Functions and cellular localization of cysteine desulfurase and selenocysteine lyase in Trypanosoma brucei.
Nfs-like proteins have cysteine desulfurase (CysD) activity, which removes sulfur (S) from cysteine, and provides S for iron-sulfur cluster assembly and the thiolation of tRNAs. These proteins also have selenocysteine lyase activity in vitro, and cleave selenocysteine into alanine and elemental selenium (Se). It was shown previously that the Nfs-like protein called Nfs from the parasitic protist Trypanosoma brucei is a genuine CysD. A second Nfs-like protein is encoded in the nuclear genome of T. brucei. We called this protein selenocysteine lyase (SCL) because phylogenetic analysis reveals that it is monophyletic with known eukaryotic selenocysteine lyases. The Nfs protein is located in the mitochondrion, whereas the SCL protein seems to be present in the nucleus and cytoplasm. Unexpectedly, downregulation of either Nfs or SCL protein leads to a dramatic decrease in both CysD and selenocysteine lyase activities concurrently in the mitochondrion and the cytosolic fractions. Because loss of Nfs causes a growth phenotype but loss of SCL does not, we propose that Nfs can fully complement SCL, whereas SCL can only partially replace Nfs under our growth conditions.
Poliak
Pavel
P
Biology Centre, Institute of Parasitology and Faculty of Science, University of South Bohemia, Ceské Budejovice (Budweis), Czech Republic.
Van Hoewyk
Douglas
D
Oborník
Miroslav
M
Zíková
Alena
A
Stuart
Kenneth D
KD
Tachezy
Jan
J
Pilon
Marinus
M
Lukes
Julius
J
D000818:Animals; D013437:Carbon-Sulfur Lyases / Q000235:genetics / Q000378:metabolism*; D002451:Cell Compartmentation; D003600:Cytosol / Q000201:enzymology; D017125:Genes, Protozoan; D008190:Lyases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000201:enzymology; D010802:Phylogeny; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D014346:Trypanosoma brucei brucei / Q000201:enzymology* / Q000235:genetics
D015800:Protozoan Proteins; D012333:RNA, Messenger; D016053:RNA, Protozoan; D008190:Lyases; D013437:Carbon-Sulfur Lyases; C080546:cysteine desulfurase; C034278:selenocysteine lyase