Microbiology Editor's Choice: a vital protein in Vibrio cholerae biofilm formation

Posted on April 9, 2021   by Microbiology Society

Each month, a manuscript published in our flagship journal Microbiology is chosen by a member of the Editorial Board. This month, the paper is titled ‘A mutagenic screen reveals NspS residues important for regulation of Vibrio cholerae  biofilm formation’ and was chosen by Dr Isabelle Martin-Verstraete. 

Vibrio cholerae is thought to exist primarily as a biofilm in aquatic environments and uses the NspS/MbaA signalling system to detect polyamines and differentiate between the natural aquatic environment and the human intestine based on the presence of specific polyamines. Using a screening strategy to isolate mutants of NspS showing a reduced ability to form biofilm, this paper brings new insights on the structure-function analysis of the NspS protein, identifying residues potentially important for norspermidine binding and interactions with MbaA.  

A mutagenic screen reveals NspS residues important for regulation of Vibrio cholerae  biofilm formation  

The NspS/MbaA signalling system is used by Vibrio cholerae to sense and respond to molecules called polyamines that regulate biofilms. The NspS residues that are responsible for binding polyamines and interacting with MbaA are not known. We designed a random mutagenesis experiment to identify NspS residues important for biofilm formation. We also generated a model of the NspS protein as a tool to predict where these amino acids resided. Ultimately, we showed most residues that affected biofilm formation were located on two distinct regions of the NspS protein that may be important for NspS/MbaA interactions. 

We spoke with authors Ece Karatan and Misty L. Kuhn to find out more: 

What is your institution and how long have you been there?  

Ece Karatan Appalachian State University. I’ve been here since 2005. 

Misty L. Kuhn San Francisco State University. I have been here since 2014.  

What is your research area?   

Ece Karatan Regulation of biofilm formation in V. cholerae by polyamines and identification and characterization of polyamine synthesis, transport and signalling pathways in V. cholerae.  

Misty L. Kuhn My laboratory studies protein structure/function relationships using protein biochemistry, enzymology and structural biology. Our focus is mainly on bacterial proteins called acetyltransferases, but we have studied other types of proteins too. In recent years we have become interested in how polyamine acetyltransferases catalyse their reactions, how they are regulated, and how they may contribute to bacterial biofilms, especially in Vibrio cholerae.  

What inspired you to research this topic?   

Ece Karatan I’ve always been fascinated by signal transduction mechanisms cells use to sense and respond to their environments.  I studied signal transduction in the context of chemotaxis in Bacillus subtilis in graduate school.  When I started my postdoc, one of the available projects were was to study signalling pathways that regulated biofilm formation in V. cholerae. We discovered the pathway described in this article and showed that it responded to a polyamine called norspermidine. I continued to study this pathway when I started my own lab and also expanded into identifying and characterizing the pathways for synthesis and transport of polyamines in V. cholerae. 

Misty L. Kuhn It was mostly by chance. My post-doctoral research advisor asked me to develop an enzyme assay to study acetyltransferase activity for some projects we were working on with collaborators. This became the basis for new projects in my own laboratory at SFSU.  

What is the most rewarding part of your research?  

Ece Karatan The joy of discovery. Being the first to figure out the answer to a particular biological question.  Training the next generation of scientists. 

Misty L. Kuhn Collaborating with others to learn new things. It is so much more motivating and exciting to work as a team to discover new insight, whether it be with my students or collaborators at other institutions. 

What would you be doing if you weren't a scientist?  

Ece Karatan Probably a physician.  

Misty L. Kuhn I am not really sure because I didn’t know I would become a scientist. Maybe I would be a pastry chef or teach young adults how to cook.