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This Week’s Citation Classic
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CC/NUMBER 19
Cohen.Bazlre G, Sistrom W R & Stanier R Y. Kinetic studies of pigment synthesis
by non-sulfur purple bacteria. J. Cell. Comp. Phy.niol. 49:25-68. 1957.
IDepartment of Bacteriology. University of California. Berkeley, CA!
bically, devoid of pigments, did not contain
such particles. The problem was laid out and
Stanier hoped that through my experience
with /3-galactosidase, I would be able to
tackle the regulation of pigment and chromatophore synthesis in purple bacteria.
On arrival in Berkeley in September 1953,
I chose a strain of Rhodopseuclomonas
spheroides, from the collection of purple
bacteria of van Niel, and started growing it
photosynthetically and aerobically. The first
semiquantitative experiments gave the clue:
the bacteria reacted to an increase or a decrease in light intensity by immediately adjusting the rate of photosynthetic pigment
Germaine Cohen-Bazire
Unite de Physiologie Microbienne
synthesis to that corresponding to the light
Departement de Biochimie
intensity at which they were exposed during
et Genetique Mol~culaire
growth. For cells that had a higher initial
Institut Pasteur
pigment content than that required by the
75015 Paris
new level of light, adjustment was achieved
France
by a temporary arrest of pigment synthesis
and dilution through growth. For cells with a
lower pigment content than that required,
April 2, 1985
adjustment was achieved by a temporary
rapid pigment synthesis to the proper level.
In 1 his monograph on the Athiorhoda- Thereafter, the differential rates of pigment
ceae, C.B. van Niel had summarized the in- synthesis were identical for the two cultures.
formation concerning the color changes ob- Aeration of a photosynthetically growing
served in cultures of members of this bacte- culture provoked an immediate arrest of
rial group. He wrote, “The most striking ef- bacteriochlorophyll (Bchl) synthesis and a
fects are no doubt exerted by light and oxy- strong inhibition of carotenoid synthesis.
gen.... No careful quantitative studies have
These experiments were repeated with accuyet been made on the pigments of Athiorho- rate measurements of the Bchl and caroldaceae.” The work published in 1957 by
enoid cell contents.
W.R. Sistrom, R.Y. Stanier, and me tried to
It was evident that an increase in light inremedy this situation.
tensity or the introduction of air elicited the
The experiments were performed during a
same response, a transitory one for light, a
postdoctoral year spent in Berkeley in
long-lasting effect for oxygenation. We pro1953-1954 in Stanier’s laboratory. I had met
posed that in the pathway of Bchl synthesis,
Stanier in 1952 at the Pasteur Institute in
a step was sensitive to the redox state of a
Paris. I was then working in Monod’s group
carrier in the electron transport system that
on /3-galactosidase 2biosynthesis. We had just
was common to both photosynthetic and oxpublished a paper where we defined the
idative metabolisms. One possible candi“differential rate of enzyme synthesis.”
date was the key enzyme d-aminolevulinate
Shortly before his Paris visit, Stanier, with
(ALA)-synthase. The activity of this enzyme
his Berkeley colleagues H.K. Schachman
has recently been shown to be regulated by
and A.B. Pardee, had discovered that the
the dithiol-disulfide interchange
mediated
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photosynthetic pigments of R. rubrum were
by the thioredoxin system. The mysterious
carried by large 3f200S) particles named
redox control may end up to be a thiol-redox
“chromatophores.” Cultures grown aero- control.
This paper describes methods for the quantitative
measurement of chlorophyll and carotenoids in
two Strains of nonsulfur purple bacteria. Rhodopseudomorias spheroides and Rhodospirillum
rubrum, and the application of these methods to
the study of the kinetics of photosynthetic pigment
5 synthesis under controlled conditions. [The
SCI indicates that this paper has been cited in
over 675 publications since 1957.]
I. v.n Ni.I C B. The culture, general phvstologv. morphology, and classification of the non-sulfur purple and brown
bacteria. Bacte,’io!. Re,, 8:1-118. 944. Cited 190 times since 195.5.i
2. Monod 1. Pappenbelmer A M. Jr. & Cohen-Baum 0. La cin(tique de Ia biosynth~sede Ia (3-galactosidase chez
E. you consid~rfecomme fonction de Ia croissance. Biochim. Biopttvt. Ama 9:648-60. 1952.
Cited 185 times since l955.~
3. Pardee A B. Schachnian H K & Siankr R Y. The chromalophores of Rhodospirillun, ,-ubrtrn,.
Nature 169:282-4, 1952. Cited 40 times since t955,i
4. CI~meni-M~teaI
I D & Holnigeen A. Purification and some properties of thioredonin from a photosynthetic
bacterium: Rhodopseudon~onasspheroides Y. iQadal P. cdi Thioredoxins. structure and functions.
Paris: Editions du Centre National de Ia Recherche Scientifique. 1983. p. 59-68.
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