RRM
2006
Rustbelt RNA Meeting
RRM
|
|
|
|
|
Talk abstracts
Abstract:
Arabidopsis possesses all genes corresponding to the mammalian polyadenylation factors. Of these, the gene encoding Arabidopsis CPSF 30 is complex one, encoding small (app. 28kD) and larger polypeptide (app. ~68 kD). The smaller form corresponds to Arabidopsis ortholog of eukaryotic CPSF30. CPSF30 and its yeast counterpart, Yth1p, are CCCH-type zinc finger proteins that have been shown to possess RNA-binding and nucleolytic activities. Homozygous mutants carrying a T-DNA insertion in the first exon of the Arabidopsis gene encoding CPSF30 are viable (Delaney et al 2006). However, while loss of expression of this gene is not lethal, the mutants show a stunted and auxin-tolerant phenotype. The bulk of poly(A) in the mutant is indistinguishable from that in the wild-type. These observations indicate that the Arabidopsis protein, which is encoded by a single-copy gene, is not absolutely essential for polyadenylation. Further studies have revealed that the purified Arabidopsis protein, like its Drosophila counterpart, possesses a novel endonuclease activity. This protein can cleave RNA in the absence of divalent metal cations indicating the lack of such requirement. However, the nuclease activity is significantly inhibited in the presence of zinc. The nuclease activity is interesting, as it is suggestive of a direct role of this protein in the 3'-end cleavage reaction. However, the inhibitory effects of zinc suggest that the "normal", intact protein may not be an active endonuclease. Current studies are focused on resolving these contrasting properties (RNA-binding vs. endonucleoytic) and better understanding the role of this protein in gene expression in plants.
References:
1. Delaney KJ, Xu R, Zhang J, Li QQ, Yun KY, Falcone DL, Hunt AG. Calmodulin interacts with and regulates the RNA-binding activity of an Arabidopsis polyadenylation factor subunit. Plant Physiol. 2006 Apr; 140(4):1507-21.
Keywords: Polyadenylation, CPSF30, Endonuclease
