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Tim54p mediates the assembly of the AAA protease Yme1p
Author(s) -
Tienson Heather,
Hwang David K,
Leuenberger Danielle,
Claypool Steven,
Koehler Carla M
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a494
Subject(s) - protease , chemistry , microbiology and biotechnology , biology , biochemistry , enzyme
Tim54p is a component of the 300 kDa TIM22 complex of the yeast mitochondrial inner membrane and its specific role in mitochondrial biogenesis has not been elucidated. Tim54p contains one transmembrane domain from 38 to 55 and the N‐terminus inserts into the matrix with the bulk of the C‐terminus in the intermembrane space. [Delta]tim54 mitochondria contain lower levels of Tim22p, resulting in a decreased import of inner membrane substrates. However, a direct interaction between a precursor and Tim54p was not observed, suggesting that the observed decrease in import is a secondary effect of decreased Tim22p. Rather, yeast cells lacking Tim54p are petite‐negative because they are inviable on glucose media with ethidium bromide. [Delta]tim54 mitochondria had a lowered membrane potential, but maintained functional respiratory complexes and the mitochondrial genome. Loss of Tim54p was associated with aberrant nucleoid formation and defects in mitochondrial morphology, but they were a secondary defect. Subsequent analysis has shown that Tim54p mediates assembly of the intermembrane space protease Yme1p. Tim54p thus might coordinate mitochondrial assembly and turnover pathways. (H.T. and D.K.H. were supported by Ruth L Kirschstein National Research Service Award GM07185, S.M.C. was supported by the American Heart Association. This work was supported by grants from the NIH and Beckman Foundation.)