PolyP inhibits CobB deacetylase triggering a regulatory coupling to prevent DNA replication initiation

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Polyphosphate (polyP) plays regulatory roles in cells.
• Bacteria accumulate polyP under stress, forming granules with unknown functions.
• PolyP granules are linked to cellular regulation during stress.

Purpose of the Study:

• To investigate the regulatory function of polyP in bacterial stress response.
• To elucidate the mechanism by which polyP affects DNA replication initiation in starved Escherichia coli.
• To identify the molecular targets of polyP involved in inhibiting replication.

Main Methods:

• Studying DnaA protein foci formation and oriC binding in starved E. coli.
• Investigating the interaction between polyP and CobB deacetylase.
• Measuring DnaA acetylation levels under different conditions.

Main Results:

• PolyP accumulation prevents DnaA binding to oriC in starved E. coli.
• PolyP interacts with a long CobB deacetylase variant, inhibiting its activity.
• Inhibition of CobB leads to increased DnaA acetylation, blocking replication initiation.

Conclusions:

• PolyP regulates DNA replication initiation by targeting CobB deacetylase.
• This polyP-dependent mechanism inhibits replication initiation during bacterial stress.
• Multiple regulatory pathways ensure complete inhibition of replication in stressed bacteria.