An RNA-binding respiratory component mediates import of type II tRNAs into Leishmania mitochondria
Metadata of CSIR Papers
View Archive Info| Field | Value | |
| Title |
An RNA-binding respiratory component mediates import of type II tRNAs into Leishmania mitochondria
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| Creator |
Chatterjee, S
Home, P Mukherjee, S Mahata, B Goswami, S Dhar, G Adhya, S |
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| Subject |
Biochemistry & Molecular Biology
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| Description |
Transport of tRNAs across the inner mitochondrial membrane of the kinetoplastid protozoon Leishmania requires interactions with specific binding proteins (receptors) in a multi-subunit complex. The allosteric model of import regulation proposes cooperative and antagonistic interactions between two or more receptors with binding specificities for distinct tRNA families (types I and II, respectively). To identify the type II receptor, the gene encoding RIC8A, a subunit of the complex, was cloned. The C-terminal region of RIC8A is homologous to subunit 6b of ubiquinol cytochrome c reductase (respiratory complex III), while the N-terminal region has intrinsic affinity for type II, but not for type I, tRNAs. RIC8A is shared by the import complex and complex III, indicating its bi-functionality, but is assembled differently in the two complexes. Knockdown of RIC8A in Leishmania lowered the mitochondrial content of type II tRNAs but raised that of type I tRNAs, with downstream effects on mitochondrial translation and respiration, and cell death. In RIC8A knockdown cells, a subcomplex was formed that interacted with type I tRNA, but the negative regulation by type II tRNA was lost. Mitochondrial extracts from these cells were defective for type II, but not type I, import; import and regulation were restored by purified RIC8A. These results provide evidence for the relevance of allosteric regulation in vivo and indicate that acquisition of new tRNA-binding domains by ancient respiratory components have played a key role in the evolution of mitochondrial tRNA import.
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| Publisher |
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INCBETHESDA9650 ROCKVILLE PIKE, BETHESDA, MD 20814-3996 USA
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| Date |
2011-09-20T12:12:09Z
2011-09-20T12:12:09Z 2006 |
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| Type |
Article
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| Identifier |
JOURNAL OF BIOLOGICAL CHEMISTRY
0021-9258 http://hdl.handle.net/123456789/14148 |
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| Language |
English
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