Open AccessThe effect of magnesium and manganese ions on the structure and template activity for reverse transcriptase of polyribocytidylate and its 2'-o-methyl derivative
Author(s) -
Nicholas C. Vamvakopoulos,
John N. Vournakis,
Stuart L. Marcus
Publication year - 1977
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/4.10.3589
Subject(s) - polynucleotide , biology , circular dichroism , enzyme , stacking , manganese , polymerase , thermal stability , ionic strength , primer (cosmetics) , reverse transcriptase , enzyme assay , dna , biochemistry , ionic bonding , dna polymerase , microbiology and biotechnology , ion , chemistry , rna , organic chemistry , gene , aqueous solution
The secondary structure of the hydrogen bonded hybrids polycytidylate-oligodeoxguanylate (poly(rC)-(dG)12-18 and poly (2'-oMe) cytidylate-oligodeoxyguanylate (poly (rCm)-(dG)12-18 was studied at several magnesium and manganese ion concentrations. These hybrids are effective template-primer complexes for the synthesis of poly(dG) by avian myeloblastosis virus (AMV) DNA polymerase under disparate ionic conditions. Circular dichroism spectra and thermal melting data were obtained as a function of ion concentration, including conditions that allow optimum rates of poly (dG) synthesis by each complex. These studies demonstrate that both hybrids can change conformation and stability depending on their ionic environment. Comparison of enzyme activity and physical data suggest that the polymerase recognizes particular secondary structure features. Changes in the activity of the AMV polymerase can be induced by varying the Mg++ and Mn++ concentrations alone and in combination. These variations in enzyme activity are correlated with observed changes in the base-stacking alignment of the synthetic template primers. The ions, therefore, seem to affect enzyme activity by altering the conformation of the polnucleotide complexes.