2.2 Plasmid construction
The genes encoding H protein and LplA protein were amplified fromE. coli MG1655 cells by PCR with His-tag and cloned into the pET28a+ vector, yielding the plasmids pET28-H and pET28-LplA, respectively. The lysine residue at position 64 of the H protein for binding lipoic acid was mutated into alanine, resulting in the plasmid pET28-HK64A. The plasmids were transferred into competent cells of E. coli BL21(DE3) for protein expression. Oligonucleotide sequences of primers used for the cloning of genes coding for the target proteins were given in Table 1.