UNIVERSITY OF EDINBURGH Biochemistry Unit,

Telephone 42080 rin Atel
Frof. Lederberg, Edinburgh 9.

Department of Genetics,
College of Asriculture,
University of Wisconsin,
liadison, 6,
wisconsin, th
U.S.A. October 15°™ 1956.

Dear i.rof. Lederberg,

Thank you for your interesting letter
Enclosed is the manuscript of a paper that I read
4."
2 ty yy
and a few reprints descridins some earlier work on the penicillin

~"

of October 12°",

at the Symposium on Antibiotics held in Milan September 10

problen. We also have a paper in the press on the "“autolytic"
vrotoplast formation in staphylococci which will apvear in the
Journal of General -icrobiolozy vol. 16, No. l. By "autolysis”
we mean the reversal of the processes of synthesis. ‘Je observe,
for instance,that the cell walls isolated fron stapiylococci (that
have been harvested from rapidly growine cultures)will spontaneously
divest themselves if placed in a mediua at appropriate ionic strength
and pH: they also digest themselves under the same conditions
when they are still in situ round the intact protoplast of the
staphylococcus provided that the protoplast is crotected by the
presence of very high concentrations of sucrose. ‘Ve have used the
term "autolysis" to mean svontaneous degradation without reference
to whether the cell is "dead" or not. 7@ would not like to attempt
to define tle word "dead".

Iwas very interested by your renerEs about the “L-forus"', especially
as Jeibull suvzested in the Symeosium on Sacterial Anatomy eld by
the Society for General iicrobiolosy last April tiat the HL—~forns”
misht be naked protoplasts. It is most interostins, therefore, that
you have succeeded in getting an "L" srowth of your coli protoplasts.

As you probably know, MeQuillen has obtsined a kind of proliferation
of protoplasts of B, nezaterium which seens to be by budding instead
of ae fission. I an abem enclosing
on she 5 possible reason for the diffefent mode of division in
oroboslast and intact cell.

as to the "weird mixture" of malonate and arabinose, I cannot sce.

a speculative little note

1.1

that this is weirder then penicillin ard sucrose! The reason for
using arabinose is that it is not metabolised end does not yvenetrate
the plasma-membrane rapidly. <.alonate may be substituted Dy a
number of other salts at the same ionic strensth, but ualonate

seems to work best, partly I Le ee because it helps to inhibit

residual ressiretion, but ma. y because it cannot penetrate the
membrane and acts as yuite a 008 purfer. here Ls vothing navical

about it —— at leas a no nore magical tian penicillin!

.

I still feel that the mechenism of ection of penLleiliin i

a
Oo
cr

completely oxpleined. For one thins, in experiments that we hove

he.

been doing for the last year, we have not been successful in preparing
protoplasts of sram-positive penicillin-sensitive bacteria as you
have been able to do with the "“penicillin-—~insensitive’ coli. Tere
uay be experinental reasons for this failure, but at present we
are unable to tauink waat. they may be.

I will let you snow of any further development of our vor's alons
these lines as it comes to hand, and I shall be nost interested to
hear about your progress in return.

Yours sincerely,