GC high

Edge evidence

• AT-biased mutation pressure produces GC high METPO:2000202

  AT-biased mutation pressure produces low genome-wide GC composition.

  • DOI:10.1186/1471-2148-10-374 mutation bias Supports mutation bias as the primary driver of low-GC composition.
• GC high is a GC content rdfs:subClassOf

  GC high is a quantitative bin of the GC-content phenotype.

  • DOI:10.1038/nrg2358 GC content Supports the ≤42.65% bin as a value within the GC-content distribution.
• Cytosine deamination contributes to GC high RO:0002326

  Cytosine deamination drives AT-enriching G->A transitions lowering genome-wide GC.

  • DOI:10.1038/s41467-026-71228-y Spontaneous cytosine deamination produces unrepaired uracil read as thymine, causing G->A transitions (pages 6-7).
• Loss of uracil-DNA glycosylase (UDG family) causally promotes GC high

  Loss of UDG repair leaves deaminated cytosine unrepaired, promoting GC erosion.

  • DOI:10.1038/s41467-026-71228-y Absence of DNA glycosylases compromises repair of deaminated cytosine (uracil), causing G->A transitions (pages 6-7).
• Loss of BER glycosylases (Tag/AlkA/MPG/Nei) causally promotes GC high

  Concerted loss of BER glycosylases biases mutation spectra toward GC-eroding changes.

  • DOI:10.1038/s41467-026-71228-y Concerted loss of Tag/AlkA/MPG, UDG, Nei, MutT removed defenses against small-base lesions; mutation spectra biased toward GC-eroding changes (pages 8-9).
• Loss of MutT nucleotide-pool sanitization causally promotes GC high

  Loss of MutT nucleotide-pool sanitization contributes to GC-eroding mutational dysregulation.

  • DOI:10.1038/s41467-026-71228-y Concerted loss of sanitizing enzymes including MutT removed defenses; analogues showed mutation spectra biased toward GC-eroding changes (pages 8-9).
• Hypermutator phenotype causally promotes GC high

  Hypermutator state provides a mechanistic path to genome-wide AT enrichment.

  • DOI:10.1038/s41467-026-71228-y Mutator phenotypes (10- to 1e4-fold) with GC-eroding mutation spectra provide a mechanistic path to AT-enrichment (pages 8-9).
• Third-codon-position AT enrichment contributes to GC high RO:0002326

  AT-rich substitution at third codon positions is a principal driver of decreased GC.

  • DOI:10.1038/s41467-026-71228-y Substitution of third codon positions with AT-rich nucleotides identified as a principal driver of decreased GC (pages 9-10).
• Purifying selection and biased gene conversion opposes GC high

  Purifying selection and biased gene conversion counteract AT bias, resisting GC decline.

  • DOI:10.63635/mrj.v1i4.188 Purifying selection and biased gene conversion can counteract AT bias (pages 3-5).