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Title: Arabidopsis Cleavage and Polyadenylation Specificity Factor (CPSF)Complex and the Critical Role of 73 kD Subunits in Development

item Dinkins, Randy

Submitted to: Plant Biology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2005
Publication Date: 7/28/2005
Citation: Ruqiang, X., Hongwei, Z., Dinkins, R.D., Xiaowen, C., Li, Q.Q. 2005. Arabidopsis Cleavage and Polyadenylation Specificity Factor (CPSF) Complex and the Critical Role of 73 kD Subunits in Development. Plant Biology Annual Meeting. Seattle, WA. July 16-20, 2005. Abstract 890. 61:799-815.

Interpretive Summary: Plant gene expression is dependent on many factors, including promoter strength, presence or absence of enhancer or repressor elements in the DNA, mRNA translation, as well as 3' mRNA processing and polyadenylation. It is becoming incresingly clear that these components of gene expression are interrelated and some of the proteins required at multiple steps. However, very little is presently known about the mRNA 3'-end processing machinery of higher plants. This work establishes the four major protein components of cleavage an dpolyadenylation specificity factor (CPSF) in plants based on their similarity to these proteins in mammals. In addition, the results demonstrate that one of these proteins, called CPSF73-I,is required at the proper concentration within the cells as both overexpression and underexpression of this protein results in developmental abnormalities and lethality. These results demonstrate for the first time the importance of the 3'mRNA processing in plant growth and development.

Technical Abstract: Cleavage and polyadenylation specificty factor (CPSF) is an important multi-subunit component of the mRNA 3'-end processing apparatus in eukaryotes. We have identified homologues of the mammalian CPSF complex, CPSF160, CPSF100, CPSF73, and atCPSF30, in the Arabidopsis genome. Interestingly, we identified two CPSF73 like proteins, AtCSF73-I and AtCPSF73-II, that share homology with the 73 kD subunit of mammalian CPSF complex. AtCPSF73-I appears to correspond to the functionally characterized mammalian CPSF73 protein while the AtCPSF73-II protein was identified as a novel protein with uncharacterized protein homologues in other multicelluar organisms, but not in yeast. Bothe of the CPSF73 proteins are required a knockout or knockdown mutants are lethal. In addition, expression level of AtCPSF73-I is essential for Arabidopsis development as overexpression of AtCPSF73-I is also lethal. Interestingly, transgenic plants carrying at least an additional copy of the AtCPSF73-I gene, that is, the full length cDNA under the control of its native promoter, appeared normal by was male sterile dure to delayed anther dehiscence. In contrast, we have previously shown that a mutation in the AtCPSF73-II gene was deterimental to the genetic transmission of female gametes. Thus, the two 73kD subunits of CPSF complex appear to have specific functions during flower development. The important roles of nRNA 3'-end processing machinery in modulating plant deveopment are discussed.