Binding of the maize cytosolic Hsp70 to calmodulin, and identification of calmodulin-binding site in Hsp70

• Published in: Plant and cell physiology Vol. 41; no. 6; pp. 804 - 810
• Main Authors: Sun, X.T. (Hebei Academy of Agricultural Sciences, Shijiazhuang (China)), Li, B, Zhou, G.M, Tang, W.Q, Bai, J, Sun, D.Y, Zhou, R.G
• Format: Journal Article
• Language: English
• Published: Japan Plant and Cell Physiology 01-06-2000
• Subjects: Amino Acid Sequence; BINDING PROTEINS; Binding Sites; CALCIO; CALCIUM; Calcium - metabolism; CALMODULIN; Calmodulin - chemistry; Calmodulin - genetics; Calmodulin - metabolism; Calmodulin-binding protein; CALMODULINA; CALMODULINE; CITOPLASMA; CYTOPLASM; CYTOPLASME; Cytosol - metabolism; Hsp70; HSP70 Heat-Shock Proteins - chemistry; HSP70 Heat-Shock Proteins - metabolism; Kinetics; Molecular Sequence Data; Peptide Fragments - chemical synthesis; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Plant Leaves; PROTEINAS AGLUTINANTES; PROTEINE DE LIAISON; Recombinant Proteins - metabolism; Signal transduction; Solanum tuberosum - genetics; Solanum tuberosum - metabolism; ZEA MAYS; Zea mays - metabolism
• ISSN: 0032-0781; 1471-9053
• DOI: 10.1093/pcp/41.6.804

Using a gel-overlay technique of biotinylated calmodulin (CaM), we showed that maize cytosolic Hsp70 protein could bind to CaM in the presence of 1 mM CaCl2. The purified maize cytosolic Hsp70 inhibited the activity of CaM-dependent NADK in a concentrationdependent manner. A synthetic peptide, which possesses the 21 amino acid sequence, PRALRRLRTACERAKRTLSST, at positions 261–281 in maize cytosolic Hsp70, could associate with CaM in the presence of 1 mM calcium. The synthetic peptide inhibited CaM-dependent NADK activity and PDE activity. This indicates that the 21-amino acid sequence at positions 261–281 is the CaM-binding site. The binding of CaM to Hsp70 inhibited the ATPase activity of Hsp70. The possible regulator function of Hsp70 in cell signaling events in response to heat stress is discussed.