Genes Encoding Calmodulin-binding Proteins in the Arabidopsis Genome

• Published in: The Journal of biological chemistry Vol. 277; no. 12; pp. 9840 - 9852
• Main Authors: Reddy, Vaka S., Ali, Gul S., Reddy, Anireddy S N.
• Format: Journal Article
• Language: English
• Published: Legacy CDMS American Society for Biochemistry and Molecular Biology 22.03.2002
• Subjects: Amino Acid Sequence; Arabidopsis - genetics; Arabidopsis thaliana; Calcium - metabolism; Calmodulin - metabolism; Calmodulin-binding protein; Calmodulin-Binding Proteins - genetics; Databases as Topic; DNA, Complementary - metabolism; Gene Expression Regulation, Plant; Gene Library; Genome, Plant; Life Sciences (General); Models, Genetic; Molecular Sequence Data; Mutation; Phylogeny; Protein Binding; Protein Isoforms; Protein Structure, Tertiary; RNA - metabolism; Sequence Homology, Amino Acid; Signal Transduction; Space life sciences; Transcription, Genetic; Nasa Discipline Plant Biology; Non-Nasa Center; NASA Discipline Plant Biology; Non-NASA Center
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M111626200

Analysis of the recently completed Arabidopsis genome sequence indicates that ∼31% of the predicted genes could not be assigned to functional categories, as they do not show any sequence similarity with proteins of known function from other organisms. Calmodulin (CaM), a ubiquitous and multifunctional Ca 2+ sensor, interacts with a wide variety of cellular proteins and modulates their activity/function in regulating diverse cellular processes. However, the primary amino acid sequence of the CaM-binding domain in different CaM-binding proteins (CBPs) is not conserved. One way to identify most of the CBPs in the Arabidopsis genome is by protein-protein interaction-based screening of expression libraries with CaM. Here, using a mixture of radiolabeled CaM isoforms from Arabidopsis , we screened several expression libraries prepared from flower meristem, seedlings, or tissues treated with hormones, an elicitor, or a pathogen. Sequence analysis of 77 positive clones that interact with CaM in a Ca 2+ -dependent manner revealed 20 CBPs, including 14 previously unknown CBPs. In addition, by searching the Arabidopsis genome sequence with the newly identified and known plant or animal CBPs, we identified a total of 27 CBPs. Among these, 16 CBPs are represented by families with 2–20 members in each family. Gene expression analysis revealed that CBPs and CBP paralogs are expressed differentially. Our data suggest that Arabidopsis has a large number of CBPs including several plant-specific ones. Although CaM is highly conserved between plants and animals, only a few CBPs are common to both plants and animals. Analysis of Arabidopsis CBPs revealed the presence of a variety of interesting domains. Our analyses identified several hypothetical proteins in the Arabidopsis genome as CaM targets, suggesting their involvement in Ca 2+ -mediated signaling networks.