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The G-protein FlhF has a role in polar flagellar placement and general stress response induction in Pseudomonas
S Pandza1, M Baetens, C H Park
1Department of Microbiology and Immunology, Sherman Fairchild Science Building, 299 Campus Drive, Stanford University, Stanford, CA 94305, USA.
Abstract:
The flhF gene of Pseudomonas putida, which encodes a GTP-binding protein, is part of the flagellar-motility-chemotaxis operon. Its disruption leads to a random flagellar arrangement in the mutant (MK107) and loss of directional motility in contrast to the wild type, which has polar flagella. The return of a normal flhF allele restores polar flagella and normal motility to MK107; its overexpression triples the flagellar number but does not restore directional motility. As FlhF is homologous to the receptor protein of the signal recognition particle (SRP) pathway of membrane protein translocation, this pathway may have a role in polar flagellar placement in P. putida. MK107 is also compromised in the development of the starvation-induced general stress resistance (SGSR) and effective synthesis of several starvation and exponential phase proteins. While somewhat increased protein secretion in MK107 may contribute to its SGSR impairment, the altered protein synthesis pattern also appears to have a role.
Insights
Disrupting the flhF gene in Pseudomonas putida causes random flagellar arrangement and loss of directional motility. This gene is crucial for polar flagella formation and impacts stress resistance and protein synthesis.
Area of Science:
- Microbiology
- Molecular Biology
- Bacterial Motility
Background:
- The flhF gene in Pseudomonas putida encodes a GTP-binding protein essential for flagellar motility.
- Wild-type P. putida exhibits polar flagella and directional motility, regulated by the flagellar-motility-chemotaxis operon.
- The flhF gene product shows homology to the signal recognition particle (SRP) pathway receptor, suggesting a role in protein translocation.
Purpose of the Study:
- To investigate the role of the flhF gene in flagellar arrangement, motility, and protein synthesis in Pseudomonas putida.
- To explore the potential involvement of the SRP pathway in polar flagellar placement.
Main Methods:
- Gene disruption and allelic replacement of the flhF gene in P. putida.
- Analysis of flagellar arrangement and motility using microscopy and motility assays.
- Assessment of protein synthesis patterns and starvation-induced general stress resistance (SGSR) in wild-type and mutant strains.
Main Results:
- flhF disruption resulted in random flagellar arrangement and loss of directional motility.
- Restoration of a functional flhF allele rescued polar flagella and motility.
- Overexpression of flhF increased flagellar number but did not restore directional motility.
- The flhF mutant (MK107) showed impaired starvation-induced general stress resistance (SGSR) and altered protein synthesis.
Conclusions:
- The flhF gene is critical for establishing polar flagellar arrangement and directional motility in P. putida.
- The SRP pathway may play a role in the polar localization of flagella.
- flhF also influences bacterial stress resistance and protein homeostasis, indicating a broader cellular function beyond motility.