Unit:
Faculty of MedicineLibrary of the School of Health Sciences
Author:
Tziouvara Olympia-Paraskevi
Dissertation committee:
Ευθυμία Μπάσδρα, Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Χαραλαμπία Μπολέτη, Διευθύντρια Ερευνών, Τμήμα Μικροβιολογίας, Ελληνικό Ινστιτούτο Παστέρ
Σάββας Χριστοφορίδης, Καθηγητής, Τμήμα Ιατρικής, Πανεπιστήμιο Ιωαννίνων
Μαριάννα (Μαρία) Νταλαμάγκα, Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Αγγελική Παπαπαναγιώτου, Aναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Χριστίνα Πιπερη, Aναπληρώτρια Καθηγήτρια, Ιατρική Σχολή, ΕΚΠΑ
Χρήστος Αδαμόπουλος, Επίκουρος Καθηγητής, Ιατρική Σχολή, ΕΚΠΑ
Original Title:
Φωσφατάσες φωσφοϊνοσιτιδίων και πρωτεΐνες με υποτομείς πρόσδεσης σε φωσφοϊνοσιτίδια του παρασίτου Leishmania: Χαρακτηρισμός δύο αντιπροσωπευτικών μορίων και μελέτη του ρόλου τους στον κύκλο ζωής του παρασίτου και στη λοίμωξη του θηλαστικού ξενιστή με το παράσιτο.
Translated title:
Phosphoinositide phosphatases and phosphoinositide binding proteins from Leishmania parasites: characterizations of two representative molecules and their involvement in the parasite's life cycle and the infection of the mammalian host
Summary:
Leishmania parasites cause vector-borne diseases known as Leishmaniases, with L. donovani causing visceral leishmaniasis, the most severe form of the disease. During their biological cycle, Leishmania parasites undergo distinct developmental transitions that involve dramatic changes in cell size and shape, flagellum reassembly, and membrane and cytoskeleton remodeling. Phosphoinositide signaling and metabolism are likely to play central roles in these processes. We identified the LDBPK_220120 gene as the L. donovani ortholog of LmjF.22.0250 from L. major that encodes a Dual Specificity P-Tyr and monophosphorylated [PtdIns(3)P and PtdIns(4)P] PI phosphatase. We named the gene product LDBPK_220120.1 as LdTyrPIP_22 (Leishmania donovani Tyrosine PI Phosphatase). Biochemical and immunofluorescence studies confirmed its expression in several intracellular sites in the cell body of L. donovani promastigotes and amastigotes, and in the flagellum. A temperature and pH shift from 25 °C to 37 °C and from pH 7 to 5.5, induced a pronounced recruitment of LdTyrPIP_22 epitopes to the flagellar pocket and a redistribution around the nucleus. These results suggest possible role(s) for this P-Tyr/PI phosphatase in the regulation of processes initiated or upregulated by this temperature/pH shift that contribute to the parasite’s developmental transition from Metacyclic prompastigotes (MPs) to amastigotes inside the mammalian host macrophages.Sorting nexins (SNXs) are a group of eukaryotic proteins that play crucial roles in intracellular trafficking, endosome dynamics, protein sorting, and autophagy. They contain a PX domain that binds to specific phosphoinositide (PI) phospholipids and have additional structural domains, such as BAR and FERM, that confer diverse functions. Despite their evolutionary conservation, SNXs are poorly studied in protists. Herein, is reported the identification and characterization of the first SNX identified in Leishmania protozoan parasites, named LdSNXi. In silico analysis revealed that LdSNXi belongs to the SNX-BAR subfamily, with a PX domain at its N-terminal half and a BAR domain at its C-terminal half. Biochemical and immunofluorescence studies confirmed its expression and localization in L. donovani promastigotes and axenic amastigotes. Its localization was also studied in transfected human HeLa cells. Sequence and structural analysis revealed high homology between LdSNXi and human SNX2. Investigation of protein-protein interactions predicted LdSNXi putative molecular partners and their functions in Leishmania protists.
Main subject category:
Health Sciences
Keywords:
Leishmaniasis, Phosphoinositides, Phosphatase, Sorting nexin
Number of references:
249
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