Biokemijska karakterizacija hidrolaze s dvojnom enzimskom aktivnošću iz mahovine Physcomitrella patens

doctoral thesis

• Title (english): Biochemical characterization of a dual enzymatic activity hydrolase from moss Physcomitrella patens
• Author: Zrinka Karačić
• Mentor: Branka Salopek-Sondi (mentor)
• Committee member: Jasmina Rokov Plavec (predsjednik povjerenstva)
• Committee member: Ivana Leščić Ašler (član povjerenstva)
• Committee member: Željka Vidaković Cifrek (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2018-06-18, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry
• Universal decimal classification (UDC): 54 - Chemistry. Crystallography. Mineralogy

Abstract

Nudix-dipeptidil-peptidaza III je biljni enzim s dvojnom hidrolaznom aktivnošću: dipeptidilpeptidaznom
(DPP III) i fosfataznom (Nudix). Biokemijski su okarakterizirani homolozi iz
mahovine (Physcomitrella patens) i uročnjaka (Arabidopsis thaliana). C-terminalna domena
oba homologa predstavlja atipičnu DPP III s obzirom na aktivno mjesto (pentapeptid HEXXH
umjesto heksapeptida HEXXGH u tipičnim DPP III), te je slabije aktivna prema sintetskim
supstratima u usporedbi s tipičnim, do sada istraženim DPP III. N-terminalna domena je član
nadporodice Nudix proteina. Utvrđeno je da Nudix domena ima fosfataznu aktivnost prema
supstratima izopentenil-difosfatu i dimetilalil-difosfatu, prekursorima u sintezi izoprenoida.
Funkcionalnim istraživanjima na mutantama mahovine P. patens koje ne eksprimiraju ovaj
enzim pokazano je da on sudjeluje u metabolizmu biljnih hormona citokinina. Preliminarni
rezultati analize ekspresije gena u mahovini u prisutnosti stresora sugeriraju da enzim Nudix-
DPP III sudjeluje u odgovoru biljaka na stres (sušu, solni i oksidacijski stres). Zaključno,
predložen je naziv izopentenil-difosfat-fosfohidrolaza za novopronađenu enzimsku aktivnost.

Abstract (english)

Nudix-dipeptidyl peptidase III is a plant enzyme with dual hydrolase activity: dipeptidylpeptidase
III (DPP III) and phosphatase (Nudix). Homologues from moss (Physcomitrella
patens) and angiosperm (Arabidopsis thaliana) were biochemically characterized. C-terminal
domain of both homologues represents an atypical DPP III considering the active site
(pentapeptide HEXXH instead of hexapeptide HEXXGH in typical DPPs III), and it is less
active towards synthetic supstrates than typical, formerly characterized DPPs III. N-terminal
domain is a member of Nudix superfamily. It was established that it has phosphatase activity
towards isopentenyl-diphosphate and dimethylallyl-diphosphate, precursors in isoprenoid
sythesis. Functional research on moss P. patens knock-out mutants showed that this enzyme
is involved in cytokinin metabolism. Preliminary analysis of gene expression in the presence
of stressors suggests that Nudix-DPP III enzyme is involved in plant response to stress
(drought, salt and oxidative stress). Finally, the name isopentenyl diphosphate
phosphohydrolase is suggested for the newly identified enzyme activity.

• Keywords: Nudix-hidrolaza; dipeptidil-peptidaza III; Physcomitrella patens; izopentenil-difosfat
• Keywords (english): Nudix hydrolase; dipeptidyl-peptidase III; Physcomitrella patens; isopentenyl-diphosphate
• Language: croatian
• URN:NBN: urn:nbn:hr:217:805640
• Study programme: Title: Doctoral study in chemistry; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija (doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija)
• Type of resource: Text
• Extent: 130 str. ; 30 cm
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2020-06-18
• Created on: 2018-07-11 09:38:51