Direct recognition of homology between double helices of DNA in Neurospora crassa

Nat Commun. 2014 Apr 3;5:3509. doi: 10.1038/ncomms4509.

Abstract

Chromosomal regions of identical or nearly identical DNA sequence can preferentially associate with one another in the apparent absence of DNA breakage. Molecular mechanism(s) underlying such homology-dependent pairing phenomena remain(s) unknown. Using Neurospora crassa repeat-induced point mutation (RIP) as a model system, we show that a pair of DNA segments can be recognized as homologous, if they share triplets of base pairs arrayed with the matching periodicity of 11 or 12 base pairs. This pattern suggests direct interactions between slightly underwound co-aligned DNA duplexes engaging once per turn and over many consecutive turns. The process occurs in the absence of MEI3, the only RAD51/DMC1 protein in N. crassa, demonstrating independence from the canonical homology recognition pathway. A new perspective is thus provided for further analysis of the breakage-independent recognition of homology that underlies RIP and, potentially, other processes where sequence-specific pairing of intact chromosomes is involved.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • DNA, Fungal / chemistry*
  • DNA, Fungal / genetics*
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Neurospora crassa / chemistry
  • Neurospora crassa / genetics*
  • Neurospora crassa / metabolism
  • Nucleic Acid Conformation
  • Point Mutation
  • Repetitive Sequences, Nucleic Acid
  • Sequence Homology, Nucleic Acid

Substances

  • DNA, Fungal
  • Fungal Proteins