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Stalkless mutants of Caulobacter crescentus
Journal of Bacteriology
|July 1, 1977
Summary
Mutations in Caulobacter crescentus can eliminate stalks, pili, and phage receptors, affecting motility. However, these stalkless mutants still exhibit normal growth and cell division, suggesting an alternative cell cycle pathway.
Area of Science:
- Microbiology
- Cell Biology
- Bacteriology
Background:
- Caulobacter crescentus exhibits polar surface structures like stalks, flagella, pili, and phage receptors during its cell cycle.
- These structures are crucial for cell cycle progression and differentiation.
Purpose of the Study:
- To investigate the function of stalks in Caulobacter crescentus.
- To identify mutations affecting polar surface structure formation and cell cycle progression.
- To understand the relationship between stalk formation, motility, and phage receptor expression.
Main Methods:
- Isolation and characterization of Caulobacter crescentus mutants resistant to DNA and RNA phages, or nonmotile.
- Phenotypic analysis of stalkless mutants, including growth rate, cell morphology, and cell division.
- Assessment of pili and phage receptor presence in stalkless mutants and their revertants.
Main Results:
- Five stalkless mutants were identified among 30 phage-resistant or nonmotile isolates.
- These mutants lacked stalks and pili, were resistant to both DNA and RNA phages, but possessed inactive flagella.
- Motile revertants regained stalk formation and phage susceptibility.
- Stalkless mutants showed normal growth and asymmetrical cell division, similar to wild-type cells.
Conclusions:
- A single mutation can pleiotropically affect stalk formation, flagellar motility, and polar morphogenesis of pili and phage receptors.
- Caulobacter crescentus can transition to a stalked-cell state without stalk formation.
- The cell cycle of stalkless mutants proceeds in an ordered sequence comparable to the wild-type.