Structural and functional analysis of hybrid proteasome Strukturna i funkcionalna analiza hibridnog proteasoma

master's thesis

• Title (croatian): Strukturna i funkcionalna analiza hibridnog proteasoma
• Author: Katarina Belačić
• Mentor: David Haselbach (mentor)
• Mentor: Nenad Malenica (mentor)
• Committee member: Nenad Malenica (predsjednik povjerenstva)
• Committee member: Antun Alegro (član povjerenstva)
• Committee member: Marin Ježić (član povjerenstva)
• Committee member: Inga Marijanović (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2018-11-23, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Proteasomes perform the majority of proteolysis that occurs in cells, and thereby, perform
crucial roles in regulation of cellular processes such as cell division and death, signal
transduction, immune response, metabolism and protein quality control. The catalytic heart of
proteasome complexes is the 20S core particle (20S CP) which activity is regulated through
association with different activators – 19S regulatory particle (19SRP), PA28ab, PA28g and
PA200. The hybrid proteasome complex contains the 19S RP on the one side and PA28 or
PA200 on the opposite side of the same 20S CP. The hybrid proteasome complexes can be
found under native conditions, or their formation can be induced (e.g., by interferon-γ
treatment). The exact function of hybrid proteasomes is still unknown and their structures have
never been thoroughly investigated. The structural analysis of hybrid proteasome complexes
from bovine testes and interferon-g treated human rectal carcinoma cells by single particle
cryo-electron microscopy has resulted only in the structures of the PA200 hybrid proteasome
complex, however at a too low resolution for reliable structural insights. Meanwhile, the
peptide pattern in the presence of 19S-20S-PA28ab or 19S-20S-PA28g complexes was found
to be changed in comparison with the one obtained without PA28 complexes, indicating that
PA28 allosterically regulates the cleavage specificities of 19S-20S proteasome complex.

Abstract (croatian)

Proteasom je proteinski kompleks zadužen za razgradnju proteina unutar stanice te je stoga
važan za regulaciju staničnih procesa – diobu i smrt stanice, prijenos signala, imunološki
odgovor, metabolizam, provjeru kvalitete proteina i razvoj. Katalitički aktivan dio čini 20S
kompleks čija je aktivnost regulirana vezanjem različitih aktivatora poput 19S regulatornog
kompleksa (19S RP), PA28ab, PA28g te PA200. Hibridni proteasom sadrži 19S RP na jednoj
i PA28 ili PA200 na drugoj strani istog 20S kompleksa. Hibridni proteasomi mogu biti prisutni
u normalnim uvjetima ili njihov nastanak može biti potaknut (npr. stimulacijom interferonom-
γ). Međutim, točna funkcija hibridnih proteasoma je još uvijek nepoznata, a struktura nikada
nije detaljno istraživana. Strukturna analiza krio-elektronskom mikroskopijom pojedinačnih
čestica hibridnih proteasoma izoliranih iz tkiva goveđih testisa i stanica ljudskog rektalnog
karcionoma tretiranih interferonom- γ pokazala je prisutnost samo hibridnih proteasoma koji
sadrže PA200 aktivator. Međutim, zbog preniske rezolucije nisu dobivene pouzdane strukturne
informacije. Također, pronađeno je da se u prisutnosti kompleksa 19S-20S-PA28ab ili 19S-
20S-PA28g, uzorak peptidnih fragmenata odabranog proteinskog supstrata razlikuje od uzorka
dobivenog u odustnosti PA28 aktivatora. Takav rezultat ukazuje na to da PA28 aktivator
alosterički regulira specifičnosti proteolitičkog cijepanja 20S-19S kompleksa.

• Keywords: 20S core particle; 19S regulatory particle; hybrid proteasome; cleavage specificities; cryo-electron microscop
• Keywords (croatian): 20S kompleks; 19S regulatorni kompleks; hibridni proteasom; specifičnosti proteolitičkog cijepanja; krio-elektronska mikroskopija
• Language: english
• URN:NBN: urn:nbn:hr:217:182054
• Study programme: Title: Molecular Biology; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra molekularne biologije (magistar/magistra molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2019-11-23
• Created on: 2018-12-04 11:48:12