Cloning and expression analysis of C4H gene from Lepidium apetalum / 药学学报

ABSTRACT

Lepidium apetalum was used as an experimental material in this study. By analyzing the tran-scriptome data of L. apetalum and application of the specific primers, cDNA of cinnamate-4-hydroxylase (C4H) gene was isolated from L. apetalum and named as LaC4H (GenBank accession No. KX064050). Meanwhile, the bioinformatic analysis, prokaryotic expression, purification, tissue-specific expression analysis and expres-sion analysis after methyl jasmonate (MeJA) treatment were carried out. The results indicated that ① The open reading frame (ORF) of LaC4H was 1 518 bp, which encoded a protein of 505 amino acid residues, with a predicted molecular mass of 57.73 kD. ② Bioinformatic analysis showed that LaC4H protein contained the conserved sequences of cytochrome P450 (CYP450) and 5 substrate recognition sites (SRSs) of CYP73A1, therefore LaC4H protein was a member of CYP450 superfamily. The phylogenetic analysis indicated that LaC4H protein showed the highest homology with C4H protein from cruciferous plants (such as AtC4H from Arabidopsis thaliana). ③ Through the construction of the prokaryotic expression vector pET-32a-LaC4H, the recombinant LaC4H protein was successfully expressed in E. coli BL21 (DE3) cells and the recombinant LaC4H protein was purified by Ni2+ affinity chromatography. ④ Real-time PCR analysis indicated that LaC4H was expressed in a high transcript level in stems, lower levels in leaves and flowers, the lowest level in roots. After MeJA treatment, the expression level of LaC4H in leaves was increased significantly to reach the highest level at 48 h. Furthermore, the expression levels of LaC4H were positively correlated with the flavonoids contents in leaves. The results of this study provide the fundamental information on LaC4H gene in the flavonoids biosyn-thesis pathway of L. apetalum.