Li, Yongqing , Topp, Stephanie , Hua, Jian .
Study of biochemical activities of BON1, BAP1, and BAP2 in regulating plant growth and defense response.
The Arabidopsis BON1 and its functional partners BAP1 and BAP2 are negative regulators of cell death and defense response. BON1 is a member of a conserved copine family with two C2 domains and a VWA domain while BAP1 and BAP2 are small proteins with one C2 domain. The goal of this study is to use site-directed mutagenesis to study the biochemical activities these proteins use for their biological functions. The C2 domains of BON1 and BAP1 have been shown to bind to phospholipids in Ca2+-dependent manner and the amino-terminus of BON1 is predicted to contain a myristoylation site Gly2. They are likely responsible for the membrane localization of these proteins. To study the role of lipid binding activity in BON1/BAP function, D to A mutations were generated on the conserved aspartates essential for calcium binding in the C2 domains of BON1 and BAPs. G2A mutation was also made in BON1. To test a potential kinase activity of the VWA domain of BON1, A350 and G353 in the conserved glycine loop for ATP binding and the essential K391 for kinase activity are mutated into V, V, and A, respectively. Highly conserved sites between BAP1 and BAP2 were also mutated in BAP1. All the mutated and wild type BON1, BAP1 and BAP2 genes have been transformed into bon1, bap1and bap1/+,bap2 mutants respectively to determine if they can rescue their mutant phenotypes. Ongoing analysis showed that mutations in some Asp sites in the C2 domains of BON1 and BAP2, and mutations in the conserved regions in BAP1 abolished their function, indicating that the calcium-dependent lipid binding is essential for BON1/BAP function. This structure function analysis when completed will enhance our understanding of the activities of these proteins and their roles in cell death and defense regulation.
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1 - Cornell University, Plant Biology
2 - Cornell University, Molecular Biology and Genetics, 144 Emerson Hall, Ithaca, NY, 14850, USA
BON1,BAP1 & 2.
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM