POSTERS - BLAST X - University of Utah

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