title: Identification of a S-ribonuclease-binding protein in Petunia hybrida.
abstract: To investigate protein-protein interactions in gametophytic self-incompatibility, we used a yeast two-hybrid assay to identify proteins that could interact with the S-ribonuclease protein. These assays identified a pollen-expressed protein, which we have named PhSBP1, that appears to bind with a high degree of specificity to the Petunia hybrida S-ribonuclease. Although PhSBP1 activates reporter gene expression only when expressed in tandem with a S-RNAse bait protein, binding is not allele-specific. Sequence analysis demonstrated that PhSBP1 contained a C-terminal cysteine-rich region that includes a RING-HC domain. Because many RING-finger domain proteins appear to function as E3 ubiquitin ligases, our results suggest that ubiquitination and protein degradation may play a role in regulating self-incompatibility interactions. Together, these results suggest that PhSBPI may be a candidate for the recently proposed general inhibitor (RI) of self-incompatibility ribonucleases.
authors.affiliation: Department of Biological Sciences and Plant Molecular Biology Center, Northern Illinois University, DeKalb, 60115-2861, USA. tsmis@niu.edu
authors.forename: T L
authors.initials: TL
authors.lastname: Sims
authors.forename: M
authors.initials: M
authors.lastname: Ordanic
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012260:Ribonucleases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D019657:Solanaceae / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics; D020798:Two-Hybrid System Techniques
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D047908:Intracellular Signaling Peptides and Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C445076:S-ribonuclease-binding protein, Petunia hybrida; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D012260:Ribonucleases; C022542:ribonuclease S