Human DNA polymerase η accommodates RNA for strand extension

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Ribonucleotides are natural DNA analogs misinserted by DNA polymerases, forming common genomic lesions.
• Most human DNA polymerases misinsert ribonucleotides, but only a few tolerate RNA strands.

Purpose of the Study:

• To investigate the RNA-accommodating abilities of Y-family DNA polymerases, specifically hpol η.
• To explore the implications of RNA tolerance in DNA replication and repair.

Main Methods:

• Binding affinity assays for DNA/DNA, RNA/DNA, and DNA/RNA duplexes.
• Primer extension assays using hpol η and hpol κ with RNA/DNA substrates.
• Analysis of nucleotide insertion opposite DNA lesions in the presence of RNA.

Main Results:

• hpol η exhibits similar binding affinities for DNA/DNA, RNA/DNA, and DNA/RNA duplexes.
• hpol η and hpol κ accommodate RNA strands during primer extension, inserting deoxyribonucleotides (dNMPs).
• This accommodation occurs even with DNA lesions like 8-oxo-2'-deoxyguanosine or cyclobutane pyrimidine dimer.

Conclusions:

• hpol η possesses an unexpected ability to accommodate RNA strands, expanding the known functions of human DNA polymerases.
• This RNA-accommodating capability suggests new potential roles for hpol η in vivo.
• The findings redefine the traditional understanding of human DNA polymerase capabilities.