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Search The CSA
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Catalytic Site Atlas

CSA LITERATURE entry for 1fa0

E.C. namepolynucleotide adenylyltransferase
SpeciesSaccharomyces cerevisiae (Baker's yeast)
E.C. Number (IntEnz) 2.7.7.19
CSA Homologues of 1fa0There are 18 Homologs
CSA Entries With UniProtID P29468
CSA Entries With EC Number 2.7.7.19
PDBe Entry 1fa0
PDBSum Entry 1fa0
MACiE Entry 1fa0

Literature Report

IntroductionPoly(A) polymerase (PAP) catalyses the addition of a poly-adenosine tail to almost all eukaryotic mRNAs. This poly(A) tail has numerous functions in eukaryotes: it facilitates transport of the mRNA from the nucleus, regulates mRNA stability, and increases the efficiency of translation. Poly(A) tails are added to mRNA by a multiprotein complex that recognises the polyadenylation signal, cleaves the precursor mRNA, and adds the additional nucleotides. The poly(A) polymerase component retains its polymerase activity when isolated from the holoenzyme assembly and will processively add long stretches of adenosine nucleotides to an RNA primer in vitro.
MechansimPoly(A) polymerase is thought to use the two-metal-ion mechanism proposed for all nucleic acid polymerases. One metal ion, dubbed Metal A (MN 601 in structure 1fa0) contacts the 3' OH of the primer and lowers its pKa, activating it for in-line nucleophilic attack on the alpha phosphate of the incoming ATP. Accumulation of negative charge on the alpha phosphate in the pentacoordinate transition state is stabilised by both Metal A and Metal B (MN 600 in structure 1fa0). Metal B additionally functions to stabilise accumulation of negative charge on the pyrophosphate leaving group. Lys 215 may also stabilise negative charge on the pyrophosphate leaving group.
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Catalytic Sites for 1fa0

Annotated By Reference To The Literature - Site 1 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LysA215215macie:sideChainProposed to stabilise the negatively charged pyrophosphate leaving group.

Annotated By Reference To The Literature - Site 2 (Perform Site Search)
ResidueChainNumberUniProtKB NumberFunctional PartFunctionTargetDescription
LysB215215macie:sideChainProposed to stabilise the negatively charged pyrophosphate leaving group.

Literature References

Notes:
Bard J
Structure of yeast poly(A) polymerase alone and in complex with 3'-dATP.
Science 2000 289 1346-1349
PubMed: 10958780
Brautigam CA
Structural and functional insights provided by crystal structures of DNA polymerases and their substrate complexes.
Curr Opin Struct Biol 1998 8 54-63
PubMed: 9519297
DoubliƩ S
The mechanism of action of T7 DNA polymerase.
Curr Opin Struct Biol 1998 8 704-712
PubMed: 9914251
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