Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pollen tube growth is influenced by interaction between pollen proteins and the pistil extracellular matrix. The transmitting tract-specific glycoprotein (NaTTS) and 120-kDa glycoprotein (120K) are two pistil arabinogalactan proteins (AGPs) that share a conserved C-terminal domain (CTD) and directly influence pollen tubes in Nicotiana alata. 120K and other extracellular matrix proteins are taken up and transported to vacuoles of growing pollen tubes. We hypothesize that signaling and trafficking processes inside pollen tubes are important for controlling pollen tube growth. We performed a yeast two-hybrid screen of pollen cDNAs using sequences from 120K and NaTTS as baits. We found that an S-RNase-binding protein (SBP1), a C2 domain-containing protein (NaPCCP), and a putative cysteine protease bound to the AGP baits. SBP1 from Petunia hybrida and Solanum chacoense is a putative E3 ubiquitin ligase that binds to S-RNase and other proteins. C2 domain-containing proteins bind lipids and can regulate myriad cellular processes. Cysteine proteases are often associated with the degradation of vacuolar proteins. Expression analysis revealed that transcripts for these proteins are expressed in mature pollen. NaPCCP and NaSBP1 were characterized further because of their potential roles in signaling and trafficking. In vitro pull-down assays verified binding between maltose-binding protein (MBP) fusions, MBP::NaPCCP or MBP::NaSBP1 and glutathione S-transferase (GST), GST::AGP CTD fusions. NaSBP1 binds to the AGP CTDs through its helical and RING domains. NaPCCP binds through its C-terminal region. Binding between NaPCCP and NaSBP1 and the pistil AGPs may contribute to signaling and trafficking inside pollen tubes growing in planta.
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PMID:Pollen proteins bind to the C-terminal domain of Nicotiana alata pistil arabinogalactan proteins. 1867 68

Many flowering plants adopt self-incompatibility (SI) to maintain their genetic diversity. In species of Solanaceae, Plantaginaceae, and Rosaceae, SI is genetically controlled by a single S-locus with multiple haplotypes. The S-locus has been shown to encode S-RNases expressed in pistil and multiple SLF (S-locus F-box) proteins in pollen controlling the female and male specificity of SI, respectively. S-RNases appear to function as a cytotoxin to reject self-pollen. In addition, SLFs have been shown to form SCF (SKP1/Cullin1/F-box) complexes to serve as putative E3 ubiquitin ligase to interact with S-RNases. Previously, two different mechanisms, the S-RNase degradation and the S-RNase compartmentalization, have been proposed as the restriction mechanisms of S-RNase cytotoxicity allowing compatible pollination. In this study, we have provided several lines of evidence in support of the S-RNase degradation mechanism by a combination of cellular, biochemical and molecular biology approaches. First, both immunogold labeling and subcellular fractionation assays showed that two key pollen SI factors, PhS3L-SLF1 and PhSSK1 (SLF-interacting SKP1-like1) from Petunia hybrida, a Solanaceous species, are co-localized in cytosols of both pollen grains and tubes. Second, PhS3L-RNases are mainly detected in the cytosols of both self and non-self-pollen tubes after pollination. Third, we found that PhS-RNases selectively interact with PhSLFs by yeast two-hybrid and co-immunoprecipitation assays. Fourth, S-RNases are specifically degraded in compatible pollen tubes by non-self SLF action. Taken together, our results demonstrate that SCF(SLF-mediated) non-self S-RNase degradation occurs in the cytosol of pollen tube through the ubiquitin/26S proteasome system serving as the major mechanism to neutralize S-RNase cytotoxicity during compatible pollination in P. hybrida.
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PMID:SCF(SLF)-mediated cytosolic degradation of S-RNase is required for cross-pollen compatibility in S-RNase-based self-incompatibility in Petunia hybrida. 2510 Nov 13