The C-terminal region of TIM17 links the outer and inner mitochondrial membranes in Arabidopsis and is essential for protein import.
The translocase of the inner membrane 17 (AtTIM17-2) protein from Arabidopsis has been shown to link the outer and inner mitochondrial membranes. This was demonstrated by several approaches: (i) In vitro organelle import assays indicated the imported AtTIM17-2 protein remained protease accessible in the outer membrane when inserted into the inner membrane. (ii) N-terminal and C-terminal tagging indicated that it was the C-terminal region that was located in the outer membrane. (iii) Antibodies raised to the C-terminal 100 amino acids recognize a 31-kDa protein from purified mitochondria, but cross-reactivity was abolished when mitochondria were protease-treated to remove outer membrane-exposed proteins. Antibodies to AtTIM17-2 inhibited import of proteins via the general import pathway into outer membrane-ruptured mitochondria, but did not inhibit protein import via the carrier import pathway. Together these results indicate that the C-terminal region of AtTIM17-2 is exposed on the outer surface of the outer membrane, and the C-terminal region is essential for protein import into mitochondria.
Murcha
Monika W
MW
Plant Molecular Biology Group, School of Biomedical and Chemicals Sciences, University of Western Australia, 35 Stirling Highway, Crawley 6009, Western Australia, Australia.
Elhafez
Dina
D
Millar
A Harvey
AH
Whelan
James
J
D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000276:immunology / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000276:immunology / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D010447:Peptide Hydrolases / Q000378:metabolism; D021381:Protein Transport / Q000276:immunology / Q000502:physiology
D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; C501430:TIM17 protein, Arabidopsis; D010447:Peptide Hydrolases