Open AccessTrf4 and Trf5 Proteins of Saccharomyces cerevisiae Exhibit Poly(A) RNA Polymerase Activity but No DNA Polymerase Activity
Author(s) -
Lajos Haracska,
Robert E. Johnson,
Louise Prakash,
Satya Prakash
Publication year - 2005
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.25.22.10183-10189.2005
Subject(s) - biology , polymerase , dna polymerase , primase , dna clamp , dna polymerase i , dna polymerase ii , biochemistry , microbiology and biotechnology , establishment of sister chromatid cohesion , primer (cosmetics) , dna replication , dna , rna , reverse transcriptase , gene , chemistry , chromatin , cohesin , organic chemistry
TheSaccharomyces cerevisiae Trf4 and Trf5 proteins are members of a distinct family of eukaryotic DNA polymerase β-like nucleotidyltransferases, and a template-dependent DNA polymerase activity has been reported for Trf4. To define the nucleotidyltransferase activities associated with Trf4 and Tr5, we purified these proteins from yeast cells and show that whereas both proteins exhibit a robust poly(A) polymerase activity, neither of them shows any evidence of a DNA polymerase activity. The poly(A) polymerase activity, as determined for Trf4, is strictly Mn2+ dependent and highly ATP specific, incorporating AMP onto the free 3′-hydroxyl end of an RNA primer. Unlike the related poly(A) polymerases from other eukaryotes, which are located in the cytoplasm and regulate the stability and translation efficiency of specific mRNAs, the Trf4 and Trf5 proteins are nuclear, and a multiprotein complex associated with Trf4 has been recently shown to polyadenylate a variety of misfolded or inappropriately expressed RNAs which activate their degradation by the exosome. To account for the effects of Trf4/Trf5 proteins on the various aspects of DNA metabolism, including chromosome condensation, DNA replication, and sister chromatid cohesion, we suggest an additional and essential role for the Trf4 and Trf5 protein complexes in generating functional mRNA poly(A) tails in the nucleus.