Disruption of the M80-Fe ligation stimulates the translocation of cytochrome c to the cytoplasm and nucleus in nonapoptotic cells.
Native cytochrome c (cyt c) has a compact tertiary structure with a hexacoordinated heme iron and functions in electron transport in mitochondria and apoptosis in the cytoplasm. However, the possibility that protein modifications confer additional functions to cyt c has not been explored. Disruption of methionine 80 (M80)-Fe ligation of cyt c under nitrative stress has been reported. To model this alteration and determine if it confers new properties to cyt c, a cyt c mutant (M80A) was constitutively expressed in cells. M80A-cyt c has increased peroxidase activity and is spontaneously released from mitochondria, translocating to the cytoplasm and nucleus in the absence of apoptosis. Moreover, M80A models endogenously nitrated cyt c because nitration of WT-cyt c is associated with its translocation to the cytoplasm and nucleus. Further, M80A cyt c may up-regulate protective responses to nitrative stress. Our findings raise the possibility that endogenous protein modifications that disrupt the M80-Fe ligation (such as tyrosine nitration) stimulate nuclear translocation and confer new functions to cyt c in nonapoptotic cells.
Godoy
Luiz C
LC
Department of Medicine and Cellular Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
Muñoz-Pinedo
Cristina
C
Castro
Laura
L
Cardaci
Simone
S
Schonhoff
Christopher M
CM
King
Michael
M
Tórtora
Verónica
V
Marín
Mónica
M
Miao
Qian
Q
Jiang
Jian Fei
JF
Kapralov
Alexandr
A
Jemmerson
Ronald
R
Silkstone
Gary G
GG
Patel
Jinal N
JN
Evans
James E
JE
Wilson
Michael T
MT
Green
Douglas R
DR
Kagan
Valerian E
VE
Radi
Rafael
R
Mannick
Joan B
JB
D017209:Apoptosis; D002467:Cell Nucleus / Q000201:enzymology*; D002478:Cells, Cultured; D045304:Cytochromes c / Q000235:genetics / Q000378:metabolism*; D003593:Cytoplasm / Q000201:enzymology*; D005455:Fluorescent Antibody Technique; D049452:Green Fluorescent Proteins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D007501:Iron / Q000378:metabolism*; D034741:RNA, Small Interfering
D034741:RNA, Small Interfering; D049452:Green Fluorescent Proteins; D045304:Cytochromes c; D007501:Iron