Molecular characterization, expression profiling and function analysis of pyruvate decarboxylase gene from Salvia miltiorrhiza Bge. f. alba

Pyruvate decarboxylase (PDC, EC 4.1.1.1) is the key enzyme for all homo-fermentative ethanol pathways, and catalyzes the nonoxidative decarboxylation of pyruvate to acetaldehyde. The present study describes the cloning and characterization of a cDNA encoding pyruvate decarboxylase from Salvia miltiorrhiza 8ge. f. alba (designated as SmPDC, Gen8ank Accession No. JF775376). Comparative and bioinformatic analyses revealed that SmPDC showed extensive homology with PDCs from other plant species. Phylogenetic tree analysis indicates that SmPDC belongs to the plant PDC superfamily and has the closest relationship with PDC from Lycoris aurea. Tissue expression pattern analysis revealed that SmPDC expressed strongly in roots, followed by leaves and stems, implying that SmPDC was a constitutively expressed gene. Moreover, the expression of SmPDC significantly induced by flooding stress. The purified recombinant SmPDC had specific activity of 66U, mg protein⁻¹. The Km of the recombinant SmPDC was 1.6 mM. Color complementation assay confirmed that SmPDC played an important role in anaerobic respiration pathway and encoded a functional protein. The characterization, expression profile and functional analysis of SmPDC gene will be helpful for further studies concerning the role of SmPDC in anaerobic respiration pathway and metabolic engineering against anaerobic stress in S. miltiorrhiza Bge. f.alba.