Principal Investigator Alan Grossman
Gene expression and development are often affected by multiple physiological processes and signals. The mechanisms of signal integration have been active areas of research in many fields. The initiation of sporulation in B. subtilis is activated by nutrient depletion and high population density, inhibited by DNA damage, and requires DNA replication and a functional TCA cycle. Our work demonstrated that all of these conditions and the cognate signals function to regulate the activation (phosphorylation) of Spo0A, the key transcription factor required for the initiation of sporulation. Sporulation starts only when all signals are appropriate for development.
We analyzed gene expression in single cells and showed that activation of the transcription factor is a stochastic process and cells must achieve a threshold level to fully initiate developmental gene expression. If an individual cell falls short of that threshold, then developmental gene expression is essentially off.