Analysis of the functions of recombination-related genes in the generation of large chromosomal deletions by loop-out recombination in Aspergillus oryzae

Eukaryot Cell. 2012 Apr;11(4):507-17. doi: 10.1128/EC.05208-11. Epub 2012 Jan 27.

Abstract

Loop-out-type recombination is a type of intrachromosomal recombination followed by the excision of a chromosomal region. The detailed mechanism underlying this recombination and the genes involved in loop-out recombination remain unknown. In the present study, we investigated the functions of ku70, ligD, rad52, rad54, and rdh54 in the construction of large chromosomal deletions via loop-out recombination and the effect of the position of the targeted chromosomal region on the efficiency of loop-out recombination in Aspergillus oryzae. The efficiency of generation of large chromosomal deletions in the near-telomeric region of chromosome 3, including the aflatoxin gene cluster, was compared with that in the near-centromeric region of chromosome 8, including the tannase gene. In the Δku70 and Δku70-rdh54 strains, only precise loop-out recombination occurred in the near-telomeric region. In contrast, in the ΔligD, Δku70-rad52, and Δku70-rad54 strains, unintended chromosomal deletions by illegitimate loop-out recombination occurred in the near-telomeric region. In addition, large chromosomal deletions via loop-out recombination were efficiently achieved in the near-telomeric region, but barely achieved in the near-centromeric region, in the Δku70 strain. Induction of DNA double-strand breaks by I-SceI endonuclease facilitated large chromosomal deletions in the near-centromeric region. These results indicate that ligD, rad52, and rad54 play a role in the generation of large chromosomal deletions via precise loop-out-type recombination in the near-telomeric region and that loop-out recombination between distant sites is restricted in the near-centromeric region by chromosomal structure.

MeSH terms

  • Aspergillus oryzae / genetics*
  • Aspergillus oryzae / metabolism
  • Carboxylic Ester Hydrolases / genetics
  • Centromere / genetics
  • Centromere / metabolism
  • Chromosome Deletion*
  • Chromosomes, Fungal / genetics*
  • Comparative Genomic Hybridization
  • DNA Breaks, Double-Stranded
  • DNA, Fungal / genetics
  • Endonucleases / metabolism
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Fungal Proteins / physiology
  • Gene Knockout Techniques
  • Recombination, Genetic*
  • Telomere / genetics
  • Telomere / metabolism

Substances

  • DNA, Fungal
  • Fungal Proteins
  • Endonucleases
  • Carboxylic Ester Hydrolases
  • tannase