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Analysis of molecular diffusion in ftsK cell-division mutants using laser surgery
Mattias Goksör1, Alfredo Diez, Johan Enger
1Department of Physics, Chalmers University of Technology and Göteborg University, Fysikgränd 3, SE-41296 Göteborg, Sweden.
EMBO Reports
|August 30, 2003
Summary
Escherichia coli cells with faulty FtsK proteins form chains instead of dividing properly. Our study shows these compartments are sealed, preventing molecule diffusion between cells.
Area of Science:
- Cellular biology
- Microbiology
- Genetics
Background:
- The FtsK protein is crucial for proper chromosome segregation during bacterial cell division.
- Mutations in FtsK can lead to aberrant cell division, resulting in chain formation in Escherichia coli.
- It was hypothesized that cell compartments in these chains might remain interconnected, allowing molecule diffusion.
Purpose of the Study:
- To investigate the cytoplasmic connectivity between cell compartments in chain-forming Escherichia coli ftsK mutants.
- To determine if small molecules can diffuse between cells in these chains.
Main Methods:
- Development of a specialized optical workstation for real-time imaging and microsurgery on sub-micrometer cellular objects.
- Surgical incision of cell poles in Escherichia coli.
- Tracking the diffusion of propidium iodide (PI), a fluorescent molecule, in real-time following incisions.
Main Results:
- Propidium iodide (PI) was unable to diffuse between individual cell compartments in chain-forming ftsK mutants.
- This indicates a lack of cytoplasmic continuity between the cells in the chains.
- The cytoplasm of the cell compartments in the chains appears to be fully separated.
Conclusions:
- The cytoplasmic compartments of chain-forming ftsK mutant Escherichia coli cells are fully separated.
- The observed chain formation is not due to incomplete membrane fusion allowing molecule exchange.
- This finding clarifies the nature of cell separation defects in ftsK mutants.