HARVARD MEDICAL SCHOOL
Department of Microbiology
and Molecular Genetics

1920

    

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September 6, 1994

Dr. Joshua Lederberg
The Rockefeller University
New York, NY 10021-6399

Dear Joshua,

I am responding to your questions about Jac. Overexpression of LacY is harmful
or lethal to cells. However, this is particularly true of membrane proteins, in general,
and probably not peculiar to Lac. I don’t know of any studies on whether lactose itself
might make things worse. Benno Muller-Hill has a number of papers on overexpression
of LacY and Tom Wilson has also found lethality associated with it. Overexpression of
LacZ has not been associated with any deleterious effects that I know of.

We have in our collection the set of mapping deletions for lacZ. We haven’t
worked with them in a long time, so I don’t know what shape they’re in.

Thanks for the reprints. I love seeing the old papers.

Jon Beckwith )