RBP38, a novel RNA-binding protein from trypanosomatid mitochondria, modulates RNA stability.
We describe here the isolation and characterization of a novel RNA-binding protein, RBP38, from Leishmania tarentolae mitochondria. This protein does not contain any known RNA-binding motifs and is highly conserved among the trypanosomatids, but no homologues were found in other organisms. Recombinant LtRBP38 binds single and double-stranded (ds) RNA substrates with dissociation constants in the 100 nM range, as determined by fluorescence polarization analysis. Downregulation of expression of the homologous gene, TbRBP38, in procyclic Trypanosoma brucei by using conditional dsRNA interference resulted in 80% reduction of steady-state levels of RNAs transcribed from both maxicircle and minicircle DNA. In organello pulse-chase labeling experiments were used to determine the stability of RNAs in mitochondria that were depleted of TbRBP38. The half-life of metabolically labeled RNA decreased from approximately 160 to approximately 60 min after depletion. In contrast, there was no change in transcriptional activity. These observations suggest a role of RBP38 in stabilizing mitochondrial RNA.
Sbicego
Sandro
S
Howard Hughes Medical Institute, University of California, Los Angeles, California 90095-1662, USA.
Alfonzo
Juan D
JD
Estévez
Antonio M
AM
Rubio
Mary Anne T
MA
Kang
Xuedong
X
Turck
Christoph W
CW
Peris
Marian
M
Simpson
Larry
L
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D017124:Conserved Sequence; D004926:Escherichia coli / Q000235:genetics; D005786:Gene Expression Regulation; D017125:Genes, Protozoan; D007891:Leishmania / Q000254:growth & development / Q000378:metabolism; D008928:Mitochondria / Q000737:chemistry*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012313:RNA / Q000378:metabolism*; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D016053:RNA, Protozoan / Q000032:analysis / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D012333:RNA, Messenger; D016053:RNA, Protozoan; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D012313:RNA