Poly (A) polymerase of bovine lymphosarcoma

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Polyadenylation is a crucial post-transcriptional modification in eukaryotes.
• Poly(A) polymerase (PAP) is the key enzyme responsible for adding the poly(A) tail.
• Understanding PAP's properties is essential for comprehending gene regulation.

Purpose of the Study:

• To extensively purify and characterize poly(A) polymerase from bovine lymphosarcoma.
• To compare the properties of lymphosarcoma PAP with those from other sources, such as calf thymus.

Main Methods:

• Purification of poly(A) polymerase from low-salt extracts of bovine lymphosarcoma.
• Enzymatic assays to determine substrate specificity, cofactor requirements, and primer preferences.

Main Results:

• The purified enzyme is dependent on manganese ions (Mn2+) and requires an oligonucleotide or RNA primer.
• It specifically incorporates adenosine triphosphate and is inhibited by other nucleotides.
• Oligoadenylate and ribosomal RNA serve as effective primers, while transfer RNA and poly(A) are poor primers.
• RNA transcribed in vitro by homologous RNA polymerase is an efficient primer.
• The enzyme's properties are highly similar to Mn2+-activated PAP from calf thymus.
• Similar quantities of the enzyme are found in both lymphosarcoma and calf thymus.

Conclusions:

• Bovine lymphosarcoma contains a Mn2+-dependent poly(A) polymerase with characteristics similar to that found in calf thymus.
• The enzyme's primer preference suggests specific roles in RNA metabolism.
• The comparable enzyme levels indicate a conserved biological role across different bovine tissues.