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Investigation into the interaction between Arabidopsis thaliana calmodulinlike proteins 13 and 14 and calmodulin-binding transcriptional activators
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Authors
Hau, Bryan
Date
Type
thesis
Language
eng
Keyword
CAMTA , Salinity Response , Arabidopsis , Calcium Signaling , Calmodulin , Calmodulin-like protein , Osmotic Response
Alternative Title
Abstract
A common theme among eukaryotic cells is the use of calcium ions (Ca2+) as second messengers to coordinate responses during information processing. In plants, Ca2+ signals are evoked during responses to abiotic and biotic stresses and during development. These signals are detected by Ca2+-binding proteins (sensors), such as the evolutionarily-conserved protein calmodulin (CaM), which regulates various downstream target proteins to organize signal transduction pathways. In addition to CaM, plants possess many CaM-like proteins (CMLs) that are not found in animals. The genetic model, Arabidopsis, has seven CaMs and 50 CMLs, most of which remain unstudied. Previous work in our lab found that the Arabidopsis thaliana paralogs, CML13 and CML14, possess unique biochemical properties among CaMs and CMLs and interact with protein targets that have multiple isoleucine/glutamine (IQ) domains. Here, I explored the interaction of CaM, CML13, and CML14 with the six members of the CaM-binding transcriptional activator (CAMTA) family, all of which are predicted to possess at least two IQ regions. Using a combination of in planta and in vitro protein-interaction assays, I observed the IQ-region of all six CAMTAs associated with CaM, CML13, and CML14 relative to negative controls. Full-length CAMTAs, except CAMTA4, which was not available for testing, associated in planta with CaM, CML13, and CML14. Delineation of individual IQ regions from CAMTA6 and CAMTA3 suggested some preference for specific CAMTA-IQ regions among CaM, CML13, and CML14. In vitro binding assays indicated that the C-terminal region of CAMTA6 may influence the specificity and/or calciumdependence of CaM, CML13, and CML14 binding to IQ regions. Genetic analyses, using camta6 mutant plants, transgenic plants overexpressing GFP-CML13 or GFP-CML14, or plants lacking full-length CML13, showed differential responses to salinity stress, when compared to wild-type plants. Plants lacking CAMTA6 or CML13 showed enhanced salinity tolerance whereas overexpression of CML13 or CML14 led to increased sensitivity. Collectively, my data indicate that CML13 and CML14 participate in abiotic stress signaling and support the hypothesis that in addition to CaM, CML13 and CML14 are CAMTA effectors which may contribute to the regulation of gene expression during stress response.
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Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.