Mlo, a modulator of plant defense and cell death, is a novel calmodulin-binding protein. Isolation and characterization of a rice Mlo homologue
| Autor: | Min Chul, Kim, Sang Hyoung, Lee, Jong Kyong, Kim, Hyun Jin, Chun, Man Soo, Choi, Woo Sik, Chung, Byeong Cheol, Moon, Chang Ho, Kang, Chan Young, Park, Jae Hyuk, Yoo, Yun Hwan, Kang, Seong Cheol, Koo, Yoon Duck, Koo, Jae Cheol, Jung, Sun Tae, Kim, Paul, Schulze-Lefert, Sang Yeol, Lee, Moo Je, Cho |
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| Rok vydání: | 2002 |
| Předmět: |
Cytoplasm
DNA Complementary Time Factors Molecular Sequence Data Genes Plant Binding Competitive Calmodulin Escherichia coli Protein Isoforms Amino Acid Sequence Cloning Molecular Phylogeny Gene Library Plant Proteins Base Sequence Sequence Homology Amino Acid Phosphoric Diester Hydrolases Cell Membrane Oryza Blotting Northern Recombinant Proteins Protein Structure Tertiary Blotting Southern Mutagenesis Site-Directed Calcium Peptides Protein Binding Signal Transduction Subcellular Fractions |
| Zdroj: | The Journal of biological chemistry. 277(22) |
| ISSN: | 0021-9258 |
| Popis: | Transient influx of Ca(2+) constitutes an early event in the signaling cascades that trigger plant defense responses. However, the downstream components of defense-associated Ca(2+) signaling are largely unknown. Because Ca(2+) signals are mediated by Ca(2+)-binding proteins, including calmodulin (CaM), identification and characterization of CaM-binding proteins elicited by pathogens should provide insights into the mechanism by which Ca(2+) regulates defense responses. In this study, we isolated a gene encoding rice Mlo (Oryza sativa Mlo; OsMlo) using a protein-protein interaction-based screening of a cDNA expression library constructed from pathogen-elicited rice suspension cells. OsMlo has a molecular mass of 62 kDa and shares 65% sequence identity and scaffold topology with barley Mlo, a heptahelical transmembrane protein known to function as a negative regulator of broad spectrum disease resistance and leaf cell death. By using gel overlay assays, we showed that OsMlo produced in Escherichia coli binds to soybean CaM isoform-1 (SCaM-1) in a Ca(2+)-dependent manner. We located a 20-amino acid CaM-binding domain (CaMBD) in the OsMlo C-terminal cytoplasmic tail that is necessary and sufficient for Ca(2+)-dependent CaM complex formation. Specific binding of the conserved CaMBD to CaM was corroborated by site-directed mutagenesis, a gel mobility shift assay, and a competition assay with a Ca(2+)/CaM-dependent enzyme. Expression of OsMlo was strongly induced by a fungal pathogen and by plant defense signaling molecules. We propose that binding of Ca(2+)-loaded CaM to the C-terminal tail may be a common feature of Mlo proteins. |
| Databáze: | OpenAIRE |
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