Identifying an NO Detoxification Regulator Using S-Nitrosylation in Vibrio Cholera




Associate Professor of Microbiology

Project Summary

Thanks to the Ruth Marcus Kanter College Alumni Society Undergraduate Research Grant, I was able to continue research with Dr. Jun (Jay) Zhu during the summer of 2017 in the Perelman School of Medicine’s Department of Microbiology. With the mentorship of Jessie Larios Valencia, I researched to find the conditions in which aphB would repress the transcription of hmpA, genes found in Vibrio cholera, the causative agent of cholera. hmpA is the only gene in V. cholera known to detoxify the nitric oxide produced by our immune system to kill this bacterium. In addition, aphB was recently found by our lab to act as a transcriptional regulator of hmpA in V. cholera. However, although this was discovered through molecular biology techniques such as qPCR, we had yet to get results that proved this in vitro. Finding experimental conditions for this in vitro could help advance our knowledge so that we could prevent V. cholera colonization and resistance to our immune system in vivo.

Through this experience, I further advanced my knowledge of the research process and gained experience in designing protocols and planning ahead for the next day’s experiment. Once again, I was reminded that research is a very long, repetitive, and complicated process, as I could not get the results I was looking for 99% of the time. I also learned how rewarding it could be, as on the very last day, I finally found a condition in vitro where the DaphB mutant V. cholera strain had a significantly different survivability than the wild type strain. In AT glucose, the DaphB mutant had about a 4x lower survivability in a pH around 6.7 and in a nitrate concentration between 0.3 and 3mM than in other pHs. The next step would be to understand how the acidified conditions as well as the specific nitrate concentration affect hmpA transcription and how it could be applied in vivo to prevent V. cholera from colonizing inside the human gut.

This research contributed to my educational experience, as I had just taken a molecular biology course at Penn. All the material I learned about regarding genes, transcription, and translation was relevant to my research, and I would not have been able to understand the background information and data from previous research leading up to this if I had not taken this course.

Finally, I would like to thank Jay, Jessie, and the rest of the Zhu lab for the support and an overall great summer research experience. I look forward to continuing research with everyone in the lab in the future!