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E. coli strain TB1 vs JM83 - Question about the hsdR mutation in TB1 (Jan/19/2010 )

Hello everyone,

I have a question about the genotype of E. coli strain TB1. The difference between TB1 and JM83 is that TB1 contains a hsdR mutation, which makes it restriction deficient. This means that it doesn't restrict DNA that is inserted during a cloning procedure, right? However, it seems to me that this is an ESSENTIAL feature of any E. coli host. But JM83 does NOT contain this mutation and is used regularly as a host for molecular cloning.

So my question is: what does the hsdR mutation exactly confer to TB1 that makes it a better host than JM83?



the hsdR mutation allows the efficient transformation of unmethylated DNA, e.g. from PCR amplifications.