Karatan Lab
Lindsay Porter
Ece Karatan
karatane@appstate.edu
Appalachian State University
Department of Biology
Rankin Science North
319 (Office), 303 (Lab)
828-262-6742
Characterization of MbaA and its role
in V. cholerae biofilm formation
Elucidation of the role of MbaA on Vibrio cholerae biofilm formation
The V. cholerae protein MbaA is an integral membrane protein with both periplasmic and cytoplasmic domains. When MbaA is deleted experimentally, there is a marked increase in biofilm formation. The cytoplasmic portion of MbaA contains two important enzymatic domains, the GGDEF and EAL domains, involved in the synthesis and degradation of the secondary messenger cyclic-di-GMP (c-di-GMP), respectively. GGDEF domains are diguanylate cyclases which catalyze the formation of c-di-GMP, while conversely the EAL domains are phosphodiesterases that degrade c-di-GMP. These domains are thus named for the single letter amino acid sequences found in the active sites. Both of these domains are highly conserved in bacteria. The fusion of both of these domains in MbaA may suggest both positive and negative control of c-di-GMP by this protein, although the enzymatic activity of either of these domains has yet to be studied. In general, an increase in the cellular levels of c-di-GMP yields activation of biofilm formation. Because MbaA is a repressor of biofilm formation and is thought to be a phosphodiesterase, it is reasonable to believe that it is breaking down c-di-GMP and that the EAL domain is active. I am interested in elucidation of the function of the various domains of MbaA and their involvement in biofilm formation