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