Abstract
The metabolism of pathogenic microorganisms has to be flexible and the efficient replication of
pathogenic bacteria in the host depends on an active adaptation process. Vibrio cholerae is exposed to a
variety of environments within the human host and eventually has to adapt to the nutrients available at its
preferred infection site, the small intestine. The small intestine is the part of the gastrointestinal tract where the
majority of digestion and absorption of food takes place, thus providing a variety of nutrients for the bacteria.
As V. cholerae start to cause the profuse diarrhea that is the hallmark of the disease, the bacteria have to once
again adapt to the resulting changes in nutrient availability to continue the infection process. It can therefore be
expected that the metabolic status in V. cholerae changes substantially during the course of infection and that
changes in metabolism are coordinated with virulence gene expression. Although a link between the metabolic
status and virulence factor expression has been well described in several pathogens, it has not been
investigated in detail in V. cholerae. Our preliminary results suggest that different availability of certain carbon
sources that have relevance to in vivo conditions affect virulence gene expression in V. cholerae. Moreover,
we found that mutations in membrane respiration as well as central metabolism genes, such as enzymes
involved in the TCA cycle, affect virulence factor expression in V. cholerae. Based on our observations with
defined mutants in the PTA-ACK pathway we concluded that acetyl-CoA (acCoA), but not acetyl-phosphate,
plays a role in this signal transduction. We hypothesize that this link between metabolism and virulence gene
regulation in V. cholerae occurs via post-translational protein modification, specifically by lysine acetylation of
key virulence regulatory proteins. Importantly, a recent study of the global acetylome of V. cholerae revealed
lysine acetylation of several important virulence regulatory proteins, including TcpP, AphB, and PhoB. By
combining modern mass spectrometry analyses with genetic and biochemical analyses we expect to better
understand the mechanism by which acCoA affects virulence factor transcription. We will also examine the
roles of putative V. cholerae acetyltransferase genes in virulence factor modification as well as determine
additional overall protein acetylation patters (acetylomes). Thus, our study has the potential to, for the first
time, demonstrate a role of lysine acetylation in V. cholerae virulence factor regulation and will further establish
the importance of central metabolism in the pathogenesis of this organism. Overall, we expect to gain insights
into the metabolic pathways of this organism per se and its relation to virulence as an important aspect of host-
pathogen interaction. Ultimately, this information could lead to novel intervention strategies aimed at
modulating the interplay of central metabolites and virulence factor expression, not only for V. cholerae but
potentially other pathogens.