טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentAkerman Martin
SubjectSequence Analysis of Amino Acid Permease Genes from
Leishmania donovani
DepartmentDepartment of Biology
Supervisor Professor Emeritus Dan Zilberstein


Abstract

            Leishmania donovani are obligatory intracellular parasites that cycle between midgut of sand flies and phagolysosomes of mammalian macrophages. In sand flies they encounter amino acid rich environment to which they have adapted by obtaining high level of transport, specially of proline and alanine. Eight of the amino acid permease genes that mediate this process in Leishmania donovani have been recently cloned in our lab. In this work, the cloning process of two of the genes, AAP13LD and AAP15LD, is shown. Phylogenetic analysis of the amino acid permease genes from Leishmania donovani indicated that seven of them (AAPLD 1-3, AAP8LD, AAP11LD, AAP13LD and AAP15LD) belong to the ATF-1 super family (Pfam 01490). One (AAP10LD) belong to the APC (pfam 00324). Using these sequences as well as known and characterized amino acid permease genes from all kingdoms, a training set was established and used to search for motifs, using the MEME motif discovery tool. This study revealed two motifs that are specific to the genus Leishmania (L1 and L2 motifs), four to the family trypanosomatids (T 1-4 motifs) and a single motif that is common between trypanosomatids and mammalian A1 and N permeases (N motif). Most of these motifs are clustered in two regions of 50-60 amino acids. Phylogenic analyses indicated close relationship between the L. donovani and Trypanosoma. brucei amino acid permeases. Interestingly, AAPLD genes that belong to ATF-1 display closer phylogenic relationship to mammalian transporters than plant or protist transporters, although most of the known Leishmania genes are phylogenically closer to plants.