Insights from computational analysis of full-length β-ketoacyl-[ACP] synthase-II cDNA isolated from American and African oil palms

Abstract

Background:Palm oil derived from fruits (mesocarp) of African oil palm (Elaeis guineensis Jacq. Tenera) and American oil palm (E. oleifera) is important for food industry. Due to high yield, Elaeis guineensis (Tenera) is cultivated on commercial scale, though its oil contains high (~54%) level of saturated fatty acids. The rate-limiting activity of beta-ketoacyl-[ACP] synthase-II (KAS-II) is considered mainly responsible for the high (44%) level of palmitic acid (C16:0) in the oil obtained from E. guineensis.Objective:The objective of this study was to annotate KAS-II cDNA isolated from American and African oil palms.Materials and Methods:The full-length E. oleifera KAS-II (EoKAS-II) cDNA clone was isolated using random method of gene isolation. Whereas, the E. guineensis KAS-II (EgTKAS-II) cDNA was isolated using reverse transcriptase polymerase chain reaction (RT-PCR) technique; and missing ends were obtained by employing 5’and 3’ RACE technique.Results:The results show that EoKAS-II and EgTKAS-II open reading frames (ORFs) are of 1689 and 1721 bp in length, respectively. Further analysis of the both EoKAS-II and EgTKAS-II predicted protein illustrates that they contains conserved domains for ‘KAS-I and II’, ‘elongating’ condensing enzymes, ‘condensing enzymes super-family’, and ‘3-oxoacyl-[ACP] synthase II’. The predicted protein sequences shows 95% similarity with each other. Consecutively, the three active sites (Cys, His, and His) were identified in both proteins. However, difference in positions of two active Histidine (His) residues was noticed.Conclusion:These insights may serve as the foundation in understanding the variable activity of KAS-II in American and African oil palms; and cDNA clones could be useful in the genetic engineering of oil palms.

Three-dimensional (3D) structure prediction of the American and African oil-palms β-ketoacyl-[ACP] synthase-II protein by comparative modelling

“…The EgKASII protein (sequence) is known to have a high (95%) similarity with the EoKASII protein [2]. However, secondary structure analyses of both proteins suggest that both proteins have the same number of alpha helices, coils and beta strands.…”

“…The nucleotide database of NCBI contains full-length KASII cDNA sequences for both EgKASII and EoKASII [Gene Bank Accession Numbers: AF220453 (EgKASII) and FJ940767 (EoKASII)] [ 2 ]. The deduced amino acid sequence for EgKASII and EoKASII proteins are available in protein database of NCBI.…”

“…Palm-oil obtained from the African oil-palm fruitmesocarp- tissue do contain about 53% saturated fatty acids, and palmitic acid (C 16:0 ) content in it is 44% [ 1 ]. A high level of saturated fatty acids in our diet is considered as unhealthy [ 2 ]. However, palm-oil obtained from the American oil-palm fruitmesocarp- tissue contains about 28% of saturated fatty acids, and only about 25% of C 16:0 [ 3 , 4 ].…”

“…The understanding of KASII in the African and American oilpalms is important in order to understand the deviation in its activity in two oil palm species. As a part of it, the full length KASII cDNA clones were isolated from both E. guineensis ( EgKASII ) and E. oleifera ( EoKASII ) previously [ 2 ]. The EgKASII and EoKASII cDNAs are 2011 and 2138 base pair in length [ 2 ].…”

“…As a part of it, the full length KASII cDNA clones were isolated from both E. guineensis ( EgKASII ) and E. oleifera ( EoKASII ) previously [ 2 ]. The EgKASII and EoKASII cDNAs are 2011 and 2138 base pair in length [ 2 ].…”