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The effect of guanosine tetraphosphate (ppGpp) on HypB mediated hydrogenase maturation

De Enrique Schmidt, Teresa (2022) MOBN03 20212
Degree Projects in Molecular Biology
Popular Abstract
Potential drug to reduce bacterial survival

Recently there has been an increase in common bacterial infections being tolerant to available antibiotics, thus leading to a possible health crisis. Bacteria has developed tolerance through a small molecule called ppGpp, which is highly produced during a stress response (e.g., antibiotics). This molecule is responsible for the shutdown of a variety of molecular and cellular mechanisms to save energy for bacterial survival and regrowth once the antibiotic treatment is done. Previously, it was discovered that this molecule binds to an accessory protein (HypB protein) involved in the formation of an enzyme complex required for hydrogen gas production in bacteria. This enzyme called hydrogenase... (More)
Potential drug to reduce bacterial survival

Recently there has been an increase in common bacterial infections being tolerant to available antibiotics, thus leading to a possible health crisis. Bacteria has developed tolerance through a small molecule called ppGpp, which is highly produced during a stress response (e.g., antibiotics). This molecule is responsible for the shutdown of a variety of molecular and cellular mechanisms to save energy for bacterial survival and regrowth once the antibiotic treatment is done. Previously, it was discovered that this molecule binds to an accessory protein (HypB protein) involved in the formation of an enzyme complex required for hydrogen gas production in bacteria. This enzyme called hydrogenase is activated during anerobic and acidic conditions, to use hydrogen gas as energy for bacterial growth. Therefore, the hypothesis for this project was that ppGpp inhibits hydrogenase activity to save energy for bacterial survival under unfavorable conditions.

In this study, we tested weather the molecule influences the activity of the HypB protein, and thus the activity of hydrogenase. First, experimental work was done to obtain only our protein of interest in solution. Then, we tested the activity either with or without ppGpp and if there was a change in the protein structure. This protein is stable in solution as a dimer, meaning two compounds of the same protein are bound together. As a result, we quantified the difference of HypB protein as a dimer in solution with or without ppGpp. Secondly, we looked at the overall effect of ppGpp on the production of hydrogen gas in a living bacterium called Escherichia coli. The experiment was based on identifying if there was a general increase or decrease in hydrogenase activity under ppGpp conditions.

According to our results, ppGpp did not show a change in HypB activity, and it seemed to slightly increase stable HypB in solution. Continuously, we tested whether the binding of ppGpp to HypB affected the interaction with another accessory protein (SlyD) instead. Interaction of these two proteins is a required molecular step for a complete formation of the hydrogenase enzyme. Results showed a slight decrease between the two proteins with ppGpp. Moreover, a significant increase in hydrogenase activity and thus hydrogen gas production in the living bacterium was seen without ppGpp. The living bacterium also showed a decrease in a previous molecular step required for hydrogenase formation under ppGpp conditions. However, further experimental work is needed, with more repetition and different parameters to obtain more reliable results.

To conclude, it seems ppGpp reduces hydrogen gas production, which means hydrogenase activity decreases in the living bacterium. Data was collected under nonacidic conditions, so hydrogenase activity would be a waste of energy for the bacteria. However, when the molecule starts showing an inhibitory effect in the mechanism to form the hydrogenase enzyme is still under investigation. It would be of interest to test whether ppGpp increases hydrogen gas production in acidic environments, as this would further confirm the role of ppGpp during a stress response. Future findings could provide a breakthrough antibiotic tolerance, as hydrogenases are only found in bacteria and not in humans. It is a characteristic for a highly specific drug target for bacterial infection, which might potentially reduce the climb of antibiotic tolerance.

Master’s Degree Project in Molecular Biology, MOBN03 60 credits
Department of Biology, Lund University

Advisor: Yong Zhang
Functional Genomics, Copenhagen University (Less)
Please use this url to cite or link to this publication:
author
De Enrique Schmidt, Teresa
supervisor
organization
course
MOBN03 20212
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
9103256
date added to LUP
2022-11-16 15:02:33
date last changed
2022-11-16 15:02:33
@misc{9103256,
  author       = {{De Enrique Schmidt, Teresa}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{The effect of guanosine tetraphosphate (ppGpp) on HypB mediated hydrogenase maturation}},
  year         = {{2022}},
}