A role for the Gram-negative outer membrane in bacterial shape determination.
Elayne M Fivenson1, Patricia D A Rohs1, Andrea Vettiger1
1Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115.
Biorxiv : the Preprint Server for Biology
|February 13, 2023
Summary
The outer membrane strengthens Gram-negative bacteria, aiding cell shape determination and growth. This finding reveals a new role for the outer membrane in bacterial morphogenesis beyond its barrier function.
Area of Science:
- Microbiology
- Cell Biology
- Biophysics
Background:
- Gram-negative bacteria possess a complex cell envelope with cytoplasmic membrane, peptidoglycan cell wall, and outer membrane (OM).
- The peptidoglycan layer and OM contribute to structural integrity and resistance against internal turgor pressure.
- The role of the OM in bacterial morphogenesis, particularly cell shape determination, remained largely unexplored.
Approach:
- Investigated the impact of modifying lipopolysaccharide (LPS) synthesis to strengthen the OM in *Escherichia coli*.
- Assessed the effects of OM fortification on growth and shape defects in mutants lacking functional Rod system (elongasome) components.
- Examined the influence of OM strength on MreB cytoskeletal filament organization and peptidoglycan synthesis.
Key Points:
- Strengthening the OM by altering LPS composition can rescue growth and shape defects in *E. coli* mutants with impaired Rod system function.
- Enhanced OM integrity appears to restore proper MreB filament organization, crucial for directing cell wall synthesis.
- These findings suggest the OM actively participates in maintaining bacterial rod shape during elongation.
Conclusions:
- The OM plays a significant role in bacterial shape determination, complementing its established function as a diffusion barrier.
- This study highlights a previously unappreciated mechanical contribution of the OM to bacterial morphogenesis.
- Understanding the OM's role in shape determination offers new insights into bacterial cell structure and antibiotic resistance mechanisms.
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