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Microhomology directs diverse DNA break repair pathways and chromosomal translocations

Diana D Villarreal1, Kihoon Lee, Angela Deem

  • 1Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America.

Plos Genetics
|November 13, 2012
PubMed

Insights

This study reveals how microhomology-mediated repair (MHMR) causes chromosomal rearrangements. Longer microhomology sequences (>15 bp) require Pol32, while shorter ones (<14 bp) are distinct and less efficient.

Area of Science:

  • Genetics
  • Molecular Biology
  • Genomics

Background:

  • Chromosomal structural changes are linked to cancer and genetic disorders.
  • The mechanisms behind microhomology-mediated repair (MHMR) at rearrangement breakpoints remain unclear.

Purpose of the Study:

  • To establish a genetic system for detecting MHMR events following DNA double-strand breaks (DSBs).
  • To elucidate the genetic pathways and requirements for MHMR with varying microhomology lengths.

Main Methods:

  • Development of a simple genetic system in budding yeast to study DSB repair.
  • Analysis of MHMR requirements, including the role of Pol32 and DNA synthesis.
  • Comparison of repair efficiency for different microhomology lengths and break distances.

Main Results:

  • MHMR using >15 bp microhomology functions as a single-strand annealing variant dependent on Pol32.
  • MHMR is sensitive to sequence mismatches and does not require extensive DNA synthesis.
  • Shorter microhomology (<14 bp) involves a distinct, less efficient pathway for distant DSBs.
  • MHMR efficiently mediates chromosomal translocations, comparable to intra-chromosomal repair.

Conclusions:

  • The inherent annealing of microhomology sequences is a key driver of chromosomal rearrangements.
  • Understanding MHMR pathways is crucial for comprehending the etiology of genetic diseases and carcinogenesis.

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