Each gene expression vector was constructed by standard DNA manipulation including several cycles of fragment-primed PCR. Using genomic DNA and cDNA as a template, three DNA fragments (TAL, Sam5, and COMT) were PCR-amplified with appropriate pairs of primers (Table 1) and cloned into pCR^®-TOPO, resulting in pCR-Tal, pCR-Sam5, and pCR-Com, respectively. To construct the pET expression plasmids under the control of the T7 promoter, the BglII-HindIII fragment was excised from pCR-Tal and cloned between the BamHI and HindIII sites of pET-28a(+), resulting in pET-TAL (Fig. 2). The NdeI-HindIII fragment was excised from pCR-Sam5 and cloned between the NdeI and HindIII sites of pET-28a(+), resulting in pET-Sam5 (Fig. 2). The NdeI-HindIII fragment was excised from pCR-Com and cloned between the NdeI and HindIII sites of pET-28a(+), resulting in pET-COM (Fig. 2). To construct an expression vector containing the three genes that were each under the control of the T7 promoter, we first amplified the 1.76-kb DNA fragment containing the TAL coding region using pET-TAL as a template with primer TAL-N and CPac (the sequence is located downstream of the T7 terminator region of the pET vector and contains the designed PacI site; Table 1). Using the pET-Sam5 as a template, the 2.54-kb DNA fragment containing the Sam5 coding region was PCR-amplified with primer NPac (the sequence was located upstream of the T7 promoter region of the pET vector and contained the designed PacI site; Table 1) and CPac. In addition, the 1.88-kb DNA fragment containing the COMT coding region was PCR-amplified using pET-COM as a template with primer NPac and COM-R. The amplified fragments were digested with each restriction enzymes and cloned between BamHI- and HindIII-digested pET-28a(+) by a four-fragment ligation, resulting in pET-T5 M (Fig. 2). The right direction of Sam5 fragment in pET-T5 M was confirmed by restriction mapping. The gap between the previous terminator and the next promoter (TAL-Sam5 and Sam5-COM) was 696 bp. The pET-T5 M plasmid was orderly constructed, and contained the three genes with their own T7 promoter, ribosome-binding site (RBS), and terminator sequence.