An atypical Phr peptide regulates the developmental switch protein RapH

Area of Science:

• Microbiology
• Bacterial Development
• Signal Transduction

Background:

• Bacillus subtilis differentiates under nutrient limitation and high density.
• Rap proteins (response regulator aspartate phosphatases) control B. subtilis differentiation.
• Phr peptides regulate Rap protein activity, with previously identified pentapeptides.

Purpose of the Study:

• Identify and validate the sequence of an atypical Phr peptide, PhrH.
• Characterize the expression and function of PhrH.
• Propose a new class of Phr signaling molecules.

Main Methods:

• In vivo and in vitro analyses.
• Luciferase reporter bioassay.
• In vitro biochemical experiments.

Main Results:

• PhrH is a hexapeptide (TDRNTT), distinct from known pentapeptides.
• PhrH expression is driven by a promoter within rapH and requires sigma(A).
• PhrH antagonizes RapH's dephosphorylation of Spo0F and sequestration of ComA, promoting sporulation and competence.

Conclusions:

• PhrH is the prototype of a new class of six-amino-acid Phr signaling molecules.
• This new class likely includes PhrI, involved in regulating RapI and ICEBs1.
• PhrH plays a crucial role in B. subtilis developmental pathways.