Journal Article

Ca<sup>2+</sup> and Calmodulin Modulate DNA-Binding Activity of Maize Heat Shock Transcription Factor in Vitro

Bing Li, Hong-Tao Liu, Da-Ye Sun and Ren-Gang Zhou

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 45, issue 5, pages 627-634
Published in print May 2004 | ISSN: 0032-0781
Published online May 2004 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pch074
Ca2+ and Calmodulin Modulate DNA-Binding Activity of Maize Heat Shock Transcription Factor in Vitro

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DNA-binding activity of a maize heat shock transcription factor (HSF) was induced by heat shock of a whole cell extract at 44°C. Addition of the calcium ion chelator EGTA reduced the binding of the HSF to heat shock element (HSE) in vitro. Re-addition of CaCl2 to the sample pretreated with EGTA restored the ability of the HSF to bind to DNA. DNA-binding activity of the HSF was also induced by directly adding CaCl2 to a whole cell extract at non-heat-shock temperature, but not by MgCl2. During HS at 44°C, calmodulin (CaM) antagonists chlorpromazine (CPZ) and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W7) inhibited DNA-binding activity of the HSF in a concentration-dependent manner, but N-(6-aminohexyl)-1-naphthalenesulfonamide (W5), an inactive structural analogue of W7, did not. Addition of antiserum specific to CaM reduced the binding of the HSF to HSE. Re-addition of CaM to the sample pretreated with antiserum could restore the binding activity of the HSF. DNA-binding activity of the HSF was promoted by directly adding CaM to a whole cell extract at 44°C, but not by BSA. Moreover, at non-heat-shock temperature, DNA-binding activity of the HSF was also induced by directly adding CaM to a whole cell extract, but not by BSA. Our observations further confirm the role of Ca2+ in activation of the HSF in plant and provide the first example of the role of CaM in regulation of DNA-binding activity of the HSF. These results suggest that Ca2+ and CaM are involved in HSP gene expression likely through regulating the activity of the HSF.

Keywords: Keywords: Ca2+ — Calmodulin — DNA-binding activity — Heat shock transcription factor — Maize.; Abbreviations: CaM, calmodulin; CPZ, chlorpromazine; DTT, dithioreitol; HS, heat shock; HSE, heat shock element; HSF, heat shock transcription factor; HSPs, heat shock proteins; W7, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide; W5, N-(6-aminohexyl)-1-naphthalenesulfonamide.

Journal Article.  6047 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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