| 摘要: | 摘要： Deadenylation, also called poly(A) tail shortening, is the first, rate-limiting step in the general cytoplasmic mRNA degradation in eukaryotic cells. The CCR4-NOT complex, containing the two key components carbon catabolite repressor 4 (CCR4) and CCR4-associated factor 1 (CAF1), is a major player in deadenylation. CAF1 belongs to the RNase D group in the DEDD superfamily, and is a protein conserved through evolution from yeast to humans and plants. Every higher plant, including Arabidopsis and rice, contains a CAF1 multigene family. In this study, we identified and cloned four OsCAF1 genes ( OsCAF1A , OsCAF1B , OsCAF1G , and OsCAF1H ) from rice. Four recombinant OsCAF1 proteins, rOsCAF1A, rOsCAF1B, rOsCAF1G, and rOsCAF1H, all exhibited 3′–5′ exonuclease activity in vitro. Point mutations in the catalytic residues of each analyzed recombinant OsCAF1 proteins were shown to disrupt deadenylase activity. OsCAF1A and OsCAF1G mRNA were found to be abundant in the leaves of mature plants. Two types of OsCAF1B mRNA transcript were detected in an inverse expression pattern in various tissues. OsCAF1B was transient, induced by drought, cold, abscisic acid, and wounding treatments. OsCAF1H mRNA was not detected either under normal conditions or during most stress treatments, but only accumulated during heat stress. Four OsCAF1-reporter fusion proteins were localized in both the cytoplasm and nucleus. In addition, when green fluorescent protein fused with OsCAF1B, OsCAF1G, and OsCAF1H, respectively, fluorescent spots were observed in the nucleolus. OsCAF1B fluorescent fusion proteins were located in discrete cytoplasmic foci and fibers. We present evidences that OsCAF1B colocalizes with AtXRN4, a processing body marker, and AtKSS12, a microtubules maker, indicating that OsCAF1B is a component of the plant P-body and associate with microtubules. Our findings provide biochemical evidence that OsCAF1 proteins may be involved in the deadenylation in rice. The unique expression patterns of each OsCAF1 were observed in various tissues when undergoing abiotic stress treatments, implying that each CAF1 gene in rice plays a specific role in the development and stress response of a plant.
其他題名： Plant Mol Biol
出版者： Dordrecht: Springer Science and Business Media LLC
出版日期： 2014-07-01
出處： Plant Molecular Biology, 2014-07, Vol.85 (4), p.443-458
版權： Springer Science+Business Media Dordrecht 2014
識別號： ISSN: 0167-4412
識別號： ISSN: 1573-5028
識別號： EISSN: 1573-5028
識別號： DOI: 10.1007/s11103-014-0196-7
識別號： PMID: 24805883 |
