Showing posts from May, 2016

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 ethyle…

Ethylene Biosynthesis Pathway: Part 03

Writing is an addiction for me like drinking alcoholic beverage. Once I start it, don't know how to resist myself. When holidays and writing go along, it's really crazy. Particular, the story of Ethylene is so intriguing, I can't help myself to take a holiday nap or watch a movie before finishing biosynthesis pathway part. 
In previous post of ethylene series, we came upto SAM of ethylene biosynthetic pathway. Is there any other metabolic intermediates between SAM and ethylene? Let's explore this question in the following part of the post. 
From several studies scientists came to know that there is no ethylene production in anaerobic condition (absence of oxygen). But, they could detect the degraded product from SAM except ethylene. It gave them an idea that probbably there is another metabolic intermediate intermediate between SAM and ethylene. In this case, Adams and Yang did a very clever experiment. They observed that after anaerobic condition, if they put the reacti…

Ethylene Biosynthesis Pathway: Part 02

According to last post, we came to know that how methionine was discovered as persursor for ethylene biosynthesis. The very next question was whether it is a single step biosynthetic process or multiple steps. In case of multiple steps, there are metabolic intermediates. On that time scientists had two clues to decipher metabolic intermediates. Conversion from methionine to ethylene requires oxygen and inhibited by DNP (2,4-dinitrophenol). DNP is known for uncoupling oxidative phosphorylation. For instance, "phosphorylation" of Adenosine Diphosphate (ADP) by ATP synthase gets disconnected or "uncoupled" from oxidation. So, when they thought about immediate product from methionine where ATP synthase (converts ADP to ATP) is required, the possible one is S-adenosyl methionine (SAM). The conversion step from methionine to SAM requires energy in the form of ATP. So, when DNP blocks that ATP synthesis process, there is no SAM and consequently no ethyle production. 

In 19…