Journal of Proteomics & Bioinformatics
Open Access
ISSN: 0974-276X
+44 1223 790975
ISSN: 0974-276X
+44 1223 790975
Research Article - (2009) Volume 2, Issue 7
Enzymes of Type III polyketide synthase superfamily play an important role in the biosynthesis of medicinal natural products in plants. The PKSs generate the diversity of polyketide derivatives by changing their preference for starter molecules, the number of acetyl additions catalysed and the cyclisation of the polyketide intermediates. The amazing structural features of gingerol and related compounds of ginger (Zingiber officinale Rosc., Zingiberaceae) provide a genomic insight in to the presence of novel forms of PKS. The current study describes the isolation and characterisation of a novel of PKS from Z. officinale using degenerate oligonucleotide based PCR method. The inducible expression of recombinant ZoPKS in E. coli resulted in the formation of a protein with approximate molecular weight of 43kD. The comparative sequence and phylogenetic analysis of ZoPKS shows its significant variation from already identified PKSs. The novelty of the ZoPKS was further confirmed by homology modeling based comparative structural bioinformatics analysis. The novel form of PKS identified in the study has very remarkable amino acid substitutions at the key residues determining the starter substrate selectivity and condensation reactions and forms a genomic basis of PKS from Z. officinale to explore its potential in biosynthesis of gingerol and related compounds.
The amazing diversity of polyketide derivatives in plants is generated by a group of structurally related enzymes called as the type III polyketide synthases (PKSs). The most well known and widely distributed member of the PKS superfamily is the chalcone synthase(Winkel-Shirley, 2001). In the typical reaction mechanism, it forms the chalcone by the stepwise decarboxylative condensation of coumaroyl CoA with three malonyl coA followed by the claisen type cyclisation of the tetraketide product (Jez et al., 2001). Extensive gene duplication followed by the functional divergence is believed to have played an important role in generating the biochemical diversity of PKS superfamily. The expanding members of the family, as shown by the identification of 2-pyrone synthase, stilbene synthase, benzalacetone synthase, valerophenone synthase, acridon synthase etc., from various sources indicate that the biosynthetic potential of the PKS is just begin to be explored and many more members are to be identified from plants especially from medicinal plants (Austin and Noel, 2003).
Zingiber officinale Rosc. (ginger, Zingiberaceae) is well known for its use in traditional therapeutic and preventive medicine. The major pharmacologically active component present in Z. officinale is of the gingerol group (Ramirez- Ahumada Mdel et al., 2006). Molecular insight in to the gingerol biosynthesis suggested that enzymes similar to type III polyketide synthases are having important role (Denniff et al., 1980; Schröder, 1997). Considering the pharmacological potential of gingerol and the distribution of structurally similar compounds in other members of the family, identification and characterisation of the PKS from Z. officinale can provide a genomic basis for elucidation of biosynthetic pathway. In the present work, we are reporting the cloning and characterisation of a novel form of type III PKS fromZ. officinale. The comparative structural bioinformatic analysis suggests that the PKS identified in the study may be a prime candidate for the biosynthesis of phenylbutanone derivatives of Z. officinale.