AtBAG6, a novel calmodulin-binding protein, induces programmed cell death in yeast and plants.
Calmodulin (CaM) influences many cellular processes by interacting with various proteins. Here, we isolated AtBAG6, an Arabidopsis CaM-binding protein that contains a central BCL-2-associated athanogene (BAG) domain. In yeast and plants, overexpression of AtBAG6 induced cell death phenotypes consistent with programmed cell death (PCD). Recombinant AtBAG6 had higher affinity for CaM in the absence of free Ca2 + than in its presence. An IQ motif (IQXXXRGXXXR, where X denotes any amino-acid) was required for Ca2 +-independent CaM complex formation and single amino-acid changes within this motif abrogated both AtBAG6-activated CaM-binding and cell death in yeast and plants. A 134-amino-acid stretch, encompassing both the IQ motif and BAG domain, was sufficient to induce cell death. Agents generating oxygen radicals, which are known to be involved in plant PCD, specifically induced the AtBAG6 transcript. Collectively, these results suggest that AtBAG6 is a stress-upregulated CaM-binding protein involved in plant PCD.
Kang
C H
CH
Division of Applied Life Science (BK21 program) and Environmental Biotechnology National Core Research Center, Graduate School of Gyeongsang National University, Jinju 660-701, Korea.
Jung
W Y
WY
Kang
Y H
YH
Kim
J Y
JY
Kim
D G
DG
Jeong
J C
JC
Baek
D W
DW
Jin
J B
JB
Lee
J Y
JY
Kim
M O
MO
Chung
W S
WS
Mengiste
T
T
Koiwa
H
H
Kwak
S S
SS
Bahk
J D
JD
Lee
S Y
SY
Nam
J S
JS
Yun
D J
DJ
Cho
M J
MJ
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D017209:Apoptosis / Q000502:physiology*; D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D017343:Genes, Plant; D050883:HSC70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D014170:Transformation, Genetic; D020798:Two-Hybrid System Techniques
D029681:Arabidopsis Proteins; D002148:Calmodulin-Binding Proteins; D018744:DNA, Plant; D050883:HSC70 Heat-Shock Proteins; D011994:Recombinant Proteins