Polar Clustering of the Chemoreceptor Complex in Escherichia coli Occurs in the Absence of Complete CheA Function
| Autor: | B. P. McNamara, Janine R. Maddock, Jennifer M. Skidmore, M. M. P. Couto, D. D. Ellefson, Andalan J. Wolfe |
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| Jazyk: | angličtina |
| Rok vydání: | 2000 |
| Předmět: |
Chemoreceptor
Histidine Kinase Movement Mutant Methyl-Accepting Chemotaxis Proteins Cell Surfaces Biology medicine.disease_cause Microbiology Transduction (genetics) Bacterial Proteins medicine Escherichia coli Microscopy Immunoelectron Molecular Biology Alleles Mutation Methyl-accepting chemotaxis protein Chemotaxis Escherichia coli Proteins Histidine kinase fungi Genetic Variation Membrane Proteins Ligand (biochemistry) Cell biology Biochemistry nervous system Amino Acid Substitution bacteria biological phenomena cell phenomena and immunity Plasmids |
| Popis: | Bacterial chemotaxis requires a phosphorelay system initiated by the interaction of a ligand with its chemoreceptor and culminating in a change in the directional bias of flagellar rotation. Chemoreceptor-CheA-CheW ternary complexes mediate transduction of the chemotactic signal. In vivo, these complexes cluster predominantly in large groups at the cell poles. The function of chemoreceptor clustering is currently unknown. To gain insight into the relationship between signaling and chemoreceptor clustering, we examined these properties in several Escherichia coli mutant strains that produce CheA variants altered in their ability to mediate chemotaxis, autophosphorylate, or bind ATP. We show here that polar clustering of chemoreceptor complexes does not require functional CheA protein, although maximal clustering occurred only in chemotactically competent cells. Surprisingly, in cells containing a minimum of 13 gold particles at the cell pole, a significant level of clustering was observed in the absence of CheA, demonstrating that CheA is not absolutely essential for chemoreceptor clustering. Nonchemotactic cells expressing only CheA S , a C-terminal CheA deletion, or CheA bearing a mutation in the ATP-binding site mediated slightly less than maximal chemoreceptor clustering. Cells expressing only full-length CheA (CheA L ) from either a chromosomal or a plasmid-encoded allele displayed a methyl-accepting chemotaxis protein localization pattern indistinguishable from that of strains carrying both CheA L and CheA S , demonstrating that CheA L alone can mediate polar clustering. |
| Databáze: | OpenAIRE |
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