| Autor: |
Yoon Duck Koo, Paul Schulze-Lefert, Chang Ho Kang, Byeong Cheol Moon, Min Chul Kim, Woo Sik Chung, Sang Hyoung Lee, Moo Je Cho, Hyun Jin Chun, Sang Yeol Lee, Jae Cheol Jung, Yun Hwan Kang, Chan Young Park, Sun Tae Kim, Jong Kyong Kim, Man Soo Choi, Seong Cheol Koo, Jae Hyuk Yoo |
| Rok vydání: |
2002 |
| Předmět: |
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| Zdroj: |
Journal of Biological Chemistry. 277:19304-19314 |
| ISSN: |
0021-9258 |
| DOI: |
10.1074/jbc.m108478200 |
| Popis: |
Transient influx of Ca2+ constitutes an early event in the signaling cascades that trigger plant defense responses. However, the downstream components of defense-associated Ca2+ signaling are largely unknown. Because Ca2+ signals are mediated by Ca2+-binding proteins, including calmodulin (CaM), identification and characterization of CaM-binding proteins elicited by pathogens should provide insights into the mechanism by which Ca2+ 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 Ca2+-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 Ca2+-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 Ca2+/CaM-dependent enzyme. Expression of OsMlo was strongly induced by a fungal pathogen and by plant defense signaling molecules. We propose that binding of Ca2+-loaded CaM to the C-terminal tail may be a common feature of Mlo proteins. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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