Abstract: In order to explore the functional differences between PhzA/B and the effects on the synthesis of PDC and PCA, after comparing, screening and synthesizing the phzA and phzB genes from different bacteria were studied. The result showed that PDC and PCA could be detected in seven mutants, in which heterologous phzB genes replaced the endogenous phzA and phzB gene at the same time. However, PDC could not be detected in the secondary metabolites of five mutants, in which two heterologous phzA genes replaced the endogenous phzA gene and three heterologous phzB genes replaced the endogenous phzB gene, and the simultaneous presence of phzAB wound promote the synthesis of PCA. Moreover, structural analysis showed that there were some differences in some regions of PhzB proteins from different bacteria. The protein structures of PhzA and PhzB were similar, but PhzA lacked the corresponding active amino acid sites of PhzB. In conclusion, PhzA/B proteins from different bacteria had relatively high sequence similarity, but had certain differences in structure and function. They all played an important role in the synthesis of phenazine compounds. Among them, the function of PhzB protein was important to catalyze the synthesis of PDC, while PhzA protein could promote the synthesis of PCA.

Key words: phenazine synthetic protein, phenazine core precursor, metabolic engineering, systems analysis, biosynthesis