Dissertation defence (Chemistry): MSc Randa Mahran

MSc Randa Mahran defends the dissertation in Chemistry titled “MONITORING CELLULAR GUANOSINE TRIPHOSPHATE (GTP) AND GTP ASSOCIATED PROTEINS” at the University of Turku on 01 March 2024 at 12.00 (University of Turku, Main building, Tauno Nurmela lecture hall, Turku).

Opponent: Professor Paul Brennan (University of Oxford, UK)
Custos: Docent Harri Härmä (University of Turku)

Doctoral Dissertation at UTUPub: https://urn.fi/URN:ISBN:978-951-29-9615-5


Summary of the Doctoral Dissertation:

Nucleotides are important molecules that are present in all human cells. They are the building blocks of our genetic material. The most important nucleotides are ATP and GTP, they give energy to our cells and control other cell activities. The levels of these nucleotides need to be precise in our cells, or it can lead to diseases.

GTP has a special function related to small proteins called GTPases that are responsible for regulating cell growth and survival. Understanding the functions of GTP is crucial, especially its link to various diseases, as it will help researchers advance their knowledge and potentially finding new ways to treat diseases. However, theres a challenge. While there are plenty of techniques available for measuring ATP, its not the same for GTP.
There are two main types of methods used to study nucleotides: luminescence-based and separation-based methods. While separation methods have benefits, they need trained experts and specific equipment, and their ability to process a large number of samples is limited. On the other hand, luminescence-based methods are faster but are mostly designed for detecting ATP.

In this PhD project, methods to measure GTP concentration in the cell and to study small GTPases and their interaction with GTP, were developed. To measure the level of GTP in cells, a high-throughput assay was developed. This assay uses a special antibody that can detect cellular GTP with high accuracy. The results from this new assay were similar to those obtained with the gold standard method, showing that its just as accurate but much faster.

A new method called the Protein-Probe was also created. This method was used to study the heat stability of small GTPases. The research also looked at how the recent FDA approved KRAS/G12C covalent inhibitors bind to RAS GTPases. The Protein-Probe method has a sensitivity level much higher than existing methods, therefore requires smaller amounts of sample materials and reduces the cost.

Another technique introduced in the project is the FRET-Probe. It was compared to the Protein-Probe method in a thermal stability test and was used to check the chemical stability of proteins when exposed to different denaturing chemicals. The FRET-Probe offers additional advantages over the Protein-Probe, as it works at a neutral pH and has a more straightforward assay protocol.
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