POSTERS - BLAST X - University of Utah

BLAST X Thurs. Morning Session
DELETION ANALYSIS OF RcsC REVEALS A NOVEL SIGNALING-PATHWAY
CONTROLLING BIOFILM FORMATION IN ESCHERICHIA COLI
Ricardo Oropeza, Rosalva Salgado, Ismael Hernandez-Lucas and Edmundo Calva
Departmento de Microbiologia Molecular, Instituto de Biotecnologia, Universidad Nacional
Autonoma de Mexico. Av. Universidad 2001. Col. Chamilpa. Cuernavaca, Morelos. Mexico, CP
62210
RcsC is a hybrid histidine kinase that forms part of a phosphorelay signal transduction
pathway with RcsD and RcsB. Besides the typical domains of a sensor kinase, i.e. the
periplasmic (P), linker (L), dimerization and H-containing (A), and ATP- binding (B), RcsC
possesses a receiver domain (D) at the carboxy-terminal domain.
In order to study the role played by each of the RcsC domains, four plasmids containing
several of these domains were constructed (i.e. PLAB, LAB, AB and ABD) and transformed in
Escherichia coli wild type. Different amounts of biofilm were produced, assessed by crystal
violet staining, depending on the RcsC domains expressed by the plasmid.
E. coli transformed with the plasmid expressing the ABD subdomains produced the
highest amount of biofilm, while the lowest amount of biofilm was produced under the control of
the PLAB expressing plasmid. This phenotype was observed in the same ratio when the
plasmids were transformed in a ΔrcsCDB strain.
Several mutants on genes involved in biofilm formation were transformed with this set of
plasmids. Biofilm formation was abolished in the pgaABCD and nhaR backgrounds but not in
the csrB and uvrY backgrounds. Our results suggest the existence of a signaling pathway
depending of RcsC but independent of RcsD and RcsB, activating biofilm formation by the
pgaABCD operon.
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