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Identification of Leishmania selenoproteins and SECIS element.
Rodrigues, EM 1; Cassago, A 1; Prieto, EL1; Gaston, KW3,5; Alfonzo,JD3,4,5, Iribar, MP2; Cruz, AK2; Thiemann, OH1.
1 Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-590, São Carlos, SP, Brazil
2 Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos. Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, 14049-900, Ribeirão Preto, SP, Brazil
3 Department of Microbiology, 4 Ohio State Biochemistry program and the 5 Ohio State University RNA Group. The Ohio State University, Columbus, Ohio 43210, USA.
elisandra_usp@hotmail.com
Selenoproteins result from the incorporation of selenocysteine (Sec-U) at an UGA-stop codon positioned within a gene's open reading frame and directed by selenocysteine insertion sequence (SECIS) elements. Although the selenocysteine incorporation pathway has been identified in a wide range of organisms it has not yet been reported in the Kinetoplastida Leishmania and Trypanosoma. Here we present evidence consistent with the presence of a selenocysteine biosynthetic pathway in kinetoplastida. These include the existence of SECIS containing coding sequences in L. major and L. infantum, the occurrence of selenocysteine-tRNA (tRNAsecuca) in both Leishmania and Trypanosoma and in addition the finding of all other genes necessary for selenocysteine synthesis such as SelB, SelD, PSTK and SECp43. As in other eukaryotes, the Kinetoplastida have no identifiable SelA homologue. To our knowledge this is the first report on the identification of selenocysteine insertion machinery in Kinetoplastida, more specifically in Leishmania, at the sequence level.
Acknowledgements: FAPESP, CNPq, CAPES
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