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 #19<br />
SEARCHING THE PHYSIOLOGICAL SIGNAL(S) THAT REGULATE THE ACTIVITY OF THE<br />
SENSOR KINASE BarA<br />
González-Chávez, R., Rodríguez-Rangel, C., Georgellis, D.<br />
Departamento de Genética Molecular, Instituto de Fisiología Celular, UNAM, México, D.F.<br />
04510.Tel. 56-22-57-38. dimitris@ifc.unam.mx<br />
The BarA/UvrY two-component system <strong>of</strong> Escherichia coli comprises the BarA protein<br />
as the histidine sensor kinase, and UvrY as the cognate response regulator. The E. coli<br />
BarA/UvrY two-component system (TCS) and its homologues in other gram-negative bacteria,<br />
such as BarA/SirA <strong>of</strong> Salmonella, ExpS/ExpA <strong>of</strong> Erwinia, VarS/VarA <strong>of</strong> Vibrio, and GacS/GacA<br />
<strong>of</strong> Pseudomonas species, have been shown to positively control expression <strong>of</strong> the noncoding<br />
CsrB and CsrC RNAs in E. coli. These small regulatory RNAs together with the 6.8 kD CsrA<br />
protein constitute the Csr (carbon storage regulation) system, a post-transcriptional regulatory<br />
system that has pr<strong>of</strong>ound effects on central carbon metabolism, motility and multicellular<br />
behavior <strong>of</strong> E. coli.<br />
No physiological signals able to regulate the BarA sensor kinase and thereby control the<br />
UvrY response regulator have so far been identified for any <strong>of</strong> the orthologous TCSs. However,<br />
in a recent study it was demonstrated that pH lower than 5.5 provides an environment that does<br />
not allow activation <strong>of</strong> the BarA/UvrY signaling pathway, providing an important physiological<br />
tool for further experimentation in this direction.<br />
Here, we present experiments aiming at identifying the environmental signal(s) to which<br />
BarA respond. Our results indicate that short fatty acids, such as formate and acetate, act as<br />
direct signals for BarA. The implications <strong>of</strong> our findings on the overall physiology <strong>of</strong> the cell are<br />
be discussed.<br />
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