Dataset Information

Novel role of ATPase subunit C targeting peptides beyond mitochondrial protein import.

ABSTRACT: In mammals, subunit c of the F(1)F(0)-ATP synthase has three isoforms (P1, P2, and P3). These isoforms differ by their cleavable mitochondrial targeting peptides, whereas the mature peptides are identical. To investigate this apparent genetic redundancy, we knocked down each of the three subunit c isoform by RNA interference in HeLa cells. Silencing any of the subunit c isoforms individually resulted in an ATP synthesis defect, indicating that these isoforms are not functionally redundant. We found that subunit c knockdown impaired the structure and function of the mitochondrial respiratory chain. In particular, P2 silencing caused defective cytochrome oxidase assembly and function. Because the expression of exogenous P1 or P2 was able to rescue the respective silencing phenotypes, but the two isoforms were unable to cross-complement, we hypothesized that their functional specificity resided in their targeting peptides. In fact, the expression of P1 and P2 targeting peptides fused to GFP variants rescued the ATP synthesis and respiratory chain defects in the silenced cells. Our results demonstrate that the subunit c isoforms are nonredundant, because they differ functionally by their targeting peptides, which, in addition to mediating mitochondrial protein import, play a yet undiscovered role in respiratory chain maintenance.

SUBMITTER: Vives-Bauza C

PROVIDER: S-EPMC2801706 | biostudies-literature | 2010 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Novel role of ATPase subunit C targeting peptides beyond mitochondrial protein import.

Vives-Bauza Cristofol C Magrané Jordi J Andreu Antoni L AL Manfredi Giovanni G

Molecular biology of the cell 20091104 1

In mammals, subunit c of the F(1)F(0)-ATP synthase has three isoforms (P1, P2, and P3). These isoforms differ by their cleavable mitochondrial targeting peptides, whereas the mature peptides are identical. To investigate this apparent genetic redundancy, we knocked down each of the three subunit c isoform by RNA interference in HeLa cells. Silencing any of the subunit c isoforms individually resulted in an ATP synthesis defect, indicating that these isoforms are not functionally redundant. We fo ...[more]

PMID: 19889836

Similar Datasets

Project description:BackgroundThe translocase of the mitochondrial inner membrane (TIM) imports most of the nucleus-encoded proteins that are destined for the matrix, inner membrane (IM) and the intermembrane space (IMS). Trypanosoma brucei, the infectious agent for African trypanosomiasis, possesses a unique TIM complex consisting of several novel proteins in association with a relatively conserved protein TbTim17. Tandem affinity purification of the TbTim17 protein complex revealed TbTim54 as a potential component of this complex.ResultsTbTim54, a trypanosome-specific IMS protein, is peripherally associated with the IM and is present in a protein complex slightly larger than the TbTim17 complex. TbTim54 knockdown (KD) reduced the import of TbTim17 and compromised the integrity of the TbTim17 complex. TbTim54 KD inhibited the in vitro mitochondrial import and assembly of the internal signal-containing mitochondrial carrier proteins MCP3, MCP5 and MCP11 to a greater extent than TbTim17 KD. Furthermore, TbTim54 KD, but not TbTim17 KD, significantly hampered the mitochondrial targeting of ectopically expressed MCP3 and MCP11. These observations along with our previous finding that the mitochondrial import of N-terminal signal-containing proteins like cytochrome oxidase subunit 4 and MRP2 was affected to a greater extent by TbTim17 KD than TbTim54 KD indicating a substrate-specificity of TbTim54 for internal-signal containing mitochondrial proteins. In other organisms, small Tim chaperones in the IMS are known to participate in the translocation of MCPs. We found that TbTim54 can directly interact with at least two of the six known small TbTim proteins, TbTim11 and TbTim13, as well as with the N-terminal domain of TbTim17.ConclusionTbTim54 interacts with TbTim17. It also plays a crucial role in the mitochondrial import and complex assembly of internal signal-containing IM proteins in T. brucei.SignificanceWe are the first to characterise TbTim54, a novel TbTim that is involved primarily in the mitochondrial import of MCPs and TbTim17 in T. brucei.

Dataset Information

Novel role of ATPase subunit C targeting peptides beyond mitochondrial protein import.

Publications

Novel role of ATPase subunit C targeting peptides beyond mitochondrial protein import.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets