Team:PKU Beijing/Project/AND Gate 2 Design

One of the Second AND Gate Design

Primarily we have 2 alternative design of the second AND Gate. One of the them employs the same mechanism as the first AND Gate. However, the activator is not T7 polymerase, it is a different activator with amber mutation of its Ser codon. Actually, we picked two candidates activator proteins. One of them is from partsregistry 2009 distribution, the PhiR73 delta activator and corresponding promoter PO promoter. The other is T3 polymerase and its promoter T3 promoter.

fig1. One design of the second AND Gate

One of the input to the second AND Gate is from the ring signal. Because both of the AND Gates share the ring signal input, SupD tRNA is shared from AND Gate 1. The second AND Gate is intact only when coupled to the first AND Gate. The other input to the second AND Gate, of course, is from the memory module, we put a CI434 repressible and CI inducible promoter upstream of the PhiR73 delta/T3pol (amber mutation)protein.

When the bistable switch is in the “NO MEMORY” state, namely the CI434 state, PhiR73 delta/T3pol (amber mutation) mRNA is not expressed. At this time, ring signal alone, though expresses SupD tRNA, has no effect. When the bistable switch is turned to the “MEMORY” state, with the constitutive expression of CI and the increase of PhiR73 delta/T3pol mRNA level, the ring signal can lead to expression of functional PhiR73 delta/T3pol by rescuing the amber mutation in the PhiR73 delta/T3pol protein.

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