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Published on: August 13, 2017
Negative control in two-component signal transduction by transmitter phosphatase activity
TuAnh Ngoc Huynh1, Valley Stewart
1Food Science Graduate Group Department of Microbiology, University of California, Davis, California, USA.
Molecular Microbiology
|September 8, 2011
Summary
Two-component systems use bifunctional sensor transmitters for signaling control. A new hypothesis proposes conserved residues catalyze phosphatase activity, resetting signaling and preventing cross-talk.
Area of Science:
- Molecular Biology
- Biochemistry
- Cell Signaling
Background:
- Bifunctional sensor transmitters in two-component systems regulate signaling pathways.
- These transmitters exhibit both positive (autokinase) and negative (phosphatase) control over response regulators.
- The mechanism of transmitter phosphatase activity, crucial for signal termination and cross-talk suppression, remained largely unknown.
Purpose of the Study:
- To elucidate the molecular mechanism underlying the phosphatase activity of bifunctional sensor transmitters.
- To investigate the catalytic residues and conformational requirements for transmitter phosphatase function.
- To understand how phosphatase activity is regulated in relation to autokinase activity.
Main Methods:
- Hypothetical mechanism proposed based on conserved residue analysis.
- Comparison with known auxiliary phosphatase mechanisms (e.g., CheZ, CheX).
- Analysis of transmitter conformation and interactions with the receiver domain.
Main Results:
- A hypothesis suggests conserved Gln, Asn, or Thr residues catalyze dephosphorylation via hydrogen bonding with water.
- This mechanism resembles that of auxiliary phosphatases and may be conserved in two-component signal transduction.
- Transmitter phosphatase activity requires specific conformations and receiver interactions, distinct from autokinase-competent states.
Conclusions:
- The study proposes a novel, conserved catalytic mechanism for transmitter phosphatase activity in two-component systems.
- This mechanism explains how signaling is reset and cross-talk is suppressed.
- Reciprocal regulation of positive and negative activities is achieved through dynamic control of transmitter conformations.
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