Chemical synthesis of a structure gene coding for small subunit of ribulose‐1,5‐bisphosphate carboxylase/oxygenase from tobacco

A structural gene with 385 bp, which codes for the mature small subunit (rbcS) of ribulose‐1,5‐bisphosphate carboxylase/oxygenase from tobacco, has been redesigned according to the codon usage of E.coli and chemically synthesized. To facilitate the systematic investigation of structure‐functional relationship of the rbcS by site‐specific mutagenesis, twenty one unique restriction sites distributed throughout the synthetic gene were designed. Gene synthesis was started from chemically synthesizing sixteen oligonucleotides each with 23–66 nucleotides, and these oligonucleotides were annealed to form eight duplexes from which 5'‐ and 3'‐ two half molecules were formed by stepwise T₄ DNA ligase reaction, and then each half molecule was cloned into plasmid pWR13, after that, two half molecules were further confirmed by DNA sequencing, finally both half molecules excised from the cloning plasmid were recombinated to form plasmid pCOTrbcS containing the whole structural gene for tobacco rbcS.