Leucin kao signalna molekula

undergraduate thesis

• Title (english): Leucine as a signal molecule
• Author: Anja Kostelac
• Mentor: Ita Gruić-Sovulj (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2016, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Biosignalizacijom se stanice (tkiva kod višestaničnih organizama) prilagođavaju izvanstaničnim uvjetima (staničnom okruženju) i na posredan način komuniciraju s okolinom tako da aktiviraju ili utišaju ekspresiju ciljanih gena, a time i metaboličke puteve. Signalizacija se temelji na pretvorbi primljenog izvanstaničnog signala u unutarstanični signal koji potiče ili utišava ciljane stanične procese. Prijenos signala uključuje proces umnažanja signala i prevođenja jedne vrste signala u drugi signal koja stanici predstavlja određenu informaciju. Jedna od signalnih molekula je i aminokiselina L-leucin. Molekula L-leucina je signal koji označava uvjete energetskog obilja okoline,a prenosi se u stanicu transporterom LAT1. Cilj ovog rada bio je opisati L-leucin kao signalnu molekulu koja djeluje na transkripciju gena te metabolizam. Regulatorni protein ovisan o leucinu, Lrp, i protein Sestrin2 su unutarstanični senzori leucina, a vezanjem leucina su potaknuti na konformacijsku promjenu. Lrp, protein iz bakterije Escherichia coli, je transkripcijski regulator koji prenosi informaciju leucina na molekulu DNA čime se aktivira/utiša transkripcija gena. Na ovaj način L-leucin djeluje na transkripciju gena tRNA, rRNA, katabolizma aminokiselina, fimbrija i transkripcijskih faktora. Sestrin2 je citosolni protein sisavaca koji prenosi singal L-leucina preko posredničkih proteina do krajnjeg akceptora signala - proteinskog kompleksa mTORC1. mTORC1 je arhitektura koji sadrži protein-kinazu mTOR koja fosforilacijom ciljanih proteina potiče ili inhibira njihovu aktivnost. Fosforilirani proteini sudjeluju u sintetskim reakcijama proteina i lipida, metabolizmu koji sudjeluje u pretvorbi energije i autofagiji. Na taj način L-leucin djeluje na metaboličke puteve stanice.

Abstract (english)

Biosignalization helps cells to adapt to the extracellular conditions (environment) and indirectly communicate with environment by activating/silencing expression of target genes and metabolism, respectively. Signalization is based on conversion of extracellular signal to the intracellular signal which activates or inhibits many cellular processes. Transduction of the signal includes the process of signal amplification and signal translation from one type to another. After the signal has been interpreted, it provides a cell a specific information. One of the signal molecules is an amino acid L-leucine. The aim od this report was to present L-leucine as a signal molecule for gene transcription and metabolism. L-leucine is an signal that indicates nutrient-rich conditions and is transported into the cell by LAT1 transporter. Leucine-responsive regulatory protein, Lrp, and protein Sestrin2 are intracellular L-leucine sensors that are induced to conformational change by binding of leucine. Lrp, a Escherichia coli protein, is a transcriptional regulator which transduces L-leucine information to the DNA and therefore activates/represses transcription of target genes. In this way, L-leucine effects transcription of tRNA, rRNA, amino acid catabolism genes, fimbria and transcription factors genes. Sestrin2 is a mammalian cytosolic protein that transfers L-leucine signal through mediator proteins to the terminal signal acceptor – protein complex mTORC1. mTORC1 is an architecture that includes mTOR protein kinase. Once mTOR has phosphorilated protein, actvity of a protein is activated or repressed. Phosphorilated proteins take part in lipid and protein biosynthesis reactions, energy metabolism and autophagy. In this way, L-leucine acts on the metabolic pathways of the cell.

• Keywords: signalna molekula; L-leucin
• Keywords (english): signal molecule; L-leucine
• Language: croatian
• URN:NBN: urn:nbn:hr:217:630639
• 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: 2018-01-03 09:05:42