Inorganic polyphosphate and the stringent response coordinately control cell division and cell morphology in...

Area of Science:

• Bacteriology
• Molecular Biology
• Cell Biology

Background:

• Bacteria utilize stress responses like the stringent response (mediated by (p)ppGpp) and inorganic polyphosphate (polyP) synthesis to adapt to environmental challenges.
• Both (p)ppGpp and polyP are ancient, conserved molecules involved in various cellular functions, including stress response and metabolism.
• The interplay between (p)ppGpp and polyP in regulating fundamental cellular processes remains largely unexplored.

Purpose of the Study:

• To investigate the overlapping roles of (p)ppGpp and polyP in regulating cell division, morphology, and metabolism in *Escherichia coli*.
• To elucidate the coordinated functions of these two pathways beyond their known stress-response roles.

Main Methods:

• Generation and phenotypic analysis of *E. coli* mutants lacking both (p)ppGpp and polyP synthesis.
• Microscopic examination of cell morphology, including Z-ring localization and internal structures.
• Growth assays under nutrient-limited conditions.

Main Results:

• Single disruptions in (p)ppGpp or polyP synthesis pathways led to filamentous cell formation.
• Simultaneous disruption of both pathways resulted in heterogeneous cell morphologies, including branched cells and mislocalized Z-rings.
• Mutants lacking both (p)ppGpp and polyP exhibited impaired growth under nutrient limitation, even with amino acid supplementation.

Conclusions:

• The stringent response alarmone (p)ppGpp and inorganic polyphosphate (polyP) possess previously unrecognized overlapping functions in regulating bacterial cell division and morphology.
• These pathways act in a coordinated manner to control fundamental cellular processes, extending beyond their established roles in stress response.
• The findings provide new insights into the integrated regulation of metabolism, cell division, and growth in bacteria.