Werner Arber on Restrictor Enzymes
  Werner Arber     Biography    
Recorded: 08 May 2012

Well then I was a post-doc in the United States, and came back in 1960, and interestingly I was not—had no idea to go into restriction systems, but in fact I had, and was paid for several years by this large credit in Switzerland for developing atomic power plants. And our study was not in the physical side, but in the biological side, to make risk evaluation of how do irradiations work on microorganisms.

1960. And I decided to work with some bacterial strains with which I did not work before, but of which other people had found radiation resistant mutants. So, I wanted to include these strains. And my viruses, which was adapted to K strains, finally they’d grown only very badly in B strains. Which were these, having the radiation resistance. And I knew that some years before several other groups had studied so-called host controlled modification, and I immediately thought that that may be this phenomenon. And indeed, when you adapted the phage first to B strains they grew well. And I was very curious. I felt this would be a way to find out how host controlled modification functions. And, I must remember that at that moment everybody talked on semiconservative DNA modification, which had been, the work, in important publications, for example Meselson-Stahl, on that, and I wondered whether—DNA got the modification, rather than that the virus would pick up the host gene which would allow a host gene product. Which would allow the virus to infect bacteria again, and it turned out that indeed I was right. The modification was on DNA, in fact from nowadays point of view this we know that this is methylation, a phenomenon which nowadays is called epigenetics. And at that moment, of course, it was rather new. One knew that some DNA gets methylated but no one talked yet on epigenetics at that moment.

Werner Arber, (born June 3, 1929, Gränichen, Switz.), Swiss microbiologist, corecipient with Daniel Nathans and Hamilton Othanel Smith of the United States of the Nobel Prize for Physiology or Medicine for 1978. All three were cited for their work in molecular genetics, specifically the discovery and application of enzymes that break the giant molecules of deoxyribonucleic acid (DNA) into manageable pieces, small enough to be separated for individual study but large enough to retain bits of the genetic information inherent in the sequence of units that make up the original substance. Arber studied at the Swiss Federal Institute of Technology in Zürich, the University of Geneva, and the University of Southern California. He served on the faculty at Geneva from 1960 to 1970, when he became professor of microbiology at the University of Basel. During the late 1950s and early ’60s Arber and several others extended the work of an earlier Nobel laureate, Salvador Luria, who had observed that bacteriophages (viruses that infect bacteria) not only induce hereditary mutations in their bacterial hosts but at the same time undergo hereditary mutations themselves. Arber’s research was concentrated on the action of protective enzymes present in the bacteria, which modify the DNA of the infecting virus—e.g., the restriction enzyme, so-called for its ability to restrict the growth of the bacteriophage by cutting the molecule of its DNA to pieces.