Mutations in a tRNA Import Signal Define Distinct Receptors at the Two Membranes of Leishmania Mitochondria
AUTOR(ES)
Bhattacharyya, Subhendra Nath
FONTE
American Society for Microbiology
RESUMO
Nucleus-encoded tRNAs are selectively imported into the mitochondrion of Leishmania, a kinetoplastid protozoan. An oligoribonucleotide constituting the D stem-loop import signal of tRNATyr(GUA) was efficiently transported into the mitochondrial matrix in organello as well as in vivo. Transfer through the inner membrane could be uncoupled from that through the outer membrane and was resistant to antibody against the outer membrane receptor TAB. A number of mutations in the import signal had differential effects on outer and inner membrane transfer. Some mutants which efficiently traversed the outer membrane were unable to enter the matrix. Conversely, restoration of the loop-closing GC pair in reverse resulted in reversion of transfer through the inner, but not the outer, membrane, and binding of the RNA to the inner membrane was restored. These experiments indicate the presence at the two membranes of receptors with distinct specificities which mediate stepwise transfer into the mitochondrial matrix. The combination of oligonucleotide mutagenesis and biochemical fractionation may provide a general tool for the identification of tRNA transport factors.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=86294Documentos Relacionados
- Allosteric regulation of tRNA import: interactions between tRNA domains at the inner membrane of Leishmania mitochondria
- In Vitro Import of a Nuclearly Encoded tRNA into Mitochondria of Solanum tuberosum
- Mitochondrial RNA Import in Leishmania tropica: Aptamers Homologous to Multiple tRNA Domains That Interact Cooperatively or Antagonistically at the Inner Membrane
- “Ping-Pong” Interactions between Mitochondrial tRNA Import Receptors within a Multiprotein Complex
- A methionine tRNA gene from lupine mitochondria.