Progress in the participation of Ca2+-calmodulin in heat shock signal transduction

A novel heat shock (HS) signal transduction pathway in plants for the participation of Ca2+-calmodulin (CaM) in HS signal transduction was identified. HS induces a rapid increase in intracellular free calcium ion levels ([Ca2+](i)), and the involvement of phospholipase C-inositol 1,4,5-trisphosphate is one of the factors leading to elevation in [Ca2+](i) induced by HS. HS also increases the expression of the CaM gene and the accumulation of the CaM protein. The CaM isoform, AtCaM3, in Arabidopsis is a key member in the HS signal transduction pathway. AtCaM3 regulates the activity of CaM-binding protein kinase (AtCBK3) or protein phosphatase (AtPP7), promoting the activation of the HS transcription factor, Lambda tHSF Lambda 1a, by phosphorylation/dephosphorylation and the expression of heat shock protein genes, then improving heat tolerance in plants. (C) 2009 National Natural Science Foundation of China and Chinese Academy of Sciences. Published by Elsevier Limited and Science in China Press. All rights reserved.