The α-subunit of Leishmania F1 ATP synthase hydrolyzes ATP in presence of tRNA

Goswami, Srikanta ; Adhya, Samit (2006) The α-subunit of Leishmania F1 ATP synthase hydrolyzes ATP in presence of tRNA Journal of Biological Chemistry, 281 (28). pp. 18914-18917. ISSN 0021-9258

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Import of tRNAs into the mitochondria of the kinetoplastid protozoon Leishmania requires the tRNA-dependent hydrolysis of ATP leading to the generation of membrane potential through the pumping of protons. Subunit RIC1 of the inner membrane RNA import complex is a bi-functional protein that is identical to the α -subunit of F1F0 ATP synthase and specifically binds to a subset (Type I) of importable tRNAs. We show that recombinant, purified RIC1 is a Type I tRNA-dependent ATP hydrolase. The activity was insensitive to oligomycin, sensitive to mutations within the import signal of the tRNA, and required the cooperative interaction between the ATP-binding and C-terminal domains of RIC1. The ATPase activity of the intact complex was inhibited by anti-RIC1 antibody, while knockdown of RIC1 in Leishmania tropica resulted in deficiency of the tRNA-dependent ATPase activity of the mitochondrial inner membrane. Moreover, RIC1 knockdown extracts failed to generate a membrane potential across reconstituted proteoliposomes, as shown by a rhodamine 123 uptake assay, but activity was restored by adding back purified RIC1. These observations identify RIC1 as a novel form of the F1 ATP synthase α-subunit that acts as the major energy transducer for tRNA import.

Item Type:Article
Source:Copyright of this article belongs to American Society for Biochemistry and Molecular Biology.
ID Code:12048
Deposited On:09 Nov 2010 11:39
Last Modified:16 May 2016 21:27

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