Androgen sensor (AR + CRISPRa)

Detects androgens (testosterone and anabolic-steroid mimics) in water and sport/clinical samples using the human androgen receptor expressed in GRAS yeast — a eukaryotic sensing class bacteria cannot do — gating a CRISPRa circuit driving a fluorescent reporter.

Chemical / metaboliteBSL-1 chassisGRAStemplateandrogentestosteroneEDCendocrine-disruptorwaterchemicaleukaryoticyeastCRISPRa

Open in designer Design guide RNA

Input

Androgens (testosterone / mimics)

Chemical / metabolite

→

Sense

CRISPRa-activation

dCas9-VPR (eukaryotic CRISPRa activator)

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Chassis

Saccharomyces cerevisiae (BY4741)

BSL-1

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Output

yEGFP

fluorescent

What it detects

Analyte: Androgens (testosterone / mimics) — Yeast androgen screen detects sub-nM to nM DHT/testosterone
Category: Chemical / metabolite
Signal: Androgenic activity in water, clinical, or anti-doping samples

Genetic circuit

⤢ click to enlarge

Genetic construct (SBOL)

The DNA construct as transcription units, drawn with SBOL Visual part glyphs.

⤢ click to enlarge

CRISPR sensing mechanism

Strategy: CRISPRa-activation · amplifier logic
Cas protein: dCas9-VPR (eukaryotic CRISPRa activator)
Analyte sensor: Ligand-bound human androgen receptor (AR) binds androgen-response elements (AREs), activating an ARE promoter (the yeast androgen screen).

Signal flow

Androgen -> AR binds ARE promoter -> sgRNA -> dCas9-VPR amplifies the reporter (CRISPRa) -> fluorescence rises with androgenic activity.

Safe chassis

Saccharomyces cerevisiae (BY4741) — Saccharomyces cerevisiae

GRAS baker's yeast — the model eukaryote. Being a eukaryote, it can host human nuclear receptors and GPCRs, unlocking sensing of steroids, hormones, and other eukaryotic-specific ligands that bacteria cannot detect. dCas9 CRISPRi/CRISPRa are well established.

BSL-1GRAS · FDA GRAS

Genetic parts

Part	Role	Source / id
Human androgen receptor (AR)	regulator	Human AR; Sohoni & Sumpter 1998 (yeast androgen screen)
ARE promoter	promoter	androgen-response-element yeast promoter
sgRNA	sgRNA	designed against / upstream of the reporter promoter
sgRNA scaffold (SpCas9) GTTTTAGAGCTAGAAATAGCAAGTTAAAATAAGGCTAGTCCGTTATCAACTTGAAAAAGTGGCACCGAGTCGGTGC	sgRNA	Standard SpCas9 scaffold
dCas9-VPR	dCas9	Yeast CRISPRa (dCas9-VPR)
yEGFP	reporter	yeast-enhanced GFP

Output & readout

Type: fluorescent
Reporter: yEGFP
Readout: Green fluorescence (plate reader)
Positive result: Fluorescence increases with androgenic activity.

Performance

Device validated: No — design template (parts validated individually)

The yeast androgen screen (AR/ARE) is a validated assay; the CRISPRa-amplified version is a design template. Reports total androgenic activity, useful for unknown mixtures.

Safety

Biosafety level: BSL-1 (non-pathogenic chassis)
GRAS chassis: Yes
Biocontainment: Auxotrophic markers; GRAS yeast host.
Field-deployable: Yes (with containment)

GRAS baker's yeast; eukaryotic chassis enables human-receptor sensing.

Build & run

#	Stage	Step
1	design	Design sgRNA Target/position the sgRNA; check S. cerevisiae off-targets.
2	assembly	Assemble units Sensor -> sgRNA; dCas9; reporter. Use the host's standard toolkit.
3	transformation	Transform S. cerevisiae Transform, select, and confirm low background.
4	induction	Expose to sample Incubate with the sample plus a androgen standard curve.
5	readout	Read result Relate signal to concentration.

Source & parts

Design

Design template combining the yeast androgen screen (AR/ARE) with eukaryotic CRISPRa

Parts validated in

Sohoni & Sumpter 1998 (yeast androgen screen)
Yeast dCas9-VPR CRISPRa

License

Parts per their original sources; design template CC BY 4.0