COUPLING THE PHOSPHOTRANSFERASE SYSTEM AND THE METHYL-ACCEPTING CHEMOTAXIS PROTEIN-DEPENDENT CHEMOTAXIS SIGNALING PATHWAYS OF ESCHERICHIA-COLI

Autor(en): LUX, R
JAHREIS, K
BETTENBROCK, K
PARKINSON, JS
LENGELER, JW
Stichwörter: AUTOPHOSPHORYLATION; BACTERIAL CHEMOTAXIS; BACTERIOPHAGE-T7 RNA-POLYMERASE; ENZYME I; ENZYME-I; HISTIDINE KINASE; HPR; KINASE CHEA; MANNITOL PERMEASE; Multidisciplinary Sciences; PHOSPHOENOLPYRUVATE; SALMONELLA-TYPHIMURIUM; Science & Technology - Other Topics; SUGAR-TRANSPORT; TRANSDUCTION
Erscheinungsdatum: 1995
Herausgeber: NATL ACAD SCIENCES
Journal: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volumen: 92
Ausgabe: 25
Startseite: 11583
Seitenende: 11587
Zusammenfassung: 
Chemotactic responses in Escherichia coli are typically mediated by transmembrane receptors that monitor chemoeffector levels with periplasmic binding domains and communicate with the flagellar motors through two cytoplasmic proteins, CheA and CheY. CheA autophosphorylates and then donates its phosphate to CheY, which in turn controls flagellar rotation. E. coli also exhibits chemotactic responses to substrates that are transported by the phosphoenolpyruvate (PEP)-dependent carbohydrate phosphotransferase system (PTS). Unlike conventional chemoreception, PTS substrates are sensed during their uptake and concomitant phosphorylation by the cell. The phosphoryl groups are transferred from PEP to the carbohydrates through two common intermediates, enzyme I (EI) and phosphohistidine carrier protein (HPr), and then to sugar-specific enzymes II. We found that in mutant strains HPr-like proteins could substitute for HPr in transport but did not mediate chemotactic signaling. In in vitro assays, these proteins exhibited reduced phosphotransfer rates from EI, indicating that the phosphorylation state of EI might link the PTS phospho-relay to the flagellar signaling pathway. Tests with purified proteins revealed that unphosphorylated EI inhibited CheA autophosphorylation, whereas phosphorylated EI did not. These findings suggest the following model for signal transduction in PTS-dependent chemotaxis. During uptake of a PTS carbohydrate, EI is dephosphorylated more rapidly by HPr than it is phosphorylated at the expense of PEP. Consequently, unphosphorylated EI builds up and inhibits CheA autophosphorylation. This slows the flow of phosphates to CheY, eliciting an up-gradient swimming response by the cell.
ISSN: 00278424
DOI: 10.1073/pnas.92.25.11583

Show full item record

Page view(s)

2
Last Week
0
Last month
0
checked on Mar 3, 2024

Google ScholarTM

Check

Altmetric