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  • The calmodulin-like protein CML43 functions as a salicylic-acid-inducible root-specific Ca(2+) sensor in Arabidopsis.

The calmodulin-like protein CML43 functions as a salicylic-acid-inducible root-specific Ca(2+) sensor in Arabidopsis.

The Biochemical journal (2013-10-10)
Kyle W Bender, Stephanie Dobney, Adenike Ogunrinde, David Chiasson, Robert T Mullen, Howard J Teresinski, Prabhjeet Singh, Kim Munro, Steven P Smith, Wayne A Snedden
ABSTRACT

Many signalling pathways in plants are regulated by the second messenger calcium (Ca(2+)). In the standard model, Ca(2+)-sensor proteins, such as CaM (calmodulin), detect Ca(2+) signals and subsequently regulate downstream targets to advance the signal transduction cascade. In addition to CaM, plants possess many CMLs (CaM-like proteins) that are predicted to function as Ca(2+) sensors, but which remain largely uncharacterized. In the present study, we examined the biochemical properties, subcellular localization and tissue-specific distribution of Arabidopsis CML43. Our data indicate that CML43 displays characteristics typical of Ca(2+) sensors, including high-affinity Ca(2+) binding, conformational changes upon Ca(2+) binding that expose hydrophobic regions and stabilization of structure in the presence of Mg(2+) or Ca(2+). In vivo localization analysis demonstrates that CML43 resides in cytosolic and nuclear compartments. Transgenic plants expressing a CML43:GUS (β-glucoronidase) promoter reporter gene revealed that CML43 promoter activity is restricted almost exclusively to root tips under normal growth conditions. GUS reporter activity in these transgenic plants was strongly increased when exposed to the defence compound SA (salicylic acid). Furthermore, immunoblot analysis revealed that the CML43 protein accumulates following treatment with SA. Collectively, our findings suggest that CML43 functions as a Ca(2+) sensor in root tips during both normal growth and plant immune response.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Salicylic acid, ACS reagent, ≥99.0%
Supelco
Salicylic acid, Pharmaceutical Secondary Standard; Certified Reference Material
Sigma-Aldrich
Salicylic acid, suitable for plant cell culture
Sigma-Aldrich
Salicylic acid, ≥99%, FG
Sigma-Aldrich
Salicylic acid, puriss. p.a., ≥99.0% (T)
Sigma-Aldrich
Salicylic acid, BioXtra, ≥99.0%
Sigma-Aldrich
Salicylic acid, meets analytical specification of Ph. Eur., BP, USP, 99.5-100.5% (calc. to the dried substance)
Sigma-Aldrich
Salicylic acid, ReagentPlus®, ≥99%
Supelco
Salicylic acid, certified reference material, TraceCERT®
Salicylic acid, European Pharmacopoeia (EP) Reference Standard
Supelco
Salicylic acid, 1.0 mg/mL in acetonitrile, ampule of 1 mL, certified reference material, Cerilliant®