|Protein name||Poly(A) polymerase||polynucleotide adenylyltransferaseNTP polymeraseRNA adenylating enzymeAMP polynucleotidylexotransferaseATP-polynucleotide adenylyltransferaseATP:polynucleotidylexotransferasepoly(A) polymerasepoly(A) synthetasepolyadenylate nucleotidyltransferasepolyadenylate polymerasepolyadenylate synthetasepolyadenylic acid polymerasepolyadenylic polymeraseterminal riboadenylate transferasepoly(A) hydrolaseRNA formation factors, PF1adenosine triphosphate:ribonucleic acid adenylyltransferase|
|Synonyms||PAPEC 22.214.171.124Polynucleotide adenylyltransferase|
NM_001179792.3 (DNA/RNA sequence)
|Activity||ATP + RNA(n) = diphosphate + RNA(n+1).|
|Subunit||Component of the cleavage and polyadenylation factor (CPF) complex, which is composed of PTI1, SYC1, SSU72, GLC7, MPE1, REF2, PFS2, PTA1, YSH1/BRR5, SWD2, CFT2/YDH1, YTH1, CFT1/YHH1, FIP1 and PAP1. Interacts with FIR1.|
|References for Catalytic Mechanism|
|References||Sections||No. of steps in catalysis|
|Authors||Martin G, Keller W|
|Title||Mutational analysis of mammalian poly(A) polymerase identifies a region for primer binding and catalytic domain, homologous to the family X polymerases, and to other nucleotidyltransferases.|
|Journal||Biochim Biophys Acta|
|Authors||Wittmann T, Wahle E|
|Title||Purification and characterization of full-length mammalian poly(A) polymerase.|
|Authors||Martin G, Jeno P, Keller W|
|Title||Mapping of ATP binding regions in poly(A) polymerases by photoaffinity labeling and by mutational analysis identifies a domain conserved in many nucleotidyltransferases.|
|Authors||Martin G, Keller W, Doublie S|
|Title||Crystal structure of mammalian poly(A) polymerase in complex with an analog of ATP.|
|Authors||Bard J, Zhelkovsky AM, Helmling S, Earnest TN, Moore CL, Bohm A|
|Title||Structure of yeast poly(A) polymerase alone and in complex with 3'-dATP.|
|This enzyme is homologous to the counterpart enzyme from bovine (M00218 in EzCatDB).|
According to the literature , three acidic residues chelate two Mg2+ ions, which in turn coordinate the alpha-phosphorus of the incoming nucleotide and the 3'-hydroxyl group of the primer. The proton of the attacking hydroxyl group can be abstracted by the nearby acidic residue in the catalytic site. The activated hydroxyl acts as the nucleophile in the subsequent phosphoester bond formation. The reaction results in the inversion of the stereochemistry at the alpha-phosphorus of the now covalently linked nucleoside and ends with the release of Mg2+-pyrophosphate.
The paper  also suggests that the catalytic reaction involves an in-line attack of the 3'-hydroxyl group of the primer on the incoming ATP, without a covalent intermediate.
Considering the structure, Asp102 (PDB;1fa0) acts as a general base, which activate the 3'-hydroxyl group.