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Mis-targeting of multiple gene disruption constructs containing hisG
1Department of Cancer Cell Biology, Harvard School of Public Health, Boston, MA 02115, USA.
Current Genetics
|December 29, 2000
Summary
Efficient gene targeting in Saccharomyces cerevisiae requires sufficient homology. Internal homologous sequences, like hisG, significantly reduce integration efficiency when targeting constructs have limited homology, impacting methods like PCR-mediated gene targeting.
Area of Science:
- Molecular Biology
- Yeast Genetics
Background:
- Homologous recombination is a key mechanism for gene targeting in Saccharomyces cerevisiae.
- The hisG cassette is frequently used for gene disruptions, allowing marker recovery but leaving residual sequences.
Purpose of the Study:
- To investigate the impact of endogenous homologous sequences on gene targeting efficiency.
- To determine the effect of limited homology in targeting constructs when competing with internal homologous sequences.
Main Methods:
- Utilizing an integration construct with limited homology at one end for gene targeting in yeast.
- Comparing integration efficiency with varying numbers of endogenous hisG sequences (0, 1, or 2 copies).
- Assessing the effect of enlarged homology at the disruption construct.
Main Results:
- A single genomic hisG copy reduced target integration from 44% to 4.5%.
- Two genomic hisG copies decreased integration efficiency to below 1%.
- Increasing homology at the disruption construct abolished the inhibitory effect of endogenous hisG.
Conclusions:
- Competition between endogenous hisG sequences and targeting constructs with limited homology significantly impairs gene targeting efficiency.
- Methods relying on limited homology, such as PCR-mediated gene targeting, are less effective in the presence of substantial internal homologous sequences.
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