Paradoxical enhancement of chemoreceptor detection sensitivity by a sensory adaptation enzyme.
Proc Natl Acad Sci U S A
; 114(36): E7583-E7591, 2017 09 05.
Article
em En
| MEDLINE
| ID: mdl-28827352
ABSTRACT
A sensory adaptation system that tunes chemoreceptor sensitivity enables motile Escherichia coli cells to track chemical gradients with high sensitivity over a wide dynamic range. Sensory adaptation involves feedback control of covalent receptor modifications by two enzymes CheR, a methyltransferase, and CheB, a methylesterase. This study describes a CheR function that opposes the signaling consequences of its catalytic activity. In the presence of CheR, a variety of mutant serine chemoreceptors displayed up to 40-fold enhanced detection sensitivity to chemoeffector stimuli. This response enhancement effect did not require the known catalytic activity of CheR, but did involve a binding interaction between CheR and receptor molecules. Response enhancement was maximal at low CheRreceptor stoichiometry and quantitative analyses argued against a reversible binding interaction that simply shifts the ON-OFF equilibrium of receptor signaling complexes. Rather, a short-lived CheR binding interaction appears to promote a long-lasting change in receptor molecules, either a covalent modification or conformation that enhances their response to attractant ligands.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Adaptação Biológica
/
Células Quimiorreceptoras
Tipo de estudo:
Diagnostic_studies
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article