POSTERS - BLAST X - University of Utah

BLAST X Poster #39
UNDERSTANDING THE FUNDAMENTAL ELEMENTS OF SIGNALING IN THE Tar
CHEMORECEPTOR
Christopher Adase, Michael Manson
Texas A&M University, 3258 TAMU, BSBE Room 303
The Tar chemoreceptor of Escherichia coli has two different attractants: L-aspartate,
which binds directly to the receptor; and maltose, which interacts with the receptor indirectly
though maltose-binding protein (MBP). Tar also senses Ni 2+ and Co 2+ as repellents. The Tsr
chemoreceptor interacts directly with L-serine as an attractant and also senses repellents such
as indole, acetate, and benzoate in an unknown manner. Tar-Tsr and Tsr-Tar chimeras have
been created using the endogenous Nde1 site found at the end of the region encoding their
respective HAMP domains. The Tar-Tsr hybrid could sense Ni 2+ as a repellent, whereas the Tsr-
Tar hybrid could not. Thus, Ni 2+ probably interacts, directly or indirectly, with an area within the
first 256 amino acids of Tar. Using knockouts of nikA, nikB, and nikC, we tested whether
periplasmic NikA is necessary and sufficient for Ni 2+ taxis, as has been reported, and whether
Ni 2+ must be taken up into the cytoplasm. I have also created additional Tar-Tsr chimeras to
determine exactly what portion of Tar is involved in Ni 2+ sensing. Repellent taxis was assayed
using novel microfluidic techniques developed by the Jayaraman lab in the Department of
Chemical Engineering at Texas A&M.
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