Isolation and Comprehensive in Silico Characterisation of a New 3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase 4 (HMGR4) Gene Promoter from Salvia miltiorrhiza: Comparative Analyses of Plant HMGR Promoters

Abstract

Salvia miltiorrhiza synthesises tanshinones with multidirectional therapeutic effects. These compounds have a complex biosynthetic pathway, whose first rate limiting enzyme is 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR). In the present study, a new 1646 bp fragment of the S. miltiorrhiza HMGR4 gene consisting of a promoter, 5′ untranslated region and part of a coding sequence was isolated and characterised in silico using bioinformatics tools. The results indicate the presence of a TATA box, tandem repeat and pyrimidine-rich sequence, and the absence of CpG islands. The sequence was rich in motifs recognised by specific transcription factors sensitive mainly to light, salicylic acid, bacterial infection and auxins; it also demonstrated many binding sites for microRNAs. Moreover, our results suggest that HMGR4 expression is possibly regulated during flowering, embryogenesis, organogenesis and the circadian rhythm. The obtained data were verified by comparison with microarray co-expression results obtained for Arabidopsis thaliana. Alignment of the isolated HMGR4 sequence with other plant HMGRs indicated the presence of many common binding sites for transcription factors, including conserved ones. Our findings provide valuable information for understanding the mechanisms that direct transcription of the S. miltiorrhiza HMGR4 gene.

HMGR and CHS gene cloning, characterizations and tissue-specific expressions in Polygala tenuifolia Willd

“…Using Arabidopsis thaliana HMGR (ID: 7ULI in RCSB PDB) and Medicago sativa CHS (ID: 1I86 in RCSB PDB) as templates, the tertiary structures of PtHMGR and PtCHS were modeled by SWISS-MODEL software. The results (Figs [22][23][24] showed that the main structures of PtHMGR and PtCHS were α-helices, β-turns, and random-coils, and the directions from the N-terminus to the C-terminus are shown in red, orange, yellow, green, cyan, blue, and purple, respectively. 390 amino acids of PtHMGR were highly similarity with to template 7ULI, which had a coverage rate of 92.0%.…”

“…Its expression level affects the accumulation of saponins in P. tenuifolia. To date, the HMGR genes in many plants have been successfully isolated and cloned, such as Alisma orientale [18], Bunium persicum [19], Cucumis melo [20], Lithospermum erythrorhizon [21], Catharanthus roseus [22], Salvia miltiorrhiza [23] and etc. However, the involvement of HMGR in the terpenoid biosynthetic pathway has not yet been identified in P. tenuifolia.…”