POSTERS - BLAST X - University of Utah

BLAST X Thurs. Evening Session
FUNCTION OF MULTIPLE CHEMOTAXIS-LIKE PATHWAYS IN MEDIATING CHANGES IN
MOTILITY PATTERNS AND CELLULAR MORPHOLOGY IN AZOSPIRILLUM BRASILENSE
Amber N. Bible 1 , Zhihong Xie 1 , Matthew Russell 1 and Gladys Alexandre 1,2
1 Department of Biochemistry, Cellular and Molecular Biology and 2 Department of Microbiology,
The University of Tennessee, Knoxville, TN 37996
Molecular details on bacterial chemotaxis have been derived from studies of model
organisms such as Escherichia coli and Bacillus subtilis which genome encode for a single
chemotaxis pathway that functions to modulate changes in motility patterns. Comparative
genomics analysis indicates that the genome of many bacteria possess multiple chemotaxis-like
(Che) pathways. A. brasilense is a plant-associated bacterium that can differentiate in at least
four different cell types (swimmer, swarmer, aggregated and cyst cells). Transition from one cell
type to the other depends on the environmental (especially nutritional) conditions. One of the 4
Che-like pathways (Che1) encoded within the genome of the alphaproteobacterium A.
brasilense was recently shown to regulate changes in motility patterns, cell-to-cell aggregation
concomitant with changes in cell length (Bible et al., 2008). We will present evidence for the role
of two Che pathways and several chemoreceptors in controlling the ability of cells to modulate
multiple cellular responses, including cell length, that suggest that cross-regulation between
parallel chemotaxis pathways may function to coordinate and integrate a set of cellular
functions. Experimental evidence suggests that proteins that function in the
methylation/demethylation of chemoreceptors may have a critical role in this cross-regulation.
The implications in the lifestyle of this bacterium will also be discussed in lights of recent
experimental evidence obtained.
Bible, A. N., Stephens, B. B., Ortega, D. R., Xie, Z. and G. Alexandre (2008) Function of a
chemotaxis-like signal transduction pathway in modulating motility, cell clumping, and cell length
in the alphaproteobacterium Azospirillum brasilense. J Bacteriol 190: 6365-6375.
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