Multiple Sensor Kinases in Cell Cycle Progression and Differentiation in Caulobacter crescentus Introduction Temporal and Spatial Control of Cell Cycle Events Levels of Developmental Regulation Control of Differentiation by Cell Cycle Checkpoints Two-Component Signal Transduction and Cell Cycle Regulation Summary and Perspectives References19 The Slnl-Ypdl-Sskl Multistep Phosphorelay System That Regulates an Osmosensing MAP Kinase Cascade in Yeast Introduction The Common Downstream Pathway The SLN 1 Branch The SHO 1 Branch Concluding Remarks References20 Histidine Kinases of Dictyostelium Introduction Eukaryotic Histidine Kinases Dictyostelium Histidine Kinases Phenotypic Analyses Double Mutants Structure and Function of DhkA The Late Adenylyl Cyclase ACR Summary and Perspectives References21 Ethylene Perception in Arabidopsis by the ETR1 Receptor Family: Evaluating a Possible Role for Two-Component Signaling in Plant Ethylene Responses Introduction ETR1 Family Gene Structure and Biochemistry Ethylene Sensor Domain GAF-like Domain Histidine Kinase-Coupled Receptor Receiver Domain Kinase Activity in the Cytosolic Portion of ETR1 Mutational Analysis of the Ethylene Pathway TwomComponent Signaling through MAPk Kinases in Saccharomyces cerevesiae and Arabidopsis References22 Pathogenicity and Histidine Kinases: Approaches Toward the Development of a New Generation of Antibiotics Introduction Are Histidine Kinases Good Antibacterial Targets? Alternatives to High Throughput Screens: Possibilities for Structure-Based Screening for Identification Histidine of Kinase Inhibitors References23 Molecular Evolution of Histidine Kinases Introduction Domains of Histidine Kinases Evolution of Histidine Kinases Conclusion ReferencesIndex