Single-nucleotide mutation rate increases close to insertions/deletions in eukaryotes.

Area of Science:

• Genetics
• Genomics
• Evolutionary Biology

Background:

• Mutation hotspots are observed in genomes, but their formation mechanisms are not fully understood.
• Insertions/deletions (indels) are common genomic variations.
• Understanding mutation patterns is crucial for studying evolution and disease.

Purpose of the Study:

• To investigate the relationship between indels and nucleotide substitutions.
• To determine if indels influence mutation rates in surrounding DNA.
• To identify general mechanisms for mutation hotspot formation.

Main Methods:

• Analyzed nucleotide divergence around indels in six diverse species (primates, rodents, fruit fly, rice, yeast).
• Correlated nucleotide divergence with indel size and abundance.
• Examined nucleotide substitution patterns in lineages with and without indels.
• Used yeast polymorphism data to estimate mutation rate increases.

Main Results:

• Nucleotide divergence is significantly elevated around indels, decreasing with distance.
• Divergence is correlated with indel size and frequency.
• Mutations are more frequent in lineages with indels compared to those without.
• Heterozygosity for indels appears to be mutagenic to flanking DNA.

Conclusions:

• Indels act as mutagens, increasing substitution rates in adjacent genomic regions.
• This indel-associated substitution is a general mutational mechanism across species.
• The findings provide insights into the formation of mutation hotspots and genome evolution.