Re: [DIYbio] Re: Student group needs help genetically modifying foods.

> Instead of Vitamin C or E, you could focus on Vitamin A (aka
beta-carotene)
> instead. The same Johns Hopkins team also made a 3-gene plasmid for
Vitamin
> A biosynthesis, and demonstrated that it worked in yeast (and baked a
bread
> with it!):

Boom: Much more important, considering the relative prevalence of Vit
A/C deficiencies. And, while everyone bleats about Golden Rice, "pirate
yeast" could be rapidly passed hand-to-hand by people in need to make
vitamin enriched breads/biscuits/beers.

Bonus feature; in either case, the vitamin is probably secreted or
otherwise not retained within the cell..? And "naked" vitamin C has a
very short half-life in our oxygen-rich environment. I think Vit A has a
better lifespan.

Downside: Vit A can be overdosed on, whereas Vit C effectively can't.

I'd put money towards a Vit.A yeast if anyone's planning to replicate
the Hopkins team work, assuming you can't just get the plasmid on
request! :)

On 11/02/14 00:39, Patrik D'haeseleer wrote:
> For something as simple as Vitamin C biosynthesis in yeast, chances are
> someone has already tried this. In this case, a simple google search led to
> this paper:
>
> Biosynthesis of Vitamin C by Yeast Leads to Increased Stress Resistance<http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0001092>
>
> in which they show that you only need three genes to produce L-ascorbic
> acid (vitamin C) in yeast, although they eventually added two more to avoid
> a bottleneck in the tail end of the pathway.
>
> Engineering five genes into yeast from scratch is still beyond what can be
> done with a highschool team (and Vitamin E looks even harder). Luckily for
> you, the 2011 Johns Hopkins iGEM team already made a plasmid with the three
> key enzymes, although I'm not sure they got it to work:
>
> http://2011.igem.org/Team:Johns_Hopkins/Project/VitC
>
> Instead of Vitamin C or E, you could focus on Vitamin A (aka beta-carotene)
> instead. The same Johns Hopkins team also made a 3-gene plasmid for Vitamin
> A biosynthesis, and demonstrated that it worked in yeast (and baked a bread
> with it!):
>
> http://2011.igem.org/Team:Johns_Hopkins/Project/VitA
> http://2011.igem.org/Team:Johns_Hopkins/Vit/Results
>
> You (or one of your teachers) may be able to get the plasmid from this
> group. At that point, it would simply be a matter of transforming it into
> yeast, and testing it out - something that should be well within reach of a
> high school team. If you get that done, you can thenn modify the pathway
> further to produce any of a range of other brightly colored carotenoids,
> such as zeaxanthin or canthaxanthin.
>
> Patrik
>

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