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.
Summary
The outer membrane of Gram-negative bacteria helps maintain cell shape by supporting the peptidoglycan layer. Strengthening the outer membrane can correct shape defects in bacteria with faulty cell wall synthesis machinery.
Area of Science:
- Microbiology
- Cell Biology
- Bacterial Pathogenesis
Background:
- Gram-negative bacteria possess a complex cell envelope with cytoplasmic membrane, peptidoglycan (PG), and outer membrane (OM).
- The PG layer is crucial for bacterial shape and osmotic stability, while the OM acts as a barrier and load-bearing layer.
- The OM's role in bacterial morphogenesis, particularly cell shape determination, remains incompletely understood.
Purpose of the Study:
- To investigate the role of the outer membrane (OM) in bacterial morphogenesis.
- To determine if the OM contributes to cell shape maintenance in Gram-negative bacteria.
- To explore the interplay between OM structure and peptidoglycan synthesis in cell shape determination.
Main Methods:
- Utilized *Escherichia coli* mutants with defects in the Rod complex (elongasome) responsible for cell elongation.
- Manipulated lipopolysaccharide (LPS) synthesis and modification to alter OM properties.
- Observed the effects of OM changes on bacterial growth, cell shape, and MreB cytoskeletal filament organization.
Main Results:
- Strengthening the OM by altering LPS synthesis or modification suppressed growth and shape defects in Rod complex mutants.
- Outer membrane fortification restored the proper orientation of MreB cytoskeletal filaments.
- This indicates that the OM influences the spatial regulation of cell wall synthesis by the Rod complex.
Conclusions:
- The outer membrane plays a significant role in bacterial morphogenesis, contributing to rod shape propagation during cell growth.
- OM fortification can compensate for defects in the cell wall synthesis machinery, highlighting its structural importance.
- These findings expand our understanding of the OM's functions beyond its role as a diffusion barrier and in antibiotic resistance.
More Related Videos
Related Concept Videos
01:22Bacterial Cell Wall
58
The bacterial cell wall is an essential structural component that encases the plasma membrane, preserving cellular integrity, determining shape, and protecting against osmotic stress. This rigid yet flexible structure primarily comprises peptidoglycan, a polymer that forms a mesh-like matrix conferring mechanical strength and flexibility.Peptidoglycan Composition and StructurePeptidoglycan, the core of the bacterial cell wall, comprises alternating units of N-acetylglucosamine (NAG) and...
58
01:29Microbial Morphologies
47
Bacterial and archaeal cells exhibit remarkable diversity in shape and structure, critical in their adaptability and functionality. Among bacteria, the most commonly observed shapes include cocci and bacilli. Cocci are spherical and may exist singly or in groupings such as pairs (diplococci), chains (streptococci), clusters (staphylococci), or tetrads. Bacilli, in contrast, are rod-shaped and can also occur as single cells, in pairs, or chains, depending on their environmental and genetic...
47
01:18Flagella and Motility in Bacteria
56
Flagella are specialized, thread-like structures that extend from a bacteria's cell envelope. They play a crucial role in motility and chemotaxis. Their structural organization and functioning exemplify sophisticated biological engineering, enabling bacterial survival and adaptability in diverse environments.Structure of the FlagellumA bacterial flagellum consists of three key components: the filament, the hook, and basal body. The filament, a long, helical structure composed of repeating...
56
01:19Formation of Lipopolysaccharides
41
Lipopolysaccharides (LPS) are crucial components of the outer membrane of Gram-negative bacteria, serving both structural and functional roles. It contributes to membrane stability and protects bacteria from host immune responses. LPS is composed of three major regions—lipid A, a core oligosaccharide, and an O antigen. The biosynthesis and assembly of LPS involve a highly coordinated set of enzymatic reactions and transport mechanisms. Additionally, LPS is recognized as an endotoxin,...
41
01:29Cytoskeletal Proteins in Bacteria
3.5K
Bacterial cells were initially considered simple, randomly organized structures lacking a cytoskeleton. However, the discovery of cytoskeleton homologs in bacteria led to the change of this opinion. Bacterial cytoskeletal filaments regulate the cell shape, cell polarity, cell division, and partitioning of plasmids during cell division. It was later discovered that bacterial cytoskeletal proteins, mainly actin and tubulin homologs, are diverse compared to their eukaryotic counterparts. On the...
3.5K
01:30Bacterial Phylum Actinobacteria
36
Coryneform bacteria are gram-positive, aerobic, nonmotile rods that exhibit irregular, club-shaped, or V-shaped arrangements. Their V-shape results from snapping division, where the inner cell wall layer forms the cross-wall, while the outer layer remains intact until it ruptures on one side, causing the daughter cells to bend away.The primary genera are Corynebacterium and Arthrobacter. Corynebacterium includes diverse species, ranging from saprophytes to pathogens like Corynebacterium...
36