Import of Nuclear Encoded tRNA into Mitochondria

Yermovsky-Kammerer, Audra E.; Hajduk, Stephen L.

doi:10.1007/978-1-4757-4622-8_1

Cited by 2 publications

(1 citation statement)

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“…Previous studies have shown that mitochondria from kineto- plastid protozoa (Leishmania and trypanosomes) do not require cytoplasmic fractions to import tRNAs (12,19,25), implying that selectivity resides at the mitochondrial surface and not in soluble factors. This was borne out in the present instance by the ease with which a large number of import aptamers were selected: only four cycles of selection-amplification were necessary to achieve saturation of import efficiency by using a 16-mer library (Fig.…”

Section: Discussionmentioning

confidence: 97%

Mitochondrial RNA Import in Leishmania tropica: Aptamers Homologous to Multiple tRNA Domains That Interact Cooperatively or Antagonistically at the Inner Membrane

Bhattacharyya

Chatterjee

Adhya

2002

Molecular and Cellular Biology

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A large number of cytoplasmic tRNAs are imported into the kinetoplast-mitochondrion of Leishmania by a receptor-mediated process. To identify the sequences recognized by import receptors, mitochondria were incubated with a combinatorial RNA library. Repeated cycles of amplification of the imported sequences (SELEX) resulted in rapid selection of several import aptamers containing sequence motifs present in the anticodon arm, the D arm, the V-T region, and acceptor stem of known tRNAs, confirming or suggesting the presence of import signals in these domains. As predicted, truncated derivatives of tRNA Ile (UAU) containing the D arm or the V-T region were imported in vitro. Four aptamers were studied in detail. All were imported in vitro as well as in transiently transfected cells, using the same pathway as tRNA, but their individual import efficiencies were different. Two types of aptamers were discernible: the A arm and D arm homologues (type I), which were efficiently transferred across the inner mitochondrial membrane, and the V-T homologues (type II), which were not. Remarkably, subnanomolar concentrations of type I RNAs stimulated the entry of type II RNAs into the matrix, whereas type II RNAs inhibited inner membrane transfer of type I RNAs. Moreover, tRNA Tyr (GUA) and tRNA Ile (UAU) interacted with one another as type I and type II, respectively. Such cooperative and antagonistic interactions may allow the use of a limited number of receptors to recognize a large number of tRNAs of variable affinity and enable the maintenance of a properly balanced tRNA pool for mitochondrial translation.

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Section: Discussionmentioning

confidence: 97%