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Characterization of an OprF-deficient mutant suggests that OprF is an essential protein for Pseudomonas fluorescens
S Chevalier1, J F Burini, M A Freulet-Marriere
1Laboratoire de microbiologie du froid, université de Rouen, IFRSI 61CNRS-Inserm, Evreux, France. sylvie.chevalier@univ-rouen.fr
Abstract:
A stable OprF-deficient mutant for Pseudomonas fluorescens strain MF0 was constructed using reverse genetics. This mutant, called MF372, showed a rounded morphology and grew more slowly in minimal medium, but not in rich medium. Contrary to other Pseudomonas strains, the loss of OprF for strain MF0 was accompanied by an altered outer membrane composition. At least three outer membrane proteins were overexpressed, apparently as a consequence of adaptive mutations. The N-terminal sequence of two of them revealed strong similarities with porins of the OprD family from P. aeruginosa. The data presented here shows that OprF may be an essential protein for this P. fluorescens strain.
Insights
Pseudomonas fluorescens OprF deficiency causes slower growth and altered outer membranes. This suggests OprF is essential for this Pseudomonas strain, impacting its cell structure and nutrient uptake.
Area of Science:
- Microbiology
- Bacterial genetics
- Protein function
Background:
- Pseudomonas fluorescens is a common bacterium with a complex outer membrane.
- Outer membrane proteins play crucial roles in bacterial structure and function.
- The OprF protein's specific role in P. fluorescens strain MF0 was not well understood.
Purpose of the Study:
- To investigate the function of the OprF protein in Pseudomonas fluorescens strain MF0.
- To characterize an OprF-deficient mutant and its phenotypic changes.
- To explore the adaptive responses of P. fluorescens to OprF loss.
Main Methods:
- Reverse genetics was used to create a stable OprF-deficient mutant (MF372).
- Phenotypic analysis of the mutant included morphology and growth rate assessments in different media.
- Outer membrane composition was analyzed, and protein sequences were compared.
Main Results:
- The OprF-deficient mutant (MF372) exhibited a rounded morphology and reduced growth in minimal medium.
- Outer membrane composition was altered in the mutant, with overexpression of at least three proteins.
- Two overexpressed proteins showed sequence similarity to OprD family porins from P. aeruginosa.
Conclusions:
- OprF appears to be an essential protein for Pseudomonas fluorescens strain MF0.
- Loss of OprF triggers adaptive mutations affecting outer membrane protein composition.
- The findings suggest a significant role for OprF in maintaining cell shape and potentially nutrient transport in this strain.