Conformational suppression of inter-receptor signaling defects
1Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
Summary
Bacterial chemoreceptors form trimers of dimers, enabling sensitive chemical detection. Mutations in one receptor can be suppressed by mutations in another, revealing cooperative signaling mechanisms essential for bacterial motility.
Area of Science:
- Microbiology
- Biochemistry
- Molecular Biology
Background:
- Motile bacteria exhibit high sensitivity to chemical gradients.
- Chemoreceptors are physically clustered, potentially forming cooperative arrays.
- Receptors form trimers of dimers at their cytoplasmic tips, crucial for cluster assembly and function.
Purpose of the Study:
- Investigate the role of receptor interactions in bacterial chemotaxis.
- Characterize mutations affecting chemoreceptor function and assembly.
- Elucidate the mechanism of cooperative signaling in bacterial chemoreceptors.
Main Methods:
- In vivo crosslinking to study receptor complex formation.
- Isolation and characterization of specific mutations in chemoreceptors (Tsr and Tar).
- Epistasis analysis to determine functional relationships between mutated receptors.
Main Results:
- Mutations at trimer contact sites of Tsr abrogate function, with some blocking heterologous receptors (Tsr*).
- Mutations in Tar (Tar()) restored function to Tsr* receptors, acting allele-specifically.
- Tar() receptors showed varied clustering efficiencies and some regained function with suppressible Tsr* partners.
Conclusions:
- Suppression of Tsr* by Tar() mutations suggests compensatory changes in mixed receptor complexes.
- Trimer-of-dimer interactions are vital for cooperative signaling and high-gain responses in bacterial chemotaxis.
- These findings highlight the importance of receptor organization for sensitive environmental sensing.
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