Struktura i funkcija holoenzima na primjeru bakterijske RNA-polimeraze

undergraduate thesis

• Title (english): Structure and function of holoenzyme exemplified by bacterial RNA-polymerase
• Author: Rea Bingula
• Mentor: Ivana Weygand-Đurašević (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2013, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

RNA-polimeraza zajedno sa σ-podjedinicom čini holoenzim sposoban za specifično prepoznavanje promotorske sekvence te započinjanje važnog procesa u genskoj ekspresiji, transkripcije. Međusobno vezanje promotorskih sljedova, polimeraze i σ-podjedinice dovodi do niza alosteričkih promjena – otkrivanje veznih sljedova, stvaranje novih ionskih mostova, formiranje aktivnih mjesta, de/stabilizacija određenih struktura, itd. koje osiguravaju specifičnost holoenzima za određeni promotor. Također brojne međumolekulske interakcije s bazama promotora održavaju visoku konzerviranost određenih nukleotida (A-11, T-7) u svim domenama. Jedno od najvažnijih otkrića sigurno je bilo da se σ-podjedinica zadržava nakon same inicijacije jer je time složenost regulacije postala još veća, s obzirom da isti kompleks sada odjednom mora prelaziti između nekoliko stanja u kojima afinitet za nekoliko konstantnih sljedova u određenom trenu mora rasti ili padati, kako bi se postigao prijelaz s jednog procesa na drugi. Današnje tehnike obilježavanja fluorescentnim probama, kristalografije i masene spektrometrije otvaraju put preciznijim saznanjima o građi i interakcijama ovakvih kompleksnih struktura kao što su holoenzimi te će u budućnosti vjerojatno mnoge dosadašnje dogme također biti poljuljane.

Abstract (english)

RNA-polymerase together with the σ-subunit creates a holoenzyme capable of specific promoter sequence recognition. Thus it can commence important step of gene expression – transcription. Interwoven binding of promoter sequence, polymerase and σ-subunit leads to a number of allosteric modifications – exposure of binding sequences, salt bridge establishments, active site formation, specific structure de/stabilization , etc., all of which guarantee promoter-specificity of holoenzyme. Also, numerous intermolecular interactions with promoter bases maintain high conserved nucleotide sequence (A-11, T-7) in all living domains. One of the biggest discoveries certainly is the retaining of σ-subunit after the initiation. The complexity of regulation has increased even more since the same complex has to recognize the same sequences but with different affinity at different point in time, so the transition from one state to another can be achieved. Nowadays, techniques such as fluorescence probing, crystallography or mass spectrometry, lead to more precise organization or interaction determination inside the complex structures such as holoenzymes that will probably lead to many reconsiderations of what was thought to be dogmatic.

• Keywords: holoenzim; RNA-polimeraza
• Keywords (english): holoenzyme; RNA-polymerase
• Language: croatian
• URN:NBN: urn:nbn:hr:217:285462
• Study programme: Title: Molecular Biology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-04-23 08:43:38