Biomedical subjects

Daniel J Webre

Publications and source records attributed to Daniel J Webre.

4 recordsLinked to original sources

PubMed2004

Modulated receptor interactions in bacterial transmembrane signaling.

Bacteria can detect and respond to a remarkably diverse set of environmental conditions. This ability enables motile species to integrate stimuli, to compare current surroundings with those of the recent past, and to adjust swimming behavior to move up gradients of attractants and avoid repellents. Many of the molecular details involved in the bacterial chemotaxis system have been elucidated. Several models have been proposed recently to explain how cells process external information through a patch of highly interactive transmembrane receptors and transduce this information to other components in the cytoplasm that, in turn, function to regulate motility.

Bacterial Physiological Phenomena↗

PubMed2003

Mechanism of phosphatase activity in the chemotaxis response regulator CheY.

Response regulator proteins are phosphorylated on a conserved aspartate to activate responses to environmental signals. An intrinsic autophosphatase activity limits the duration of the phosphorylated state. We have previously hypothesized that dephosphorylation might proceed through an intramolecular attack, leading to succinimide formation, and such an intramolecular dephosphorylation event is seen for CheY and OmpR during mass spectrometric analysis [Napper, S., Wolanin, P. M., Webre, D. J., Kindrachuk, J., Waygood, B., and Stock, J. B. (2003) FEBS Lett 538, 77-80]. Succinimide formation is usually associated with the spontaneous deamidation of Asn residues. We show here that an Asp57 to Asn mutant of the CheY chemotaxis response regulator undergoes an unusually rapid deamidation back to the wild-type Asp57, supporting the hypothesis that the active site of CheY is poised for succinimide formation. In contrast, we also show that the major route of phosphoaspartate hydrolysis in CheY occurs through water attack on the phosphorus both during autophosphatase activity and during CheZ-mediated dephosphorylation. Thus, CheY dephosphorylation does not usually proceed via a succinimide or any other intramolecular attack.

Amides↗

PubMed2003

Intramolecular rearrangements as a consequence of the dephosphorylation of phosphoaspartate residues in proteins.

Aspartate phosphorylation induces changes in protein conformation that are used to regulate processes ranging from gene expression and cell differentiation to cell motility and the generation of electrochemical gradients across membranes. We show here that dephosphorylation of the phosphoaspartate in the chemotaxis response regulator CheY can result in the loss of a water molecule that may be due to formation of a succinimide intermediate.

Aspartic Acid↗

PubMed2003

Bacterial chemotaxis.

Explore the source record for details and available documents.

Bacterial Physiological Phenomena↗