Project description:Chloroplast group IIA introns derive from bacterial ribozymes. Their splicing likely requires Maturase K (MatK), which has been largely inaccessible to functional analyses being itself a chloroplast intron-encoded protein. We show that MatK physically interacts with a conserved, essential plastid-localized homolog of starch branching enzymes (BEs), dubbed MATURASE K INTERACTING PROTEIN1 (MKIP1). We demonstrate that MKIP1 proteins have lost BE activity and acquired an insertion enabling direct interaction with the N-terminal region of MatK. Arabidopsis MKIP1 specifically co-precipitates all known intron targets of MatK. Induced MKIP1 silencing results in pale newly emerging leaves, in which the splicing of these intron targets is strongly reduced. Our data suggest that MKIP1 functionally diverged from canonical BEs to facilitate splicing in conjunction with MatK. We propose that the N-terminus of MatK, in turn, has evolved from an RNA-binding domain into a platform for protein interaction, helping its transition towards a general splicing factor.
Project description:Maturase K (MatK) is the only splicing factor encoded in the chloroplast genomes of land plants. Here we used a transplastomic Nicotiana tabacum line, in which the plastidial MatK gene is C-terminally tagged with a 3x-HA tag, to conduct size-exclusion chromatography of soluble protein extracts enriched for chloroplast proteins. Fractions 5 and 6, in which MatK-HA was found most abundant by western blot analysis, were subjected to mass spectrometry analysis.
Project description:Campeiostachys nutans, a dominant perennial grass in the Qinghai-Tibet Plateau, exhibits high tolerance to salt stress. The Salt Overly Sensitive (SOS) pathway is key to plant salt stress tolerance. However, the pivotal role of the SOS pathway in response to salt stress in C. nutans remains unknown. Here, we identified CnbHLH130 as a novel transcriptional activator of CnCBL10, directly binds to the G-box motif in the promoter. CnbHLH130 responds to salt stress and positively regulate salt tolerance in rice and C. nutans. Interestingly, we found CnCBL10 and CnCIPK4 interact with CnbHLH130 by a Y2H screening assay. The interactions were confirmed by split-luciferase complementation (split-LUC), Pull-down, Co-immunoprecipitation (Co-IP) and bimolecular fluorescence complementation (BiFC) assays. Moreover, CnbHLH130 enhanced the interaction between CnCBL10 and CnCIPK4, which further phosphorylate and activate Na+/H+ antiporter CnSOS1 to exclude excess cytosolic Na+ from cells in the shoots. Genetic evidence showed that CnCBL10, CnCIPK4 and CnbHLH130 coordinately regulates salt tolerance in plants. In summary, this study demonstrated that CnbHLH130 acts as a novel core component and transcriptional activator regulating CnCBL10-CnCIPK4 mediated SOS pathway, thus conferring to the salt tolerance in C. nutans. This work advanced our understandings of how an alpine plant greatly survived in the Qinghai-Tibet Plateau by concise regulation of the SOS pathway in response to salt stress.
Project description:To investigate the effects of C. nutans DCM fraction on HeLa cells using transcriptomic analysis. We then performed gene expression profiling analysis using data obtained from RNA-seq of two different condition at two replicates.