TY - JOUR
T1 - Tim54p connects inner membrane assembly and proteolytic pathways in the mitochondrion
AU - Hwang, David K.
AU - Claypool, Steven M.
AU - Leuenberger, Danielle
AU - Tienson, Heather L.
AU - Koehler, Carla M.
PY - 2007/9/24
Y1 - 2007/9/24
N2 - Tim54p, a component of the inner membrane TIM22 complex, does not directly mediate the import of inner membrane substrates but is required for assembly/ stability of the 300-kD TIM22 complex. In addition, Δtim54 yeast exhibit a petite-negative phenotype (also observed in yeast harboring mutations in the F1Fo ATPase, the ADP/ATP carrier, mitochondrial morphology components, or the i-AAA protease, Yme1p). Interestingly, other import mutants in our strain background are not petite-negative. We report that Tim54p is not involved in maintenance of mitochondrial DNA or mitochondrial morphology. Rather, Tim54p mediates assembly of an active Yme1p complex, after Yme1p is imported via the TIM23 pathway. Defective Yme1p assembly is likely the major contributing factor for the petite-negativity in strains lacking functional Tim54p. Thus, Tim54p has two independent functions: scaffolding/stability for the TIM22 membrane complex and assembly of Yme1p into a proteolytically active complex. As such, Tim54p links protein import, assembly, and turnover pathways in the mitochondrion.
AB - Tim54p, a component of the inner membrane TIM22 complex, does not directly mediate the import of inner membrane substrates but is required for assembly/ stability of the 300-kD TIM22 complex. In addition, Δtim54 yeast exhibit a petite-negative phenotype (also observed in yeast harboring mutations in the F1Fo ATPase, the ADP/ATP carrier, mitochondrial morphology components, or the i-AAA protease, Yme1p). Interestingly, other import mutants in our strain background are not petite-negative. We report that Tim54p is not involved in maintenance of mitochondrial DNA or mitochondrial morphology. Rather, Tim54p mediates assembly of an active Yme1p complex, after Yme1p is imported via the TIM23 pathway. Defective Yme1p assembly is likely the major contributing factor for the petite-negativity in strains lacking functional Tim54p. Thus, Tim54p has two independent functions: scaffolding/stability for the TIM22 membrane complex and assembly of Yme1p into a proteolytically active complex. As such, Tim54p links protein import, assembly, and turnover pathways in the mitochondrion.
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U2 - 10.1083/jcb.200706195
DO - 10.1083/jcb.200706195
M3 - Article
C2 - 17893242
AN - SCOPUS:34748833589
SN - 0021-9525
VL - 178
SP - 1161
EP - 1175
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 7
ER -