Completion of the cytosolic post-chorismate phenylalanine biosynthetic pathway in plants

in steemstem •  16 days ago

This will likely be my last scientific publication after a 45 year career in plant biology/biochemistry:

Yichun Qian, Joseph H. Lynch, Longyun Guo, David Rhodes, John A. Morgan & Natalia Dudareva. Completion of the cytosolic post-chorismate phenylalanine biosynthetic pathway in plants. Nature Communications volume 10, Article number: 15 (2019)

Abstract. In addition to being a vital component of proteins, phenylalanine is also a precursor of numerous aromatic primary and secondary metabolites with broad physiological functions. In plants phenylalanine is synthesized predominantly via the arogenate pathway in plastids. Here, we describe the structure, molecular players and subcellular localization of a microbial-like phenylpyruvate pathway for phenylalanine biosynthesis in plants. Using a reverse genetic approach and metabolic flux analysis, we provide evidence that the cytosolic chorismate mutase is responsible for directing carbon flux towards cytosolic phenylalanine production via the phenylpyruvate pathway. We also show that an alternative transcription start site of a known plastidial enzyme produces a functional cytosolic prephenate dehydratase that catalyzes the conversion of prephenate to phenylpyruvate, the intermediate step between chorismate mutase and phenylpyruvate aminotransferase. Thus, our results complete elucidation of phenylalanine biosynthesis via phenylpyruvate in plants, showing that this pathway splits from the known plastidial arogenate pathway at chorismate, instead of prephenate as previously thought, and the complete pathway is localized in the cytosol.

41467_2018_7969_Fig1_HTML.png
Proposed plant phenylalanine biosynthetic pathways. Characterized enzymes and transporters are shown in solid colors. Uncharacterized enzymes and transporters (boxes) are shown in gray or with question marks. ADH arogenate dehydrogenase, ADT arogenate dehydratase, AS anthranilate synthase, pCAT plastidial cationic amino acid transporter, CM chorismate mutase, PDT prephenate dehydratase, PPA-AT prephenate aminotransferase, PPY-AT phenylpyruvate aminotransferase, TAT tyrosine aminotransferase Image Source:

I end my career with >10,000 citations: David Rhodes - Google Scholar. If I were to leave any advice for a young scientist just starting out their career, it would be to collaborate. Today, science is increasingly interdisciplinary, requiring skills from many different fields of specialization. Don't be afraid to team up with experts from different disciplines ... it will broaden your horizons, enhance your vision and be extremely rewarding.

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Ah..this takes me back to my Metabolism class. Memorising the biosynthesis of Phenylalanine, among many others.





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Sir: Please accept my Respects! :)

Very nice last words! Are we by the way allowed to congratulate you for retiring (I know colleagues who are allergic to the word itself)? Do you want to get some emeritus position?

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Sorry for not replying sooner ... I have been traveling, with limited access to internet. Thank you for your retirement congratulations! I am not looking for another emeritus position (currently I am emeritus at Purdue University).

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Ah ok so you have one! That's the point I missed ^^