Identification of Leishmania selenoproteins and SECIS element.
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 Leishmania major and Leishmania infantum, the incorporation of (75)Se into Leishmania proteins, the occurrence of selenocysteine-tRNA (tRNA (sec) (uca)) in both Leishmania and Trypanosoma and in addition the finding of all genes necessary for selenocysteine synthesis such as SELB, SELD, PSTK and SECp43. As in other eukaryotes, the Kinetoplastids 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.
Cassago
A
A
Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-590 São Carlos, SP, Brazil.
Rodrigues
E M
EM
Prieto
E L
EL
Gaston
K W
KW
Alfonzo
J D
JD
Iribar
M P
MP
Berry
M J
MJ
Cruz
A K
AK
Thiemann
O H
OH
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016054:DNA, Protozoan / Q000235:genetics; D007891:Leishmania / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D015800:Protozoan Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D016053:RNA, Protozoan / Q000737:chemistry / Q000235:genetics; D012345:RNA, Transfer, Amino Acid-Specific / Q000737:chemistry / Q000235:genetics; D051140:Selenoproteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D016054:DNA, Protozoan; D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D012345:RNA, Transfer, Amino Acid-Specific; D051140:Selenoproteins; C036928:tRNA, selenocysteine-