Biochemical Characterization of R-Loop Degradation by Chloroplast-Localized RNase H1 from <i>Arabidopsis thaliana</i>.

ABSTRACT: R-loops are three-stranded nucleic acid structures implicated in genome regulation and stability. In Arabidopsis thaliana, the chloroplast-localized RNase H1 enzyme (AtRNH1C) is important for chloroplast development and genome integrity; however, its molecular activity has not been experimentally verified. In the present study, we characterized the enzymatic activity of recombinant AtRNH1C toward model R-loops of various structures. Using a set of synthetic R-loop substrates, we demonstrate that AtRNH1C cleaves the RNA within DNA/RNA hybrids with a strong preference for purine-rich sequences, most notably at G↓X dinucleotides. Kinetic assays showed that the enzyme's efficiency is highly dependent on the length of the hybrid duplex but is not affected by a G-quadruplex structure in t

SUBMITTER: Gavrilova AA 

PROVIDER: S-EPMC12652420 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature