Memory of Tony Bleecker
As a part of ethylene series, it's obvious to mention unique and seminal discoveries of Tony Bleecker about ethylene phenotypic assay, discovery of ethylene receptor and its function, and more elaborately to advance our understading about ethylene perception. His key discoveries brought a new paradigm in textbook level. He passed away January, 2005 due to cancer.
In the main ethylene series, I'll discuss about his work and background stories with references. Here, I would like to summarize his major contributions in summary.
- Tony Bleecker started his PhD in 1982 and during that time the ethylene biosynthetic pathway was known, although none of enzymes from biosynthetic pathway were isolated. During his PhD, he isolated ACC synthase from tomato and it was a great piece of starting work on ethylene from him. (Bleecker et al. 1986)
- His ground breaking discovery came when he started working on model plant Arabidopsis thaliana. He isolated a dominant mutant (etr1-1) which is ethylene insensitive. This work found its place on the cover of Science. This is the single most important paper in ethylene field so far. (Bleecker et al. 1988)
- He continued his work on etr1-1 mutant and identified the gene. They reported that ETR1 encoded a histidine kinase like molecule flanked on the N-terminus by three alpha helices predicted to span a membrane and on the other end by a response regulator domain. From this result it was clear that ETR1 has similarity with bacterial two component system and they predicted it as ethylene receptor. (Chang et al. 1993)
- The most enigmatic part to prove ETR1 as a receptor was to show the binding of ethylene with ETR1. Ethylene is a gas and how it is binding with a polypeptide. They expressed ETR1 in yeast and showed that it not only works as receptor for ethylene, but more precisely amino terminal hydriphobic domain is the binding site for ethylene. (Schaller et al. 1995)
- The convincing chemical explanation for binding between ethylene gas and polypeptide was elusive. They have showed that cooper atom coordinated by Cys residues on the membrane spanning domain facilitates the binding of ethylene gas. (Rodriguez et al. 1999)
Tony Bleecker will remain in our heart for his key discoveries and contributions for understanding about ethylene. His papers will be cited to show respect to his work.