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A Ca2+/calmodulin-dependent protein kinase required for symbiotic nodule development: Gene identification by transcript-based cloning.

ABSTRACT: In the establishment of the legume-rhizobial symbiosis, bacterial lipochitooligosaccharide signaling molecules termed Nod factors activate the formation of a novel root organ, the nodule. Nod factors elicit several responses in plant root hair cells, including oscillations in cytoplasmic calcium levels (termed calcium spiking) and alterations in root hair growth. A number of plant mutants with defects in the Nod factor signaling pathway have been identified. One such Medicago truncatula mutant, dmi3, exhibits calcium spiking and root hair swelling in response to Nod factor, but fails to initiate symbiotic gene expression or cell divisions for nodule formation. On the basis of these data, it is thought that the dmi3 mutant perceives Nod factor but fails to transduce the signal downstream of calcium spiking. Additionally, the dmi3 mutant is defective in the symbiosis with mycorrhizal fungi, indicating the importance of the encoded protein in multiple symbioses. We report the identification of the DMI3 gene, using a gene cloning method based on transcript abundance. We show that transcript-based cloning is a valid approach for cloning genes in barley, indicating the value of this technology in crop plants. DMI3 encodes a calcium/calmodulin-dependent protein kinase. Mutants in pea sym9 have phenotypes similar to dmi3 and have alterations in this gene. The DMI3 class of proteins is well conserved among plants that interact with mycorrhizal fungi, but it is less conserved in Arabidopsis thaliana, which does not participate in the mycorrhizal symbiosis.

SUBMITTER: Mitra RM

PROVIDER: S-EPMC384810 | biostudies-literature | 2004 Mar

REPOSITORIES: biostudies-literature

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A Ca2+/calmodulin-dependent protein kinase required for symbiotic nodule development: Gene identification by transcript-based cloning.

Mitra Raka M RM Gleason Cynthia A CA Edwards Anne A Hadfield James J Downie J Allan JA Oldroyd Giles E D GE Long Sharon R SR

Proceedings of the National Academy of Sciences of the United States of America 20040301 13

In the establishment of the legume-rhizobial symbiosis, bacterial lipochitooligosaccharide signaling molecules termed Nod factors activate the formation of a novel root organ, the nodule. Nod factors elicit several responses in plant root hair cells, including oscillations in cytoplasmic calcium levels (termed calcium spiking) and alterations in root hair growth. A number of plant mutants with defects in the Nod factor signaling pathway have been identified. One such Medicago truncatula mutant, ...[more]

PMID: 15070781

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Project description:During the acquisition of memories, influx of Ca2+ into the postsynaptic spine through the pores of activated N-methyl-D-aspartate-type glutamate receptors triggers processes that change the strength of excitatory synapses. The pattern of Ca2+influx during the first few seconds of activity is interpreted within the Ca2+-dependent signaling network such that synaptic strength is eventually either potentiated or depressed. Many of the critical signaling enzymes that control synaptic plasticity,including Ca2+/calmodulin-dependent protein kinase II (CaMKII), are regulated by calmodulin, a small protein that can bindup to 4 Ca2+ ions. As a first step toward clarifying how the Ca2+-signaling network decides between potentiation or depression, we have created a kinetic model of the interactions of Ca2+, calmodulin, and CaMKII that represents our best understanding of the dynamics of these interactions under conditions that resemble those in a postsynaptic spine. We constrained parameters of the model from data in the literature, or from our own measurements, and then predicted time courses of activation and autophosphorylation of CaMKII under a variety of conditions. Simulations showed that species of calmodulin with fewer than four bound Ca2+ play a significant role in activation of CaMKII in the physiological regime,supporting the notion that processing of Ca2+ signals in a spine involves competition among target enzymes for binding to unsaturated species of CaM in an environment in which the concentration of Ca2+ is fluctuating rapidly. Indeed, we showed that dependence of activation on the frequency of Ca2+ transients arises from the kinetics of interaction of fluctuating Ca2+with calmodulin/CaMKII complexes. We used parameter sensitivity analysis to identify which parameters will be most beneficial to measure more carefully to improve the accuracy of predictions. This model provides a quantitative base from which to build more complex dynamic models of postsynaptic signal transduction during learning.

Dataset Information

A Ca2+/calmodulin-dependent protein kinase required for symbiotic nodule development: Gene identification by transcript-based cloning.

Publications

A Ca2+/calmodulin-dependent protein kinase required for symbiotic nodule development: Gene identification by transcript-based cloning.

Similar Datasets

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