Component Introduction

FnBPA

Fibronectin-Binding Proteins (FnBPs), originating from Staphylococcus aureus, are pivotal mediators of bacterial entry into non-professional phagocytic cells through integrin-mediated internalization. In this pathway, FnBPs on the bacterial surface first bind extracellular fibronectin (Fn), which then bridges to α₅β₁ integrins on the host cell membrane, forming a high-affinity complex. The assembly of this FnBPs-Fn-Integrin bridge promotes local integrin clustering and the subsequent remodeling of the actin cytoskeleton, facilitating progressive membrane extension and bacterial engulfment, ultimately leading to vesicular internalization. Notably, once internalized, S. aureus actively modulates endosomal trafficking to avoid lysosomal fusion and degradation, thereby ensuring sustained intracellular persistence.

Hypoxia-Repomsive Module (HRM)

This system consists of a canonical two-component module (nreB and nreC) together with a nitrate receptor gene (nreA). NreB is an oxygen-sensing histidine kinase, and NreC is its cognate response regulator. Under hypoxia, NreB undergoes autophosphorylation and subsequently transfers the phosphoryl group to NreC. The phosphorylated form of NreC (NreC-P) binds to the promoter region of the downstream narT gene, thereby initiating partial activation of transcription. In the presence of nitrate, the nitrate-binding protein NreA potentiates this response, driving maximal activation of P_narT. Thus, P_narT integrates oxygen (via NreB/NreC) and nitrate (via NreA) inputs.

Parts in Registry

This section summarizes all the components involved in the project, including their names, identifiers, categories, and brief descriptions. In addition, if you would like to learn more about their functions and performance, you may refer to our Design and Result pages, which might be helpful.

In the legend of the Trojan Horse, Odysseus planned the Trojan horse scheme and hid the Trojan horse to lead the Greek army. Sinon persuaded the Trojans to bring the wooden horse into the city with lies, thus enabling the Greek army to capture Troy. The combination of strategy and persuasion transformed cunning into victory.

Drawing the inspiration from the wisdom of the Ancients, we designed the Sinon series (α, β, γ, δ) for invasion, which is similar to Sinon and the Odysseus series (α, β) for a set of plasmids providing graded expression and invasion capabilities integrating mythological analogies with molecular design.

Sinon α (BBa_25YCCP79) and Sinon β (BBa_25DUJ6XZ) are used for expression in Staphylococcus， which respectively activated by two promoters of different intensities for the expression of invasive protein fnbp and fluorescent protein sfGFP.

Similarly, in Sinon γ (BBa_25YJ73ZN) and Sinon δ (BBa_25M7ZJLU), a promoter of Escherichia coli was used to perform different expression intensities of selected proteins in the engineered Escherichia coli JM110.

Just as Sinon’s words persuaded the Trojans to let the horse inside their walls, the Sinon plasmids “convince” host cells to internalize engineered bacteria, changing random intrusions to programmed invasions.

The Odysseus series (α and β) follows a design rational inspired by Odysseus’s strategy: these constructs sense low-oxygen conditions via a hypoxia-responsive module (nreABC–P_narT) to selectively express Apoptin, “attacking” only in the target microenvironment. Odysseus α series (BBa_25M0SVWF) operates in S. epidermidis and Odysseus β (BBa_25KMWD0P) series operates in S. xylosus, translating environmental signal into precise and context-specific genetic action.

In the spirit of Odysseus‘s strategy, the Odysseus series is designed to remain inactive under normoxic conditions and to initiate function only when hypoxia is detected, converting an ancient symbol of tactical deception into a precise biological control system.

Our design is bold and decisive, analogous to Odysseus’s strategic planning. However, the details are extremely precise - this reflects Sinon’s ingenious and precise language art.

Composite Parts and Plasmids

Basic Parts

Bacterial Strains

The sequences of sfgfp, fnbp, ermC, and apoptin were all codon-optimized for Staphylococcus.

There are two variants of P_narT, derived respectively from the genomes of Staphylococcus xylosus ATCC 29971 and Staphylococcus epidermidis ATCC 14990, which were used in constructing hypoxia-responsive expression plasmids for these two strains.