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PAS domain containing chemoreceptor couples dynamic changes in metabolism with chemotaxis
Zhihong Xie1, Luke E Ulrich, Igor B Zhulin
1Department of Biochemistry, University of Tennessee, Knoxville, TN 37996, USA.
Summary
Bacteria use chemoreceptors to find ideal environments. This study identifies AerC, a redox sensor in Azospirillum brasilense, guiding bacteria to optimal microaerophilic conditions for nitrogen fixation.
Area of Science:
- Microbiology
- Bacterial Physiology
- Chemosensing
Background:
- Motile bacteria utilize chemoreceptors to sense environmental cues for growth.
- The specific roles of individual chemoreceptors in bacterial lifestyles remain largely unexplored.
- Azospirillum brasilense fixes nitrogen under microaerobic conditions.
Purpose of the Study:
- To characterize the AerC chemoreceptor in Azospirillum brasilense.
- To elucidate the function of AerC as a redox sensor.
- To understand how AerC contributes to bacterial navigation towards optimal growth conditions.
Main Methods:
- Characterization of the AerC chemoreceptor.
- Analysis of AerC's redox sensing mechanism involving FAD cofactors.
- Investigating AerC's cellular localization and correlation with gene expression.
- Studying the behavioral response of Azospirillum brasilense mediated by AerC.
Main Results:
- AerC functions as a redox sensor, directing Azospirillum brasilense to microaerophilic environments.
- AerC utilizes FAD cofactors within its PAS domains to monitor the redox state of the electron transport system.
- AerC localizes to cell poles, and its activity is linked to cellular FAD levels during nitrogen fixation.
- AerC-mediated chemotaxis is prominent during nitrogen fixation, optimizing sensing for current metabolic needs.
Conclusions:
- AerC is a key redox sensor enabling Azospirillum brasilense to optimize nitrogen fixation.
- Chemotaxis is dynamically coordinated with cellular physiology, particularly during active metabolic processes like nitrogen fixation.
- This study reveals a mechanism linking chemosensing to metabolic status in bacteria.
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