Is kinase activity essential for biological functions of BRI1?
Brassinosteroids (BRs) are a major group of plant hormones that regulate plant growth and development. BRI1, a protein localized to the plasma membrane, functions as a BR receptor and it has been proposed that its kinase activity has an essential role in BR-regulated plant growth and development. Here we report ... the isolation and molecular characterization of a new allele of bri1, bri1-301, which shows moderate morphological phenotypes and a reduced response to BRs under normal growth conditions. Sequence analysis identified a two-base alteration from GG to AT, resulting in a conversion of 989G to 989I in the BRI1 kinase domain. An in vitro assay of kinase activity showed that bri1-301 has no detectable autophosphorylation activity or phosphorylation activity towards the BRI1 substrates TTL and BAK1. Furthermore, our results suggest that bri1-301, even with extremely impaired kinase activity, still retains partial function in regulating plant growth and development, which raises the question of whether BRI1 kinase activity is essential for BR-mediated growth and development in higher plants.
Mesh Terms:
Alleles, Amino Acid Sequence, Arabidopsis, Arabidopsis Proteins, Base Sequence, Brassinosteroids, Cholestanols, Gene Expression Regulation, Plant, Light, Molecular Sequence Data, Mutant Proteins, Mutation, Phenotype, Protein Kinases, Protein Structure, Tertiary, Seedlings, Steroids, Heterocyclic
Alleles, Amino Acid Sequence, Arabidopsis, Arabidopsis Proteins, Base Sequence, Brassinosteroids, Cholestanols, Gene Expression Regulation, Plant, Light, Molecular Sequence Data, Mutant Proteins, Mutation, Phenotype, Protein Kinases, Protein Structure, Tertiary, Seedlings, Steroids, Heterocyclic
Cell Res.
Date: Apr. 01, 2008
PubMed ID: 18332904
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