Congratulations Dr. Christian McCartney!

Tribute to Gordon H. Dixon

September 2018

Some background to “Protein Evolution Revisited” by Peter L. Davies* and Laurie Graham – published September 2018 (PMID: 30176752).

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In recognition of the lifework of Dr. Gordon H. Dixon (1930/03/25 – 2016/07/24), two of Gordon’s former trainees - Rafael Oliva and Stephen A. Krawetz - commissioned a Special Issue of Systems Biology in Reproductive Medicine in his memory. Peer-reviewed papers were contributed by researchers who trained in the Dixon lab, or were collaborators. The modified preface to our review (below) also gives an insight into how we came to work on antifreeze proteins.

Peter Davies:  Gordon H. Dixon (GHD), one of my post-doctoral mentors, wrote an inspiring review on “Mechanisms of Protein Evolution” in the 1966 2nd edition of ‘Essays in Biochemistry’. It was written only thirteen years after the discovery of double helix DNA structure, at a time when the genetic code had just been deciphered, nucleic acid sequencing was tortuous, and protein sequencing was THE way to study gene variation and mutation. GHD was able to capture the emerging field of molecular biology in this article and illustrate how protein evolutionary mechanisms were being deduced from tiny amounts of data. I read “Mechanisms of Protein Evolution” as an undergraduate student at University of Wales, UK and was fascinated by the emerging links between protein divergence and the evolution of species. GHD’s review encouraged me to continue the study of biochemistry at the graduate level, which led in turn to a career in research.  In 1968, I was accepted into the graduate program in the Department of Biochemistry at the University of British Columbia, not realizing that GHD had moved there from Toronto. When I found out he was in the department I was told Gordon’s lab was full. Indeed it was crowded, and I remember at one point a post-doctoral fellow using the ultracentrifuge as a desk, hoping that the rotors were well balanced. I made many friends in his lab and followed their work on rainbow trout spermatogenesis, histone modification and protamine expression with great interest.

My opportunity to work with Gordon came in 1974 as a post-doctoral fellow when GHD returned to Canada from Sussex, UK to set up a new lab at the University of Calgary’s Medical School next to the Foothills Hospital. By this time it was realized that eukaryotic messenger RNAs had poly (A) tails and the isolation of protamine mRNA had been achieved and perfected in the GHD lab by Lashitew Gedamu. One of the collaborative projects that I worked on with Lashitew in Calgary was a study of the proteins bound to protamine mRNA that formed messenger ribonucleoprotein particles. My planned project as a new independent investigator and Assistant Professor at Queen’s University (Kingston, ON) in 1977 was an examination of messenger ribonucleoprotein particles in developing muscle. But a friendship formed at UBC with one of GHD’s graduate students, Choy-Leung Hew, changed all that. Choy had worked with Gordon on haptoglobins and was an expert in protein chemistry. He joined the faculty at Memorial University of Newfoundland in 1974, and soon after developed an interest in the recently discovered antifreeze proteins (AFPs) of marine fishes.  Choy recruited me to the study of AFPs to assist with the molecular biology aspects because I had gained experience in mRNA isolation, cDNA synthesis, and nucleic acid sequencing from my research with GHD in Calgary. It was a fortuitous transition as AFPs have been an extremely productive field for investigating protein structure-function relationships. However, some of the most fascinating insights about antifreeze proteins are those that relate to protein evolution - the theme of the review article GHD wrote over 50 years ago that is echoed here. Our review on protein evolution features examples from the field of antifreeze proteins, but with some parallels to protamines.