Supervisors info:
Κωνσταντίνος Βοργιάς, Καθηγητής, Τμήμα Βιολογίας, Εθνικό & Καποδιστριακό Πανεπιστήμιο Αθηνών (Επιβλέπων)
Αλέξανδρος Γεωργακίλας, Αναπληρωτής Καθηγητής, Τμήμα Σ.Ε.Μ.Φ.Ε., Εθνικό Μετσόβιο Πολυτεχνείο
Βασιλική Οικονομίδου, Επίκουρη Καθηγήτρια, Τμήμα Βιολογίας, Εθνικό & Καποδιστριακό Πανεπιστήμιο Αθηνών
Summary:
Over the last 20 years, a great number of scientific articles have appeared in the bibliography, which have been published in well-validated scientific journals and aimed at elucidating the mechanism of protein stability. In these articles, the researchers compared the open reading frames from various microorganism genomes, which organisms have an optimal growth temperature, ranging from the freezing temperature of water to above the boiling temperature of the water. In the whole study, they made a general assumption. This assumption was that the optimum growth temperature of a microorganism and the thermal stability of the proteins are in absolute correlation. From a biological point of view, we would accept that, of course, a protein from a hyperthermophilic organism can not be unstable. But, is it correct to assume that a protein produced from a mesophilic organism is less stable and that the protein from a psychophile is not stable at all?
These assumptions have not been demonstrated experimentally, and we can’t compare genomics at protein level and produce statistical correlations. The research, so far, has been based on these data, and the results produced may have provided significant data for each protein through point mutations in relation to their thermostability, but failed to give a holistic or systemic view of the phenomenon.
These assumptions are also impossible, because our experience so far has shown that a very small number of amino acids (<5%) is related to the structural stability of proteins, and this percentage is too small to withstand assumptions involving at least > 5% error.
Based on the above data, we tried to find out if there is a correlation between optimal growth temperature and thermal stability, based on experimental results obtained from the literature, combined with experimental experience of our laboratory.
The aim of this diploma thesis is to investigate whether the temperature of growth (GOT) is related to the melting temperature (Tm) of the proteins an organism produces for its survival. In particular, we want to investigate if the growth temperature of an organism provides some information about Tm. Therefore, we try to investigate whether two random variables (GOT and Tm) are statistically dependent on each other and whether they are correlated. If there is such a relationship between the two variables, we could say that the temperature at which the organisms grow is a major factor in the stability of a protein. Otherwise, we could say that the non-dependence of one variable on the other amplifies the prevailing idea, that the stability of a protein against the extreme growth temperature arises only from the intrinsic stability of the protein, which is imprinted on its primary structure and the quality of its amino acid residues. The systematic study of this target phenomenon is to provide us with sufficient data,so as to be able to predict with great confidence possible ways of protein stabilization, which is a nodal point of synthetic biology.
Keywords:
Protein Thermostability, Optimal Growth Temperature, Melting Temperature of protein, Correlation, Dependence
