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The enzyme that adds poly(A) to mRNAs is a classical poly(A) polymerase
V J Bardwell1, D Zarkower, M Edmonds
1Cell and Molecular Biology Program, University of Wisconsin, Madison 53706-1569.
Molecular and Cellular Biology
|February 1, 1990
Summary
The enzyme poly(A) polymerase adds the poly(A) tail to messenger RNAs (mRNAs) in eukaryotes. This process requires specificity factors for accurate mRNA substrate recognition, a conserved mechanism.
Area of Science:
- Molecular Biology
- Biochemistry
- Eukaryotic Gene Expression
Background:
- Nearly all eukaryotic messenger RNAs (mRNAs) possess a poly(A) tail, crucial for stability and translation.
- Polyadenylation, the addition of this tail, occurs post-transcriptionally but the responsible enzyme's precise role and specificity mechanisms were historically unclear.
Purpose of the Study:
- To identify and characterize the enzyme responsible for mRNA polyadenylation.
- To elucidate the mechanism by which polyadenylation achieves substrate specificity.
Main Methods:
- Enzyme activity assays using poly(A) polymerase from calf thymus.
- Investigation of substrate specificity in conjunction with specificity factors from cultured human cells.
Main Results:
- The enzyme poly(A) polymerase, previously identified but functionally uncharacterized, was confirmed as the catalyst for poly(A) tail addition.
- Poly(A) polymerase exhibits no intrinsic mRNA substrate specificity.
- Specificity is conferred through interactions with distinct specificity factors, enabling precise polyadenylation of appropriate mRNA substrates.
Conclusions:
- Poly(A) polymerase is the key enzyme responsible for mRNA polyadenylation in eukaryotes.
- The interaction between poly(A) polymerase and specificity factors is essential for accurate polyadenylation and is a conserved biological mechanism.