Answer to Question #122394 in Molecular Biology for Sania Zahoor

Question

Q#1: Why two metal ions (Mg2+) participate in DNA polymerase reaction and why not in DNA polymerase?

Q#2: What is the distance between nucleotide -10 and -35 sequence and for which activity it is important?

Answer 1

1. Two magnesium ions facilitate the reaction by interacting with phosphate groups of nucleotides. Magnesium ions stabilise OH-groups and ionised oxygens contributing to the reaction. As a result, magnesium ions are required for stabilization of nucleotides but not polymerase.

2. The distance between nucleotides -10 and -35 equals 25 nucleotides. These sequences are required for the binding of RNA polymerase (sigma-subunit) to prokaryotic promoter region.