Year of Publication

2009

Degree Name

Master of Science (MS)

Document Type

Thesis

College

Agriculture

Department

Crop Science

First Advisor

Dr. Arthur G. Hunt

Abstract

3’-end modification by polyadenylation is a ubiquitous feature of almost all eukaryotic mRNA species and is catalyzed by a consortium of enzymes, the polyadenylation factors. Poly(A) polymerase (PAP), the enzyme catalyzing the addition of adenosine residues during the polyadenylation stage, exists in four isoforms within Arabidopsis. In silico and yeast two-hybrid studies showed that PAP1 has unique expression and interaction pattern in Arabidopsis, suggesting non-canonical functions of PAP1. Its exclusive interaction with PAP4 has not been reported in other living systems until now and hints at a difference in polyadenylation in plants with respect to mammals and yeast. Cleavage Stimulation Factor (CstF), a heterotrimeric complex of the polyadenylation factors CstF50, CstF64 and CstF77, plays a role largely in cleavage of pre-mRNA. This study highlights some aspects of the Arabidopsis homologs of CstF64 and CstF77, central to various cellular processes other than nuclear polyadenylation. In silico studies showed an elevated expression of CstF64 in the pollen while that of CstF77 remained fairly low. Yeast two-hybrid assays indicated a novel kind of interaction of CstF64 with Fip1(V). It is also speculated from sub-cellular localization techniques by agroinfiltration in tobacco leaves that CstF64 localizes in the cytoplasm and CstF77 in the nucleus, as found for the orthologs of CstF77 in other systems.

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