Bacterial populations, once thought to be uniform, are in fact heterogeneous mixtures of distinct cell types that become apparent when studied at the level of individual cells. Bistable (ON/OFF) gene expression epigenetically results in cell type differentiation and creates subpopulations predisposed to exploit/survive environmental change. Here we explore the unique features of the bistable expression of motility genes in Bacillus subtilis that generates mixed populations of single motile cells and non-motile chains through an epigenetic mechanism. We will measure the kinetics of switching between motility-ON and motility-OFF states and the inheritance of each state during growth. We will determine the mechanism by which the alternative sigma factor CD is controlled by both a gradual decline in transcript levels along a 27 kb operon, and regulation in response to flagellar assembly, to produce bistable gene expression. Finally, we will determine the mechanism by which a developmental regulator of unknown function, SwrA, biases the proportion of the population that is in an ON or OFF state. Motility and its control has been long-studied in Gram negative bacteria like E. coli and we intend to elevate the evolutionarily distant Gram positive B. subtilis to a premiere model system for the discovery of new paradigms of motility gene regulation. Bistability is an important new area of prokaryotic research that changes the way we think about bacterial populations. The information we gather will be directly relevant to bacterial development, antibiotic therapy, virulence gene expression, and bacterial pathogenesis.

Public Health Relevance

We will study flagellar-mediated motility in Bacillus subtilis and we will determine the kinetics, mechanism, and regulation of a bistable epigenetic switching controlling flagellin and autolysin expression.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
5R01GM093030-05
Application #
8678945
Study Section
Prokaryotic Cell and Molecular Biology Study Section (PCMB)
Program Officer
Reddy, Michael K
Project Start
Project End
Budget Start
Budget End
Support Year
5
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Indiana University Bloomington
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
City
Bloomington
State
IN
Country
United States
Zip Code
47401
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