Molecular and genetic evidence for the key role of AtCaM3 in heat-shock signal transduction in Arabidopsis.
Heat shock (HS) is a common form of stress suffered by plants. It has been proposed that calmodulin (CaM) is involved in HS signal transduction, but direct evidence has been lacking. To investigate the potential regulatory function of CaM in the HS signal transduction pathway, T-DNA knockout mutants for AtCaM2, AtCaM3, and AtCaM4 were obtained and their thermotolerance tested. Of the three knockout mutant plants, there were no differences compared with wild-type plants under normal conditions. However, the AtCaM3 knockout mutant showed a clear reduction in thermotolerance after heat treatment at 45 degrees C for 50 min. Overexpression of AtCaM3 in either the AtCaM3 knockout or wild-type background significantly rescued or increased the thermotolerance, respectively. Results from electrophoretic mobility-shift assays, real-time quantitative reverse transcription-polymerase chain reaction, and western-blot analyses revealed that, after HS, the DNA-binding activity of HS transcription factors, mRNA transcription of HS protein genes, and accumulation of HS protein were down-regulated in the AtCaM3 knockout mutant and up-regulated in the AtCaM3-overexpressing transgenic lines. Taken together, these results suggest that endogenous AtCaM3 is a key component in the Ca2+-CaM HS signal transduction pathway.
Zhang
Wei
W
Institute of Molecular Cell Biology, Hebei Normal University, Shijiazhuang 050016, China.
Zhou
Ren-Gang
RG
Gao
Ying-Jie
YJ
Zheng
Shu-Zhi
SZ
Xu
Peng
P
Zhang
Su-Qiao
SQ
Sun
Da-Ye
DY
D000222:Adaptation, Physiological; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002147:Calmodulin / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000235:genetics; D018744:DNA, Plant / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D018869:Heat-Shock Response; D016254:Mutagenesis, Insertional; D050505:Mutant Proteins / Q000302:isolation & purification; D009154:Mutation / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D036226:Seedlings / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013696:Temperature; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014170:Transformation, Genetic
D029681:Arabidopsis Proteins; C541275:CaM3 protein, Arabidopsis; D002147:Calmodulin; D004269:DNA, Bacterial; D018744:DNA, Plant; D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D050505:Mutant Proteins; D010940:Plant Proteins; C036483:T-DNA; D014157:Transcription Factors