DH5 alpha

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Alternate Names

fhuA2 lac(del)U169 phoA glnV44 Φ80' lacZ(del)M15 gyrA96 recA1 relA1 endA1 thi-1 hsdR17

slow growth

Transforms with high efficiency. Like many cloning strains, DH5 alpha has several features that make it useful for recombinant DNA methods.

The endA1 mutation inactivates an intracellular endonuclease that degrades plasmid DNA in many miniprep methods^[1].
The hsdR17 mutation eliminates the restriction endonuclease of the EcoKI restriction-modification system, so DNA lacking the EcoKI methylation will not be degraded. DNA prepared from hsdR strains that are wt for hsdM will be methylated and can be used to transform wt E. coli K-12 strains.
Δ(lacZ)M15 is the alpha acceptor allele needed for blue-white screening with many lacZ based vectors.
recA eliminates homologous recombination. This makes the strain somewhat sickly, but reduces deletion formation and plasmid multimerization^[2].
glnV44 is the systematic name for SupE44, an amber suppressor

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↑ Taylor, RG et al. (1993) E. coli host strains significantly affect the quality of small scale plasmid DNA preparations used for sequencing. Nucleic Acids Res. 21 1677-8 PubMed
↑ citation needed