An assembled complex IV maintains the stability and activity of complex I in mammalian mitochondria.
In the mammalian mitochondrial electron transfer system, the majority of electrons enter at complex I, go through complexes III and IV, and are finally delivered to oxygen. Previously we generated several mouse cell lines with suppressed expression of the nuclearly encoded subunit 4 of complex IV. This led to a loss of assembly of complex IV and its defective function. Interestingly, we found that the level of assembled complex I and its activity were also significantly reduced, whereas levels and activity of complex III were normal or up-regulated. The structural and functional dependence of complex I on complex IV was verified using a human cell line carrying a nonsense mutation in the mitochondrially encoded complex IV subunit 1 gene. Our work documents that, although there is no direct electron transfer between them, an assembled complex IV helps to maintain complex I in mammalian cells.
Li
Youfen
Y
Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA.
D'Aurelio
Marilena
M
Deng
Jian-Hong
JH
Park
Jeong-Soon
JS
Manfredi
Giovanni
G
Hu
Peiqing
P
Lu
Jianxin
J
Bai
Yidong
Y
D000818:Animals; D002460:Cell Line; D042967:Electron Transport Complex I / Q000502:physiology*; D003576:Electron Transport Complex IV / Q000502:physiology*; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference
D021122:Protein Subunits; D003576:Electron Transport Complex IV; D042967:Electron Transport Complex I