Poster: Reproductive Development
Abs #
474: Identification and characterization of PiRING1, a RING finger protein which interacts with the kinase domain of PRK1
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Presenter: |
Skirpan, Andrea L, als152@psu.edu |
Authors | Skirpan, Andrea L (A) Kao, Teh-hui (A) | | Affiliations: |
(A): The Pennsylvania State University, Biochemistry and Molecular Biology
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Many receptor-like kinases have been identified in plants and have been shown by genetic or transgenic knockouts to play diverse physiological roles. We have previously identified one such protein, PRK1, a predominantly pollen expressed receptor-like kinase in Petunia inflata and have shown by antisense RNA that it is required for microspores to progress from the unicellular to bicellular stage of pollen development. To better understand the signaling processes regulated by PRK1, it is important to identify components of the signaling pathway. Using the kinase domain of PRK1 as bait in a yeast two-hybrid screen of a pollen cDNA library, we identified 4 classes of potentially interacting proteins. Several positive cDNA clones encode a protein we named PiRING1 because the regions encoded by all of them contain a C3HC4 subtype of the RING finger domain. RING finger domain containing proteins have been shown to function in protein-protein interactions and more specifically as E3 ubiquitin ligases. E3 interacts with E2 ubiquitin-conjugating enzyme, and these two enzymes along with E1 ubiquitin-activating enzyme catalyze the transfer of multiple ubiquitin units to specific protein substrates recognized by E3, which are subsequently degraded by the 26S proteasome. PiRING1 is expressed solely in mature pollen and possibly pollen tubes and its interaction with PRK1 was confirmed by in vitro binding assays. Our identification of PiRING1 raises an interesting possibility that it is a E3 ubiquitin ligase and that it targets PRK1 for degradation to negatively regulate the PRK1 signaling pathway. The action of PiRING1 on PRK1 is being investigated via dominant negative, overexpression and antisense approaches.
