POSTERS - BLAST X - University of Utah

BLAST X Mon. Evening Session
A "FOUR COMPONENT" SIGNAL TRANSDUCTION SYSTEM REGULATES
DEVELOPMENTAL PROGRESSION IN MYXOCOCCUS XANTHUS
Sakthimala Jagadeesan, Bongsoo Lee, and Penelope I. Higgs
Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, D35043
Marburg, Germany
Myxococcus xanthus responds to starvation by entering a multicellular developmental
program in which 10 5 cells first aggregate into mounds and then within these mounds,
differentiate into environmentally resistant spores. Under standard laboratory conditions,
formation of spores within the mounds (fruiting bodies) takes approximately 72 hours. We have
previously demonstrated that progression through the developmental program appears to be
regulated by an atypical two component signal (TCS) transduction system consisting of four
TCS homologs (RedC, RedD, RedE, and RedF). While RedC appears to be a typical
membrane bound histidine kinase, RedD consists solely of two receiver domains. RedE is a
soluble histidine kinase-like protein, and RedF is a single receiver domain response regulator.
Based on a combination of genetic and biochemical analyses, we propose a model for how
these four Red proteins function together to regulate progression through the developmental
program. Our data suggests that development is repressed when the RedC histidine kinase
phosphorylates RedF, a single domain response regulator. Developmental repression is
relieved when, in response to an unknown signal(s), RedC is instead induced to phosphorylate
the response regulator RedD. Surprisingly, the phosphoryl group is then transferred from RedD
to the histidine kinase-like protein, RedE. RedE is then likely made accessible to RedF-P,
whereupon it removes RedF’s phosphoryl group. We present the data that supports this model.
Furthermore, we will address how progression through the developmental program is modulated
by the Red system.
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