Izoleucil-tRNA-sintetaza kao meta za razvoj antibiotika

undergraduate thesis

• Title (english): Isoleucyl-tRNA synthetase as a target for antibiotic development
• Author: Goran Kokić
• Mentor: Ita Gruić-Sovulj (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2012, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Aminoacil-tRNA-sintetaze (aaRS) su enzimi koji proizvode molekule aminoacilirane tRNA potrebne za biosintezu proteina. Tijekom neovisne evolucije unutar tri glavne domene života; bakterijske, arhealne i eukariotske, neke aaRS nakupile su značajne strukturne razlike. Izoleucil-tRNA-sintetaza (IleRS), dio obitelji aaRS, dobar je primjer takve divergentne evolucije. Prokariotski i mitohondrijski oblici enzima eukariota pokazuju kraću C-terminalnu domenu s klasterom od 4 cisteina koji koordiniraju ion cinka. Eukariotski i arhealni ortolozi sadrže dulju C-terminalnu domenu bez cink-veznog motiva. Usprkos značajno većoj očuvanosti katalitičke domene, otkriveni su inhibitori koji uspješno diskriminiraju navedene tipove IleRS i ukazuju na velik potencijal za razvoj antibiotika. Mupirocin, prirodni produkt bakterije Pseudomonas fluorescens, potentni je inhibitor bakterijskog tipa IleRS i jedini je takav antibiotik koji je uveden u medicinsku praksu. Velik afinitet prema proteinima seruma i laka hidroliza u tjelesnim tekućinama, ograničile su njegovu primjenu na liječenje kožnih infekcija. Mupirocin se veže u aktivno mjesto enzima oponašajući prirodne supstrate tog enzima. Nakon vezanja, mupirocin sprječava pomicanje katalitičke petlje prema aktivnom mjestu fiksirajući otvorenu konformaciju enzima, što je dodatan mehanizam inhibicije aktivnosti IleRS. Manipulacija kemijskom strukturom tog antibiotika dovela je do otkrića još potentnijih analoga. Derivati tiomarinola, skupina antibiotika srodnih mupirocinu, pokazuju širi spektar djelovanja i poboljšanu oralnu biodostupnost. Lijekovi koji ciljaju IleRS ne koriste se samo kao baktericidni agensi. Reveromicin A specifično inducira apoptozu osteoklasta, pokazujući potencijal za liječenje osteoporoze i osteolitičkih metastaza u kostima. Ikofungipen inhibira eukariotski tip IleRS i u kliničkim ispitivanjima pokazuje dobre rezultate u liječenju diseminirajuće kandidijaze i gljivičnih infekcija središnjeg živčanog sustava.

Abstract (english)

Aminoacyl-tRNA synthetases (aaRS) are enzymes that produce aminoacylated tRNA molecules needed in protein biosynthesis. During independent evolution in three primary kingdoms; archaeal, bacterial and eukaryotic, some aaRS accumulated recognizable structural differences. Isoleucyl-tRNA synthetase (IleRS) is a good example of such divergent evolution. Shorter C-terminal domain of prokaryotic and eukaryotic mitochondrial IleRS contains cluster of four cysteine residues coordinating a zinc ion. In contrast, eukaryotic and archaeal orthologs possess longer C-terminal domain deprived of the zinc binding motif. Catalytic domain was shown to be much more conserved than the C-terminal domain. Nevertheless, selective inhibitors that discriminate between prokaryotic and eukaryotic catalytic domains have been discovered, revealing potential for drug design. Mupirocin, a natural product produced by Pseudomonas fluorescens, is a potent inhibitor of bacterial IleRS and the only antibiotic targeting this enzyme that is used in medical practice. It is restricted to topical use, given its lack of oral bioavailability. Mupirocin occupies enzyme´s active site by mimicking its natural substrates, L-isoleucine and ATP. When bound to IleRS, it prevents catalytic loop bearing conserved KMSKS signature motif to access the active site, representing additional inhibitory mechanism. Changes introduced in its chemical structure (modification of aminoacyl moiety and phosphate linker) provided much more potent analogs. Thiomarinol derivates, group of antibiotics closely related to mupirocin, exhibit even wider spectrum of activity and better oral bioavailability. Drug-targeting IleRSs are not being used only as antibacterial agents. Reveromycin A induces apoptosis specifically in osteoclasts, revealing its potential in treating bone disorders, including osteoporosis and osteolytic bone metastasis. Icofungipen inactivates eukaryotic IleRS and shows good results in treating dissseminated candidiasis and fungal CNS infection.

• Keywords: izoleucil-tRNA-sintetaza
• Keywords (english): isoleucyl-tRNA synthetase
• Language: croatian
• URN:NBN: urn:nbn:hr:217:818065
• 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: 2018-04-18 08:16:54