Gunther Lukat

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Bacterial motility and gene expression are controlled by a family of phosphorylated response regulators whose activities are modulated by an associated family of protein-histidine kinases. In chemotaxis there are two response regulators, CheY and CheB, that receive phosphoryl groups from the histidine kinase, CheA. Here we show that the response regulators(More)
The chemotactic responses of bacteria such as Escherichia coli and Salmonella typhimurium are mediated by phosphorylation of the CheY protein. Phospho-CheY interacts with the flagellar motor switch to cause tumbly behavior. CheY belongs to a large family of phosphorylated response regulators that function in bacteria to control motility and regulate gene(More)
The histidine protein kinase CheA plays an essential role in stimulus-response coupling during bacterial chemotaxis. The kinase is a homodimer that catalyzes the reversible transfer of a gamma-phosphoryl group from ATP to the N-3 position of one of its own histidine residues. Kinetic studies of rates of autophosphorylation show a second order dependence on(More)
Signal transduction in bacterial chemotaxis involves transfer of a phosphoryl group between the cytoplasmic proteins CheA and CheY. In addition to the established metal ion requirement for autophosphorylation of CheA, divalent magnesium ions are necessary for the transfer of phosphate from CheA to CheY. The work described here demonstrates via fluorescence(More)
The signal transduction system that mediates bacterial chemotaxis allows cells to modulate their swimming behavior in response to fluctuations in chemical stimuli. Receptors at the cell surface receive information from the surroundings. Signals are then passed from the receptors to cytoplasmic chemotaxis components: CheA, CheW, CheZ, CheR, and CheB. These(More)
The reduced forms of cytochrome P-450cam and chloroperoxidase were examined by proton NMR spectroscopy. The pH and temperature dependences of the proton NMR spectra of both ferrous enzymes are reported. A series of alkyl mercaptide complexes of both synthetic and natural-derivative iron(II) porphyrins was also examined. The proton NMR spectra of these(More)
The proton nuclear magnetic resonance spectra of several chloroperoxidase-inhibitor complexes have been investigated. Titrations of chloroperoxidase with azide, thiocyanate, cyanate, or nitrite ions indicate that only the chloroperoxidase-thiocyanate complex exhibits slow ligand exchange on the 360-MHz NMR time scale. The temperature dependence of the(More)
APL@Voro is a new program developed to aid in the analysis of GROMACS trajectories of lipid bilayer simulations. It can read a GROMACS trajectory file, a PDB coordinate file, and a GROMACS index file to create a two-dimensional geometric representation of a bilayer. Voronoi diagrams and Delaunay triangulations--generated for different selection models of(More)
Thyroid peroxidase was isolated from porcine thyroids by two methods. Limited trypsin proteolysis was employed to obtain a cleaved enzyme, and affinity chromatography was used to isolate intact thyroid peroxidase. Enzyme isolated by both methods was used in the examination of the heme site of native thyroid peroxidase and its complexes by EPR spectroscopy.(More)