Regulation of cell signaling by the cytoplasmic domains of the heat-stable enterotoxin receptor: identification of autoinhibitory and activating motifs
| Autor: | J. S. Almenoff, L. A. Kindman, F. de Sauvage, K K Mandal, X. L. Rudner |
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| Rok vydání: | 1995 |
| Předmět: |
Cell signaling
DNA Complementary Receptors Peptide Mutant Bacterial Toxins Molecular Sequence Data Receptors Enterotoxin Biology medicine.disease_cause Transfection Cyclase Cell Line Enterotoxins Epitopes Chlorides Enterotoxigenic Escherichia coli Chlorocebus aethiops medicine Cyclic AMP Animals Point Mutation Amino Acid Sequence Receptor Conserved Sequence Sequence Tagged Sites Multidisciplinary Escherichia coli Proteins Guanylate cyclase 2C Haplorhini Recombinant Proteins Cell biology Biochemistry Receptors Guanylate Cyclase-Coupled Guanylate Cyclase Mutagenesis Site-Directed Signal transduction Peptides Oligopeptides Intracellular Signal Transduction Research Article |
| Zdroj: | Proceedings of the National Academy of Sciences of the United States of America. 92(11) |
| ISSN: | 0027-8424 |
| Popis: | Infection with enterotoxigenic Escherichia coli is a leading cause of traveler's diarrhea. Many enterotoxigenic E. coli strains produce heat-stable enterotoxin (ST), a peptide that binds to the intestinal receptor guanylyl cyclase C known as STaR. The toxin-receptor interaction elevates intracellular cGMP, which then activates apical chloride secretion, resulting in secretory diarrhea. In this report, we examine how the intracellular domains of STaR participate in the propagation and regulation of signaling. We show that STaR exists as an oligomer in both the presence and the absence of toxin. We also demonstrate that deletion of the intracellular kinase-homology domain produces a constitutively active mutant, suggesting that this domain subserves an autoinhibitory function. Finally, we constructed a point mutant within a highly conserved region of the cyclase domain that completely inactivates the catalytic activity of guanylyl cyclase. Cotransfection of this point mutant with wild-type receptor causes a dominant-negative effect on receptor activation. This suggests that interaction of receptor subunits is required for toxin-induced activation and that the cyclase domain is involved in this essential interaction. We propose that the binding of ST to STaR promotes a conformational change across the cell membrane. This removes the inhibitory effects of the kinase-homology domain and promotes an interaction between cyclase domains that leads to receptor activation. The data suggest a paradigm of signal transduction that may also be relevant to other members of the guanylyl cyclase receptor family. |
| Databáze: | OpenAIRE |
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