Crystal structure of Arabidopsis thaliana calmodulin7 and insight into its mode of DNA binding

• Published in: FEBS letters 2016-09, Vol.590 (17), p.3029-3039
• Main Authors: Kumar, Sanjeev, Mazumder, Mohit, Gupta, Nisha, Chattopadhyay, Sudip, Gourinath, Samudrala
• Format: Article
• Language: English
• Subjects: Arabidopsis - chemistry; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Calmodulin - chemistry; Calmodulin - genetics; Calmodulin - metabolism; CaM; Crystallography, X-Ray; DNA - chemistry; DNA - metabolism; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Gene Expression Regulation, Plant; molecular modeling; Protein Binding - genetics; Protein Conformation; protein crystallization; protein–DNA interaction
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1002/1873-3468.12349

Calmodulin (CaM) is a Ca2+ sensor that participates in several cellular signaling cascades by interacting with various targets, including DNA. It has been shown that Arabidopsis thaliana CaM7 (AtCaM7) interacts with Z‐box DNA and functions as a transcription factor [Kushwaha R et al. (2008) Plant Cell 20, 1747–1759; Abbas N et al. (2014) Plant Cell 26, 1036–1052]. The crystal structure of AtCaM7, and a model of the AtCAM7‐Z‐box complex suggest that Arg‐127 determines the DNA‐binding ability by forming crucial interactions with the guanine base. We validated the model using biolayer interferometry, which confirmed that AtCaM7 interacts with Z‐box DNA with high affinity. In contrast, the AtCaM2/3/5 isoform does not show any binding, although it differs from AtCaM7 by only a single residue.