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Title:Molekularna dinamika kvadrupleksa DNK 1KF1
Authors:ID Kos, Saša (Author)
ID Brumen, Milan (Mentor) More about this mentor... New window
Files:.pdf MAG_Kos_Sasa_2014.pdf (1,89 MB)
MD5: A93329D7672A40C76AE3FBF64F879AF8
 
Language:Slovenian
Work type:Master's thesis/paper
Typology:2.09 - Master's Thesis
Organization:FZV - Faculty of Health Sciences
Abstract:Telomerni del DNK se nahaja na koncu kromosomov in je bistvenega pomena za normalno delovanje celice. Kromosome varuje pred degradacijo in nezaželeno rekombinacijo ter deluje kot neke vrste števec celične delitve. Pri vsaki delitvi celice se telomerni del nekoliko skrajša, kar posledično vodi v celično smrt. Takšen mehanizem preprečuje neomejeno delitev oz. nesmrtnost celic. Normalne celice se delijo med štirideset- in šestdesetkrat (t. i. Hayflickova meja). Rakaste celice so nesmrtne, se delijo neskončno krat, zato potrebujejo mehanizem za podaljševanje telomerjev, kar pogosto dosežejo s pomočjo encima telomeraze. Kvadrupleksi so terciarne strukture DNK in nastajajo v telomernem delu, ki je bogat z gvanini. Zavirajo delovanje telomeraze in otežujejo proces podaljševanja telomerov, ki je lahko impliciran pri rakastih obolenjih. Stabilizacija kvadrupleksov, npr. s pomočjo ligandov predstavlja eno izmed možnih tarč pri onkološkem zdravljenju. Namen tega magistrskega dela je preučitev vpliva prisotnosti ali odsotnosti kalijevih kationov v centralnem kanalu kvadrupleksa z oznako 1KF1 na stabilnost celotne strukture ter na stabilnost posameznih komponent kvadrupleksa. Stabilnost smo kvantificirali s pomočjo vrednosti srednjega odklona od kristalne strukture. Za pristop smo izbrali metodo simulacije molekularne dinamike s pomočjo programa GROMACS, torej eksperimente in silico. S simulacijo molekularne dinamike v dolžini 10 ns smo pokazali, da je struktura 1KF1 presenetljivo stabilna tudi brez kalijevih kationov. Podrobnejša analiza je pokazala, da ima kalij najbolj izrazit stabilizacijski efekt na povezovalne zanke kvadrupleksa, v manjši meri tudi na gvaninske tetrade, medtem ko brez kalijevih kationov struktura bolj niha (izmerjeno kot RMSD), vendar je še vedno relativno stabilna. Rezultati magistrskega dela so primerna osnova za nadaljnje preučevanje stabilnosti kvadrupleksov z molekularno dinamiko ter za iskanje drugih ligandov, ki stabilizirajo strukturo.
Keywords:kvadrupleks, molekularna dinamika, 1KF1, GROMACS, rak, telomer, DNK, tetrada, G-tetrade, genetika raka, nestabilnost telomerov
Place of publishing:Maribor
Publisher:[S. Kos]
Year of publishing:2014
PID:20.500.12556/DKUM-46835 New window
UDC:575.112(043.2)
COBISS.SI-ID:2065828 New window
NUK URN:URN:SI:UM:DK:QVFIGVJD
Publication date in DKUM:02.02.2015
Views:2332
Downloads:269
Metadata:XML DC-XML DC-RDF
Categories:FZV
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Secondary language

Language:English
Title:Molecular Dynamics of DNA Quadruplex 1KF1
Abstract:Telomeric DNA can be found at the ends of chromosomes and are essential for normal functioning of the cell. It protects chromosomes from degradation, unwanted recombination and it serves as a kind of counter of cell division. At every cell division, telomeres are slightly shortened, which finally leads to cell death. Such a mechanism prevents unlimited cell division and immortality. Normal cells divide between forty and sixty times (also known as the Hayflick limit). Cancerous cells are immortal, divide infinitely, so they need mechanism for telomere elongation. This is usually achieved by telomerase enzyme activity. Quadruplexes are tertiary structures of DNA, that are formed at the telomere region, rich in guanines. They inhibit telomerase activity and telomere elongation, that might be implicated in cancer. Stabilization of quadruplexes by ligands might be one of the targets for oncological treatments. The purpose of this master’s dissertation is to describe effect of presence/non-presence of potassium ions in the central channel of quadruplex 1KF1 on stability of structure as a whole and its various subunits. Stability was quantified by measuring root mean square deviation from reference crystal structure - RMSD. Experiments were performed in silico by means of molecular dynamics, using application GROMACS. By simulating molecular dynamics in length of 10 ns, we have shown that structure of 1KF1 is remarkably stable, even in absence of potassium ions. Further analysis revealed, that potassium has most pronounced stabilization effect on the connecting loops of quadruplex and to a lesser degree on guanine tetrads. Without potassium ions, structure is still quite stable, but oscillates more (measured in terms of RMSD). Results of this master’s thesis can be used as a basis for further research on quadruplex stability using molecular dynamics. It could also be used to search for other ligands, that could stabilize structures.
Keywords:quadruplex, molecular dynamics, 1KF1, GROMACS, cancer, telomer, DNA, RNA, tetrade, G-tetrade, cancer genetics, telomere instability


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