Introduction

How do we achieve perming and dyeing through synthetic biology methods?

Engineered yeast producing natural pigments and short peptides with abundant sulfhydryl was designed. A xylose responding system was also created to made the pigment fade and turn the curled hair straight, resuming the hair to its original state.

Perm

The key in perming lies in re-conformation of disulfide bonds, and pepACS is used to reform the disulfide bonds between fibers within the cortex when the hair is bent by external forces. DsbC is used to straighten the hair following the same principal.

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design1

PERM: Various reagents used in traditional perming, such as mercaptoacetic acid, hydrogenperoxide and P-phenylpropanediamine are allergic and carcinogenic in addition to causing serious damage to hair. In order to minimize the damage to health and hair during perming process, short peptides with abundant sulfhydryl were chosen as the reductant[1]. Three short peptides selected based on modeling result, including PepA, PepB and SPB, were connected with Rigid Linker (PepACS). The rigid linker is more prone to form α-helix, which can separate sulfhydryl preventing them from reacting with each other. The complex is small enough to enter the cortex through the cuticle and form dislocated disulfide bonds with α-keratins, which can change the shape of hair.

The rigid linker is more prone to form α-helix, which can separate sulfhydryl preventing them from reacting with each other. The complex is small enough to enter the cortex through the cuticle and form dislocated disulfide bonds with α-keratins, which can change the shape of hair.

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UNDO: Disulfide isomerase has been proven to help open up cuticle and give short peptides easier access into the cortex[2]. Connecting disulfide isomerase and short peptides with GS-linker (DsbC) can therefore allow more short peptides to enter cuticle. When DsbC is applied on hair fixed by external forces, it forms more disulfide bonds without unpaired sulfhydryl thereby straightening the hair.

Dye

BLUE: Indigo

DYE: We chose indigo as dye for blue. Indole is oxidized by FMO into leucoindigo[3]. It is reduced to leucoindigo by ethanol and lactic acid produced by Pichia pastoris, which can better adhere to hair. Leucoindigo is then oxidized by oxygen into indigo to turn the hair blue.

UNDO: Laccase can oxidize indigo into colorless substances[4].

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Design3

Indigo is one of the oldest dyes applied in textile dyeing [7], and we explored its efficacy in hair dyeing in our project.

Indole, the pigment precursor, is oxidized by flavin containing monooxygenase (FMO) into indigo. It is then reduced to leucoindigo since indigo can only adhere to the surface of hair due to its poor water solubility. Compared to indigo, leucoindigo has fine water solubility therefore it can enter the cortex providing better sustainability of hair color, which, after being oxidized into indigo, would endow the hair with blue.

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YELLOW: Curcumin

DYE: Curcumin was chosen as the dye for yellow. The ferulic acid is catalyzed into curcumin with the aid of 4CL, ACC and CUS.

UNDO: Curcumin reductase(curA) can reduce curcumin to colorless tetrahydrocurcumin[9].

RED: Lycopene

DYE: Lycopene was opted for red dye. FPP can be synthesized into lycopene by crtE, crtB and crtI[6].

UNDO: LOX2 can oxidize lycopene and make it fade.

Choice of chassis organism

We chose pichia pastoris as our chassis organism because it possesses multiple advantages other protein expression systems don't. Featuring inducible strong promoters, high expression, high stability, high biological activity of expression product, P. pastoris has another advantage that exogenous genes can be integrated into chromosomes. Moreover, it eliminates our safety concerns. Yeast is classified as biosafety level 1 organism, which poses little threat to human and the environment, and we chose the histidine defect type of pichia pastoris which can't survive outside a certain culture media.

Xylose Responding System

Mr. Tony project not only can achieve perm and dyeing, but also has the function of resuming the hair to its original state, realized by the xylose responding system in which the xylose induced promoter and genes of corresponding enzymes are introduced.

Hardware

We designed a small fermenter and used the filter membrane to separate the product from the yeast for safe use.

In addition, a hair dyeing comb was designed for applying hair dye cream in real life scenarios. (Please refer to hardware for detailed information)

The design of pathways is truly intriguing, right?! But will it work? If you share the same confusion with me, let's take a look at the proof of concept-

References

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