Ostermann, Joachim and Voos, Wolfgang and Kang, Pil-Jung and Craig, Elisabeth A. and Neupert, Walter and Pfanner, Nikolaus
Precursor proteins in transit through mitochondrial contact sites interact with hsp70 in the matrix.
In: FEBS Letters, Vol. 277, No. 1-2: pp. 281-284
We previously reported that hsp70 in the mitochondrial matrix (mt-hsp70 = Ssc1p) is required for import of precursor proteins destined for the matrix or intermembrane space. Here we show that mt-hsp70 is also needed for the import of mitochondrial inner membrane proteins. In particular, the precursor of ADP/ATP carrier that is known not to interact with hsp60 on its assembly pathway requires functional mt-hsp70 for import, suggesting a general role of mt-hsp70 in membrane translocation of precursors. Moreover, a precursor arrested in contact sites was specifically co-precipitated with antibodies directed against mt-hsp70. We conclude that mt-hsp70 is directly involved in the translocation of many, if not all, precursor proteins that are transported across the inner membrane.