Use a pbad promoter(K206000),strong RBS(B0034),Bxb1 coding region(K907000),and a double terminator(B0015).Will generate Bxb1 recombinase when pbad begin to express.
Notes
This is a composite part including Bxb1 protein coding region encoded in part BBa_K907000.
Source
All of these parts are from Kit Plate of iGEM foundation.