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Repurposing a chemosensory macromolecular machine
Davi R Ortega1, Wen Yang2, Poorna Subramanian1
1Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd, Pasadena, CA, C1125, USA.
Nature Communications
|April 29, 2020
Summary
The evolution of complex molecular machines, like the chemosensory system controlling bacterial flagellar motility in Escherichia coli, is revealed. Ancestral forms suggest a stress response pathway where one system was lost after another took over its functions.
Area of Science:
- Microbiology
- Evolutionary Biology
- Biochemistry
Background:
- The evolution of complex macromolecular machines is not well understood.
- Chemosensory systems control essential cellular functions, including bacterial motility.
Purpose of the Study:
- To investigate the evolutionary origins of the chemosensory machinery controlling flagellar motility in Escherichia coli.
- To identify ancestral forms and trace the evolutionary trajectory of this system.
Main Methods:
- Electron cryotomography to characterize ancestral structures.
- Bioinformatic analysis to trace evolutionary events through γ-Proteobacteria.
Main Results:
- Identified ancestral chemosensory machinery in Vibrio cholerae, Pseudomonas aeruginosa, Shewanella oneidensis, and Methylomicrobium alcaliphilum.
- Evidence suggests these ancestral systems function in a stress response pathway.
- Traced key evolutionary events in γ-Proteobacteria, revealing the takeover of one system (F7) by another (F6), leading to the loss of F6.
Conclusions:
- The chemosensory system in E. coli evolved from at least two ancient systems.
- One ancient system (F7) assumed the inputs and outputs of another (F6), which was subsequently lost.
- This evolutionary process sheds light on the development of complex molecular machinery.
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