POSTERS - BLAST X - University of Utah

BLAST X Mon. Morning Session
INTEGRATED CONTROL OF CAULOBACTER CELL ENVELOPE PHYSIOLOGY BY A
HYBRID TWO-COMPONENT/ECF SIGMA FACTOR SIGNALING NETWORK
Robert Foreman, Erin Purcell, Aretha Fiebig, Dan Siegal-Gaskins & Sean Crosson
Department of Biochemistry and Molecular Biology, University of Chicago, 929 E. 57th St.,
Chicago, IL 60637
We present evidence that Caulobacter crescentus encodes a regulatory network that
integrates information about two different signals, visible light and oxidative/osmotic stress, to
regulate the cell envelope and cell adhesion. In this hybrid signaling system, light signals via
the LovK histidine kinase and oxidative/osmotic stress signals via the ECF sigma factor σ T are
integrated to regulate cell envelope physiology. Caulobacter LovK, exhibits light-controlled
autokinase activity and forms a two-component signaling system with the single-domain
receiver protein, LovR. We have shown that the LovK/LovR system can function to modulate
cell adhesion in response to blue light. LovK/LovR is a negative regulator of σ T , an envelope
stress sigma factor that is critical for cell survival under osmotic and oxidative stress. σ T , in turn,
is a positive transcriptional regulator of the lovK/lovR two-component system. This feedbackregulated
signaling network can serve as a model to probe how bacterial cells integrate and
coordinate their responses to multiple environmental queues.
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