Figure 2
Strategy for constructing DNA cassettes expressing different PhaC2 Ps s for PHA production. Five vectors containing different DNA cassettes of mutated phaC2 Ps under the control of a lac promoter were constructed. Genes phaC2 Ps QK and phaC2 Ps QKST are site-specific mutants of phaC2 Ps using the original codon strategy, and phaC2 Ps O is the gene coding for PhaC2PsQKST yet with its codon optimized (the selected codon for each amino acid and the percentage of this codon in the original coding sequence are listed on the right). In the fifth DNA cassette, DNA sequence coding for a hairpin structure [29] was inserted into the 5’ untranslated region of the gene. Double underlinines indicate the ribosome binding sites (RBS), and the single underlinine indicates translation start codon. Abbreviations: bla: beta-lactam resistance gene, phbA: β-ketothiolase gene, phbB: acetoacetyl-CoA reductase gene, phaC2 Ps : a PHA synthase gene from P. stutzeri 1317.