▪ Abstract Most prokaryotic signal-transduction systems and a few eukaryotic pathways use phosphotransfer schemes involving two conserved components, a histidine protein kinase and a response regul...

Two-component signal transduction

Fast time scale dynamics of protein backbones: NMR relaxation methods, applications, and functional consequences.

Unicellular microorganisms experience “life on the edge,” as they have little ability to change their environment and face fierce competition for limited resources. They must therefore respond to a barrage of environmental cues in a rapid and accurate manner. Among multicellular organisms,

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The Two-Component System: Regulation of Diverse Signaling Pathways in Prokaryotes and Eukaryotes

A temperature-sensitive lethal mutant of Staphylococcus aureus was found to harbor a mutation in the uncharacterized two-component histidine kinase (HK)-response regulator (RR) pair encoded by yycFG; orthologues of yycFG could be identified in the genomes of Bacillus subtilis and other gram-positive bacteria. Sequence analysis of the mutant revealed a point mutation resulting in a nonconservative change (Glu to Lys) in the regulator domain of the RR at position 63. To confirm that this signal transduction system was essential, a disrupted copy of either the RR (yycF) or the HK (yycG) was constructed with a set of suicide vectors and used to generate tandem duplications in the chromosome. Resolution of the duplications, leaving an insertion in either the yycF or the yycG coding region, was achieved only in the presence of an additional wild-type copy of the two open reading frames. Phenotypic characterization of the conditional lethal mutant showed that at permissive growth conditions, the mutant was hypersusceptible to macrolide and lincosamide antibiotics, even in the presence of the ermB resistance determinant. Other mutant phenotypes, including hypersensitivity to unsaturated long-chain fatty acids and suppression of the conditional lethal phenotype by high sucrose and NaCl concentrations, suggest that the role of the two-component system includes the proper regulation of bacterial cell wall or membrane composition. The effects of this point mutation are strongly bactericidal at the nonpermissive temperature, indicating that this pathway provides an excellent target for the identification of novel antibiotics.

Role in Cell Permeability of an Essential Two-Component System in Staphylococcus aureus

Bacteria are continually bombarded by a multitude of chemicals from their environment, some of which may serve as potential sources of carbon, nitrogen, and energy, while others may act as poisons of their metabolic and regulatory processes. This mix of environmental signals and insults is highly variable and most certainly locale dependent. The potential for an organism to grow and divide within any locale or ecological niche is determined genetically by its repertoire of genes and by its capacity to induce new gene expression to cope with new environments. Often a bacterial infection results from an organism moving from an environment where its presence is benign (e.g., the gastrointestinal system) to another environment where it poses a serious problem (e.g., the urinary tract). This movement between ecological niches requires that the organism “sense” its presence in the new environment and “respond” by expressing new genetic information to permit it to occupy and grow within it. Success in this endeavor is the result of the sum of incremental genetic responses to the new environment of the host.

Two-Component Signal Transduction as a Target for Microbial Anti-Infective Therapy

NMR has been employed for structural and dynamic studies of the bacterial response regulator, Spo0F This 124-residue protein is an essential component of the sporulation phosphorelay signal transduction pathway in Bacillus subtilis Three-dimensional 1H, 15N, and 13C experiments have been used to obtain full side chain assignments and the 1511 distance, 121 dihedral angle, and 80 hydrogen bonding restraints required for generating a family of structures (14 restraints per residue) The structures give a well-defined (α/β)5 fold for residues 4−120 with average rms deviations of 059 A for backbone heavy atoms and 102 A for all heavy atoms Analyses of backbone 15N relaxation measurements demonstrate relative rigidity in most regions of regular secondary structure with a generalized order parameter (S2) of 09 ± 005 and a rotational correlation time (τm) of 70 ± 05 ns Loop regions near the site of phosphorylation have higher than average rms deviation values and T1/T2 ratios suggesting significant int

High-resolution NMR structure and backbone dynamics of the Bacillus subtilis response regulator, Spo0F: implications for phosphorylation and molecular recognition.

Lawrence P. Mcintosh

Papers

High-resolution NMR structure and backbone dynamics of the Bacillus subtilis response regulator, Spo0F: implications for phosphorylation and molecular recognition.