restriction enzymes

Ashok Aiyar aiyar at
Mon Aug 3 09:26:35 EST 1998

On 3 Aug 1998 09:09:28 GMT, Chris Boyd <chrisb at> wrote:
>Where is your evidence for this assertion?  I'd be surprised if
>dam-methylation were present in more than a minority of species outside
>the Enterobacteriacae.

You're right, I don't have evidence that the genomic DNA of most
eubacteria is dam-methylated.  What I do know is that the DNA of
Escherichia coli and Serratia marcescens is methylated, and that 
dam methylases have been cloned, functionally or by sequence 
identity (or both), from several other taxa including Serratia, 
Salmonella, Haemophilus, Moraxella, Methanococcus, Porphyromonas, 
Streptococcus, Lactococcus, Treponema. and a few others.  Some of the
taxa that I have listed are enterobacteria (Escherichia, Serratia,
Salmonella), but all the others are not, indicating that this enzymatic
activity is rather widely distributed among eubacterial species.

Ashok Aiyar, Ph.D.
McArdle Laboratory for Cancer Research
aiyar at

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