The isolation of the lac repressor was a real challenge. In 1960, when the paper postulating its existence(’) appeared, I was a graduate student in the chemistry department of the University of Freiburg in Germany. My thesis adviser was Kurt Wallenfels, an organic chemist with a deep interest in glycosides and glycosidases. The subject of my work was the active sites of Pgalactosidase of E. coli. We therefore followed Monod’s work closely. As it happened, Freiburg, where I was brought up, was in the French Zone of occupied Germany and in consequence I and most of the other south German students could read French. So we read Monod’s Comptes Rendus paper(’) right after it came out. I remember well the discussion which followed in the group. Some of us loved the impeccable logic of it, while others thought that it was detached from any reality. Wallenfels invited Monod to give two lectures in Freiburg at this time, providing the chance to see and hear the impressive man. ‘Nature works in a Cartesian and not in a Hegelian manner’, he began his lecture. I doubted that, but was not the repressor a wonderful problem? The year 1961 brought the landmark English language paper from the Pasteur group with all the evidence for the existence of the lac and lambda repressors.(*) Almost simultaneously the review in the Cold Spring Harbor Symposium appeared.(3) There Jacob and Monod made a bold proposal. They postulated that the lac repressor was indeed the mRNA itself from the lac I gene. The proposal was based upon an unconvincing experiment which seemed to indicate that lac re ressor could be formed in the absence of tryptophanY4) But what if the repressor did not contain tryptophan or if it contained just one or two residues and thereby escaped the block? If lac repressor was indeed mRNA, then the recognition of lac operator might be explained by formation of a triple RNA-DNA helix . ( 5 ) I finished my PhD thesis at the beginning of 1962just when Wallenfels obtained a NATO Grant for a collaboration with Howard Rickenberg at Indiana University. Rickenberg had earlier been a postdoc at the Pasteur and had discovered there lac permease(@,the product of the lac Y gene which transports lactose and other galactosides into the E. coli cell. Wallenfels was con-
vinced that lac permease and Pgalactosidase were actually the same and he asked me to go to Rickenberg’s lab to prove his theory. This put me in an embarassing situation. I knew that his theory did not make any sense; the genetic evidence against it was overwhelming. It was simply his intuition which suggested the identity of these two proteins. Another collaborator had told Wallenfels previously that he did not want to work on this unsound idea - and he was asked to quit the laboratory. I therefore agreed to work on the problem but knew that I had to find a different, and solvable problem instead. One possibility was suggested by the fact that several people in the Wallenfels lab had synthesized many exotic glycosides over the previous few years. I decided, therefore, to take samples with me and use them to study the inducer specificity of lac repressor. The more refined the specificity proved to be the less likely would be the case that the repressor was an mRNA molecule. I arrived in January 1963 in Bloomington. I told Howard of my plan to study the specificity of induction in detail. He agreed. So I unpacked my sugars and began working. It quickly became evident that lac repressor showed a very refined specificity towards inducers. Indeed, 1 discovered a new class of antiinducers which bind tightly to repressor but which block induction. The properties of the various sugars could be used to select constitutives and the inducible wild type.(’) All this suggested that lac repressor was a protein but the project for its isolation remained as distant as ever. I was pretty isolated during my two years in Bloomington and most ‘discussions’ of the problem were with myself. I tried to affinity label lac repressor in vivo with a particular inducer, but the experiment failed. I was determined to continue. But where? In 1965 I went to New York to the International Congress of Biochemistry to look for a job. I wanted to leave my Midwestern isolation in order to go to the best possible laboratory. But which one was this? One possibility I thought about was Jim Watson’s lab at Harvard. When I went to his lecture on ribosomes (which did not interest me) I found it impossible to enter the hall, which was packed. Instead I wandered off through the building, daydreaming. And suddenly I saw Jim Watson directly in front of me, alone, scratching his head. I made the instantaneous decision to ask him for a job. He asked me what I had done before. I told him that I had worked on lac repressor and that I was interested in isolating it. I also told him about my failure. He said that there was somebody in his lab, Wally Gilbert, who might possibly be interested in taking me on. Wally Gilbert was out of town but he would be back in four weeks. It so happened that I had arranged to go for six weeks to Adelberg’s lab to learn the tricks of bacterial genetics from Herb Boyer. I therefore said that Dr. Gilbert could call me in Yale and I would come to Cambridge for an interview.
Wally Gilbert called, I drove to Harvard and we met. I told him all that I had done and all that I knew about the lac repressor. He told me that he had also tried to isolate it, namely via its DNA binding capacity and that he had failed too. Then he told me that he would hire me. I was so happy. I drove back to New Haven and from there to Bloomington, finished my time there, then drove back to Cambridge and work began. In the first few months I had less than a square meter of deskspace in the lab next to a student, Jerry Adams. I did not mind. The first thing Wally and I did was to set out to define the problem in a rigorous manner. Was lac repressor really a protein? The inducer specificity suggested it, but rigorous proof would be better. Wally suggested a simple way to get nonsense mutants in the I gene. It worked like a charm.(*) The whole atmosphere in the lab was electrifying. Jim Watson, who was visible all day, was a challenge in himself. He had done the best possible piece of work by elucidating the DNA structure. He knew what was going on in Molecular Biology and he had an intense feeling for the direction things were going. But at the same time, he was far away. H e was interested in the repressor problem and its solution but not in the way one might do it. It took me one sentence to tell him that I had isolated two nonsense mutants of the lac Z gene and that this showed that the lac repressor was indeed a protein. ‘Good’ he said, and disappeared. With Klaus Weber, another German postdoc, I had a kind of playful competition as to how many minutes of total conversation with Jim we both could claim. After a year or so he had totalled 22 minutes while I was dragging behind with 17 minutes. That was Jim. Wally was totally different. H e still had his position in physics. H e had published an elegant paper on ribosomes and was coauthor of the mRNA paper. He was in the lab day and night and always had time for technical or theoretical discussions. Never before or since have 1 seen anyone who so liked discussing experiments and doing new ones. It was just wonderful to discuss experiments with Wally. The structure of the lab was totally different from any other lab I had previously known or have seen since. Jim guided it like a godfather from an immense distance. He did not put his name on any of the papers his graduate students or postdocs produced. He certainly didn’t need it any more. Wally - who cared about the experimental details of all of these students - did not put his name on their papers either. I still feel uneasy when I think that he was not listed as a coauthor on my little paper describing nonsense mutations in the lac I gene. His proud refusal to acknowledge that he might possibly need coauthorship on these papers to get tenure was most disquieting. This was the time of the Vietnam war and many of the students and the younger faculty were against it. One day I met Jon Beckwith and David Zipser in a demonstration and we marched side by side down Massachusetts Avenue. Jon told me the news about a
lambda h80dlac phage, which I did not know about and during most of this demonstration we talked about lac and lambda. I liked that - it made the demonstration doubly useful; we showed our rejection of this unjust war and used the time productively to talk science. Nevertheless all these discussions did not make me lose sight of the fact that we did not have the lac repressor, and that, if we did not get it, that was it. Furthermore we knew that we were not alone in the search. Other people were trying too. In particular at the Pasteur a real effort was being made. One funny moment came later when I found an article in a German journal which claimed the isolation of lac repressor - in fact the authors had isolated hosphorylated inducer isopropyl-thio-PD-galactoside(B). However, it was less funny to be told the news one day by the protein chemist Gary Craven that he had seen experiments from Ethan Signer in Paris indicating the succesful isolation of the lac repressor. ‘Give it up, Benno, it’s all over’ he said smiling. Signer supposedly had found lac repressor bound to the DNA in lambda dh80dlac phage grown in bacteria in the absence but not in the presence of IPTG. Later it turned out that the results could not be repeated. And then there was Mark Ptashne working in the same building, one floor up, on the isolation of lambda repressor. While this was a totally different system, the goal was the same. Who would be first? His approach was so different that on the technical side there was no competition and no possible interference. It so ha pened that he solved his problem directly after us. Wally and I spent a great deal of time trying to define the repressor problem quantitatively. How many molecules were in one cell? How much protein did this amount to? How many molecules had to be there if one wanted to use a particular technique to detect lac repressor? What was the binding constant of the best gratuitous inducer IPTG? What was the binding constant to lac operator inside the cell? Which effects could one use in which manner? Wally even gave seminars on this topic, which were most lucid, but of course all negative. A property we could use was inducer binding. It could be tested in vitro. Klaus Weber who had also originated from the Wallenfels laboratory, suggested we might try equilibrium dialysis to detect a protein fraction from i+ extracts which would bind inducer. The question then was which inducer was the best to try. Apparently galactosido-glycerol fulfilled this requirement. It induced Y - (permease negative) strains at a concentration of lop9M. So Wally set out to synthesize radioactive galactosido-glycerol. When he had it we realized that galactosido-glycerol was in fact a poor inducer in terms of repressor binding. It was simply accumulated in high concentration even in Y - cells by the galactose transport systems. Just at the moment when we realized that galactosido-glycerol was of no use, the best gratuitous lac inducer, IPTG, became commercially available labelled with 35S.But our calcu-
(18-
lations indicated that the binding constant of 2 ~ 1 0 stay ~ at~ Harvard. How things continued is not part of this article but I would just like to close with one anecdote. 1 was a hundred times too low to detect binding in a crude had come back to the Biolabs in the autumn of 1966 to extract. try - in vain - to show that lac repressor inhibited in I saw two possibilities to solve the problem: either to vitro lac transcription. One day, late in the afternoon, I isolate a repressor mutant which bound IPTG ten times saw Monod standing in the door. ‘Hello’ he said. ‘Hello’ tighter or to isolate an overproducer which made ten I answered. And then he simply said ‘Benno, after all it times more. The second possibility seemed then out of reach. In fact it was not. Later in ’67 I isolated such a was pedestrian’, bowed and disappeared, leaving me mutant(”). But at that time 1 concentrated on the first baffled for a long time. Now, many years later, I like to interpret his comment as ‘slow, down to earth, with possibility. 1 had already played in Bloomington with only a few technical crutches’ and think it was, after all, a technique which might allow one to isolate such a a compliment. mutant: E. coli cells which are fully induced need a lower concentration of inducer to stay induced than to get induced(12). This phenomenon is explained by the existence of lac permease, which when present will References pump inducer into the cell. I had to get a mutant which 1 JACOB, F . , PERRIN,D., SANCHEZ,C. AND MONOD,J . (1960). L‘Operon: Groupe de genes expression coordennke par un operateur. C. R . Hebd. could be induced at a lower inducer concentration. In Sceance Acad. Sci. Paris 250, 1127-1729. retrospect it was a risky manoeuver, but against all 2 JACOB, F. AND MONOD, J. (1961). Genetic regulatory mechanisms in the pessimistic expectations it worked. I isolated a mutant synthesis of proteins. 1. Mol. B i d . 3 , 318-356. 3 JACOB, F. AND MONOD, J. (1961). On the regulation of gene activity. Cold which indeed could be induced by a lower concenSpring Harbor Symp. Quant. Biol. 26, 193-209. tration of IPTG than the wild-type strain. I gave the 4 PARDEE,A. B . AND PwsnDcE, L. S. (1959). On the nature of the repressor of mutant to Wally and he did the equilibrium dialysis Pgalactosidase synthesis in Escherichia coli. Biochem. Biophys. Acfa 36, 545-547. experiments on its crude extracts and ammonium sul5 MILLER,J. H . AND SOBELL,H . M. (1966). A molecular model for gene fate fractions. These worked immediately: IPTG bindrepression. Proc. Nut1 Acad. Sci. LISA 55, 1201-1205. 6 RICKENBERG, H. V.,COHEN, G. N.,BUITIN, G. AND MONOD,J . (1956). La ing activity was found where it should be but it was galactoside-permease d’Escherichiacoli. Ann. Inst. Pasteur 91, 829-857. absent where it should be absent (in I- or F extracts). 7 MULLER-HILL, B . , RICKENBERG, H . V. AND WALLENFELS, K. (1964). We had isolated the lac repressor! Wally wrote the Specificity of the induction of the enzymes of the lac operon in Escherichia colt. J. Mol. Biol. 10, 303-318. paper which Jim then submitted to PNAS(13). It so 8 MULLER-HILL, B. (1966). Supressible regulatory constitutive mutants of the happened that the Cold Spring Harbor Symposium 1966 lactose system of Escherichia coli. J. Mol. Biol. 15, 374-376. was taking place just as we were getting our first results. 9 LODEMANN, E., DRAHOVSKY, D., FLOHL,R. AND WACKER, A. (1967). Uber die spezifische Bindung von TMG in E. coli. Z.f. Nururforschung 22b, 301-306. We drove down and attended as spectators. Wally did 1 0 RASHNE, M. (1967). Isolation of the 1 phage repressor. Proc. Natl Acad. not talk, we just informally told the news in the Sci. USA 57,306-313. 11 MULLER-HILL, B . , CRAPO, L. AND GILBERT, W. (1968). Mutants that make intermissions and during the spectacle Jim had set up to more lac repressor. Proc. Narl Acad. Sci. USA 59, 1259-1264. honour Francis Crick at his 50th birthday: He had to 12 NOVICK,A. AND WEINER,M. (1957). Enzyme induction, an all or none open a box, and out of the box came an almost naked phenomenon. Proc. Natl Acad. Sci. USA 43,553-566. 1 3 GILBERT, W. AND MOLLER-HILL, B . (1966). Isolation of the lac repressor. New York model to kiss him. Proc. Narl Acad. Sci. USA 56, 1891-1898. I then went on vacation, home to Freiburg. Wallenfels arranged a seminar and proposed that I might use Benno Miiller-Hill is at the Institut fiir Genetik der the lac repressor work for my habilitation (to become Universitat zu Koln, Weyertal 121, D 5000 Koln 41, an assistant professor). But the faculty did not like the FRG. work, a most fortunate failure, because it allowed me to
vinced that lac permease and Pgalactosidase were actually the same and he asked me to go to Rickenberg’s lab to prove his theory. This put me in an embarassing situation. I knew that his theory did not make any sense; the genetic evidence against it was overwhelming. It was simply his intuition which suggested the identity of these two proteins. Another collaborator had told Wallenfels previously that he did not want to work on this unsound idea - and he was asked to quit the laboratory. I therefore agreed to work on the problem but knew that I had to find a different, and solvable problem instead. One possibility was suggested by the fact that several people in the Wallenfels lab had synthesized many exotic glycosides over the previous few years. I decided, therefore, to take samples with me and use them to study the inducer specificity of lac repressor. The more refined the specificity proved to be the less likely would be the case that the repressor was an mRNA molecule. I arrived in January 1963 in Bloomington. I told Howard of my plan to study the specificity of induction in detail. He agreed. So I unpacked my sugars and began working. It quickly became evident that lac repressor showed a very refined specificity towards inducers. Indeed, 1 discovered a new class of antiinducers which bind tightly to repressor but which block induction. The properties of the various sugars could be used to select constitutives and the inducible wild type.(’) All this suggested that lac repressor was a protein but the project for its isolation remained as distant as ever. I was pretty isolated during my two years in Bloomington and most ‘discussions’ of the problem were with myself. I tried to affinity label lac repressor in vivo with a particular inducer, but the experiment failed. I was determined to continue. But where? In 1965 I went to New York to the International Congress of Biochemistry to look for a job. I wanted to leave my Midwestern isolation in order to go to the best possible laboratory. But which one was this? One possibility I thought about was Jim Watson’s lab at Harvard. When I went to his lecture on ribosomes (which did not interest me) I found it impossible to enter the hall, which was packed. Instead I wandered off through the building, daydreaming. And suddenly I saw Jim Watson directly in front of me, alone, scratching his head. I made the instantaneous decision to ask him for a job. He asked me what I had done before. I told him that I had worked on lac repressor and that I was interested in isolating it. I also told him about my failure. He said that there was somebody in his lab, Wally Gilbert, who might possibly be interested in taking me on. Wally Gilbert was out of town but he would be back in four weeks. It so happened that I had arranged to go for six weeks to Adelberg’s lab to learn the tricks of bacterial genetics from Herb Boyer. I therefore said that Dr. Gilbert could call me in Yale and I would come to Cambridge for an interview.
Wally Gilbert called, I drove to Harvard and we met. I told him all that I had done and all that I knew about the lac repressor. He told me that he had also tried to isolate it, namely via its DNA binding capacity and that he had failed too. Then he told me that he would hire me. I was so happy. I drove back to New Haven and from there to Bloomington, finished my time there, then drove back to Cambridge and work began. In the first few months I had less than a square meter of deskspace in the lab next to a student, Jerry Adams. I did not mind. The first thing Wally and I did was to set out to define the problem in a rigorous manner. Was lac repressor really a protein? The inducer specificity suggested it, but rigorous proof would be better. Wally suggested a simple way to get nonsense mutants in the I gene. It worked like a charm.(*) The whole atmosphere in the lab was electrifying. Jim Watson, who was visible all day, was a challenge in himself. He had done the best possible piece of work by elucidating the DNA structure. He knew what was going on in Molecular Biology and he had an intense feeling for the direction things were going. But at the same time, he was far away. H e was interested in the repressor problem and its solution but not in the way one might do it. It took me one sentence to tell him that I had isolated two nonsense mutants of the lac Z gene and that this showed that the lac repressor was indeed a protein. ‘Good’ he said, and disappeared. With Klaus Weber, another German postdoc, I had a kind of playful competition as to how many minutes of total conversation with Jim we both could claim. After a year or so he had totalled 22 minutes while I was dragging behind with 17 minutes. That was Jim. Wally was totally different. H e still had his position in physics. H e had published an elegant paper on ribosomes and was coauthor of the mRNA paper. He was in the lab day and night and always had time for technical or theoretical discussions. Never before or since have 1 seen anyone who so liked discussing experiments and doing new ones. It was just wonderful to discuss experiments with Wally. The structure of the lab was totally different from any other lab I had previously known or have seen since. Jim guided it like a godfather from an immense distance. He did not put his name on any of the papers his graduate students or postdocs produced. He certainly didn’t need it any more. Wally - who cared about the experimental details of all of these students - did not put his name on their papers either. I still feel uneasy when I think that he was not listed as a coauthor on my little paper describing nonsense mutations in the lac I gene. His proud refusal to acknowledge that he might possibly need coauthorship on these papers to get tenure was most disquieting. This was the time of the Vietnam war and many of the students and the younger faculty were against it. One day I met Jon Beckwith and David Zipser in a demonstration and we marched side by side down Massachusetts Avenue. Jon told me the news about a
lambda h80dlac phage, which I did not know about and during most of this demonstration we talked about lac and lambda. I liked that - it made the demonstration doubly useful; we showed our rejection of this unjust war and used the time productively to talk science. Nevertheless all these discussions did not make me lose sight of the fact that we did not have the lac repressor, and that, if we did not get it, that was it. Furthermore we knew that we were not alone in the search. Other people were trying too. In particular at the Pasteur a real effort was being made. One funny moment came later when I found an article in a German journal which claimed the isolation of lac repressor - in fact the authors had isolated hosphorylated inducer isopropyl-thio-PD-galactoside(B). However, it was less funny to be told the news one day by the protein chemist Gary Craven that he had seen experiments from Ethan Signer in Paris indicating the succesful isolation of the lac repressor. ‘Give it up, Benno, it’s all over’ he said smiling. Signer supposedly had found lac repressor bound to the DNA in lambda dh80dlac phage grown in bacteria in the absence but not in the presence of IPTG. Later it turned out that the results could not be repeated. And then there was Mark Ptashne working in the same building, one floor up, on the isolation of lambda repressor. While this was a totally different system, the goal was the same. Who would be first? His approach was so different that on the technical side there was no competition and no possible interference. It so ha pened that he solved his problem directly after us. Wally and I spent a great deal of time trying to define the repressor problem quantitatively. How many molecules were in one cell? How much protein did this amount to? How many molecules had to be there if one wanted to use a particular technique to detect lac repressor? What was the binding constant of the best gratuitous inducer IPTG? What was the binding constant to lac operator inside the cell? Which effects could one use in which manner? Wally even gave seminars on this topic, which were most lucid, but of course all negative. A property we could use was inducer binding. It could be tested in vitro. Klaus Weber who had also originated from the Wallenfels laboratory, suggested we might try equilibrium dialysis to detect a protein fraction from i+ extracts which would bind inducer. The question then was which inducer was the best to try. Apparently galactosido-glycerol fulfilled this requirement. It induced Y - (permease negative) strains at a concentration of lop9M. So Wally set out to synthesize radioactive galactosido-glycerol. When he had it we realized that galactosido-glycerol was in fact a poor inducer in terms of repressor binding. It was simply accumulated in high concentration even in Y - cells by the galactose transport systems. Just at the moment when we realized that galactosido-glycerol was of no use, the best gratuitous lac inducer, IPTG, became commercially available labelled with 35S.But our calcu-
(18-
lations indicated that the binding constant of 2 ~ 1 0 stay ~ at~ Harvard. How things continued is not part of this article but I would just like to close with one anecdote. 1 was a hundred times too low to detect binding in a crude had come back to the Biolabs in the autumn of 1966 to extract. try - in vain - to show that lac repressor inhibited in I saw two possibilities to solve the problem: either to vitro lac transcription. One day, late in the afternoon, I isolate a repressor mutant which bound IPTG ten times saw Monod standing in the door. ‘Hello’ he said. ‘Hello’ tighter or to isolate an overproducer which made ten I answered. And then he simply said ‘Benno, after all it times more. The second possibility seemed then out of reach. In fact it was not. Later in ’67 I isolated such a was pedestrian’, bowed and disappeared, leaving me mutant(”). But at that time 1 concentrated on the first baffled for a long time. Now, many years later, I like to interpret his comment as ‘slow, down to earth, with possibility. 1 had already played in Bloomington with only a few technical crutches’ and think it was, after all, a technique which might allow one to isolate such a a compliment. mutant: E. coli cells which are fully induced need a lower concentration of inducer to stay induced than to get induced(12). This phenomenon is explained by the existence of lac permease, which when present will References pump inducer into the cell. I had to get a mutant which 1 JACOB, F . , PERRIN,D., SANCHEZ,C. AND MONOD,J . (1960). L‘Operon: Groupe de genes expression coordennke par un operateur. C. R . Hebd. could be induced at a lower inducer concentration. In Sceance Acad. Sci. Paris 250, 1127-1729. retrospect it was a risky manoeuver, but against all 2 JACOB, F. AND MONOD, J. (1961). Genetic regulatory mechanisms in the pessimistic expectations it worked. I isolated a mutant synthesis of proteins. 1. Mol. B i d . 3 , 318-356. 3 JACOB, F. AND MONOD, J. (1961). On the regulation of gene activity. Cold which indeed could be induced by a lower concenSpring Harbor Symp. Quant. Biol. 26, 193-209. tration of IPTG than the wild-type strain. I gave the 4 PARDEE,A. B . AND PwsnDcE, L. S. (1959). On the nature of the repressor of mutant to Wally and he did the equilibrium dialysis Pgalactosidase synthesis in Escherichia coli. Biochem. Biophys. Acfa 36, 545-547. experiments on its crude extracts and ammonium sul5 MILLER,J. H . AND SOBELL,H . M. (1966). A molecular model for gene fate fractions. These worked immediately: IPTG bindrepression. Proc. Nut1 Acad. Sci. LISA 55, 1201-1205. 6 RICKENBERG, H. V.,COHEN, G. N.,BUITIN, G. AND MONOD,J . (1956). La ing activity was found where it should be but it was galactoside-permease d’Escherichiacoli. Ann. Inst. Pasteur 91, 829-857. absent where it should be absent (in I- or F extracts). 7 MULLER-HILL, B . , RICKENBERG, H . V. AND WALLENFELS, K. (1964). We had isolated the lac repressor! Wally wrote the Specificity of the induction of the enzymes of the lac operon in Escherichia colt. J. Mol. Biol. 10, 303-318. paper which Jim then submitted to PNAS(13). It so 8 MULLER-HILL, B. (1966). Supressible regulatory constitutive mutants of the happened that the Cold Spring Harbor Symposium 1966 lactose system of Escherichia coli. J. Mol. Biol. 15, 374-376. was taking place just as we were getting our first results. 9 LODEMANN, E., DRAHOVSKY, D., FLOHL,R. AND WACKER, A. (1967). Uber die spezifische Bindung von TMG in E. coli. Z.f. Nururforschung 22b, 301-306. We drove down and attended as spectators. Wally did 1 0 RASHNE, M. (1967). Isolation of the 1 phage repressor. Proc. Natl Acad. not talk, we just informally told the news in the Sci. USA 57,306-313. 11 MULLER-HILL, B . , CRAPO, L. AND GILBERT, W. (1968). Mutants that make intermissions and during the spectacle Jim had set up to more lac repressor. Proc. Narl Acad. Sci. USA 59, 1259-1264. honour Francis Crick at his 50th birthday: He had to 12 NOVICK,A. AND WEINER,M. (1957). Enzyme induction, an all or none open a box, and out of the box came an almost naked phenomenon. Proc. Natl Acad. Sci. USA 43,553-566. 1 3 GILBERT, W. AND MOLLER-HILL, B . (1966). Isolation of the lac repressor. New York model to kiss him. Proc. Narl Acad. Sci. USA 56, 1891-1898. I then went on vacation, home to Freiburg. Wallenfels arranged a seminar and proposed that I might use Benno Miiller-Hill is at the Institut fiir Genetik der the lac repressor work for my habilitation (to become Universitat zu Koln, Weyertal 121, D 5000 Koln 41, an assistant professor). But the faculty did not like the FRG. work, a most fortunate failure, because it allowed me to
