Evolutionary view of acyl-CoA diacylglycerol acyltransferase (DGAT), a key enzyme in neutral lipid biosynthesis

<p>Abstract</p> <p>Background</p> <p>Triacylglycerides (TAGs) are a class of neutral lipids that represent the most important storage form of energy for eukaryotic cells. DGAT (acyl-CoA: diacylglycerol acyltransferase; EC 2.3.1.20) is a transmembrane enzyme that acts in the final and committed step of TAG synthesis, and it has been proposed to be the rate-limiting enzyme in plant storage lipid accumulation. In fact, two different enzymes identified in several eukaryotic species, DGAT1 and DGAT2, are the main enzymes responsible for TAG synthesis. These enzymes do not share high DNA or protein sequence similarities, and it has been suggested that they play non-redundant roles in different tissues and in some species in TAG synthesis. Despite a number of previous studies on the DGAT1 and DGAT2 genes, which have emphasized their importance as potential obesity treatment targets to increase triacylglycerol accumulation, little is known about their evolutionary timeline in eukaryotes. The goal of this study was to examine the evolutionary relationship of the DGAT1 and DGAT2 genes across eukaryotic organisms in order to infer their origin.</p> <p>Results</p> <p>We have conducted a broad survey of fully sequenced genomes, including representatives of Amoebozoa, yeasts, fungi, algae, musses, plants, vertebrate and invertebrate species, for the presence of DGAT1 and DGAT2 gene homologs. We found that the DGAT1 and DGAT2 genes are nearly ubiquitous in eukaryotes and are readily identifiable in all the major eukaryotic groups and genomes examined. Phylogenetic analyses of the DGAT1 and DGAT2 amino acid sequences revealed evolutionary partitioning of the DGAT protein family into two major DGAT1 and DGAT2 clades. Protein secondary structure and hydrophobic-transmembrane analysis also showed differences between these enzymes. The analysis also revealed that the MGAT2 and AWAT genes may have arisen from DGAT2 duplication events.</p> <p>Conclusions</p> <p>In this study, we identified several DGAT1 and DGAT2 homologs in eukaryote taxa. Overall, the data show that DGAT1 and DGAT2 are present in most eukaryotic organisms and belong to two different gene families. The phylogenetic and evolutionary analyses revealed that DGAT1 and DGAT2 evolved separately, with functional convergence, despite their wide molecular and structural divergence.</p

Cloning and characterization of diacylglycerol acyltransferase (DGAT) cDNA sequence from Brassica juncea cv. Pusa Bold

30-36Diacylgycerol acyltransferase (DGAT: EC 2.3.1.20) is the only enzyme in the Kennedy pathway that is exclusively committed to the synthesis of storage oil in plants. In this study, cloning and characterization of DGAT gene sequence from Brassica juncea cv Pusa bold, an important oil seed crop of India is reported. A partial gene sequence of 2003 bp was PCR amplified and cloned from B. juncea. Sequence analysis showed that it has 10 exonic and 9 intronic sequences in the partial gene. Two cDNA sequences namely BjDGAT 1 and BjDGAT 2 (1.5 kb) encoding DGAT enzymes were amplified by RT-PCR from the developing seeds. The complete length of these two cDNAs as determined by RACE technique was 1768 bp, including 5’ and 3’-UTR. Comparative analysis of the sequences showed that BjDGAT1 was 85.1% and 96% identical to BjDGAT2 across 1512 coding region and 503 overlapping deduced amino acids respectively. These proteins were alkaline in nature (pI, 8.5-8.6), having similar molecular size (56-57 kD), an N-terminal hydrophilic segment and 9 transmembrane segments. Diacylglycerol/phorbol ester-binding motif (HKWXXRHXYXP) and acyl CoA binding motif (FYXDWWN) required for binding of substrates remained conserved in these proteins. Expression of the two transcripts of DGAT and their role in oil biosynthesis can further be studied

Identification and quantification of polyphenolic compounds in underutilized fruits (Star fruit and Egg fruit) using HPLC

487-493<span style="font-size:11.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;letter-spacing:-.1pt;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">The study was aimed to investigate the antioxidant capacity, total phenolics, total flavonoids and polyphenolic compounds of two common underutilized fruits namely, star fruit and egg fruit. Results showed that, the star fruit extract had higher total phenolics content (161.56±9.24 mg GAE/100 gm FWB) and DPPH radical scavenging ability (91.77±8.68 mg ascorbic acid equivalent antioxidant activity (AAEAA) /100 gm fresh weight basis (FWB) with low IC50 value = 0.6 mg/ml compared to egg fruit extract which had a low phenolics content (152.45±8.75 mg gallic acid equivalent (GAE) /100 gm FWB) as well as lesser DPPH radical scavenging activity (87.21<span style="font-size:11.0pt; font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-bidi-font-family:mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">±6.32 <span style="font-size:11.0pt; font-family:" times="" new="" roman";mso-fareast-font-family:advtimes;mso-bidi-font-family:="" mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:="" hi"="" lang="EN-GB">mg AAEAA/100 gm FWB<span style="font-size:11.0pt; font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-bidi-font-family:mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;="" mso-bidi-language:hi"="" lang="EN-GB">) with the IC50 value = 0.88 mg/ml. Total flavonoids content was 72±2.69 and 109.73±5.91 mg quercetin equivalent (QE) /100 gm FWB for star fruit and egg fruit, respectively. Polyphenolic compounds were identified and quantified using HPLC and the data revealed the abundance of gallic acid; quercetin; ferulic acid and epi-catechin in star fruit and egg fruit extracts as well. Overall, the higher potency of star fruit in terms of radical scavenging effects is due to higher content of  total phenolics that of egg fruit. In conclusion, the <span style="font-size:11.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:minionpro-regular;mso-bidi-font-family:="" mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:="" hi"="" lang="EN-GB">results obtained from our study indicates the star fruit and egg fruit are a good source of phytochemical properties, which are nutritionally prominent for their antioxidant activities and defensive functions against diseases caused by oxidative stress, therefore can be used  in functional food formulations.</span

Synthesis of Cu-Deficient and Zn-Graded Cu–In–Zn–S Quantum Dots and Hybrid Inorganic–Organic Nanophosphor Composite for White Light Emission

Cu-deficient graded-zinc Cu–In–Zn–S (CIZS) quantum dots (QDs) were synthesized by a two-step solvothermal method. These CIZS QDs exhibited size and composition tunable photoluminescence characteristics with emission color tunable from greenish-yellow to orange to red with a relatively high quantum yield between 45 and 60%. Novel white-light-emitting (WLE) hybrid composite is fabricated by integrating the blue-emissive 1,4-bis-2-(5-phenyl oxazolyl)-benzene (POPOP) organic fluorophore and quaternary CIZS inorganic QDs. Integrating CIZS QDs with POPOP fluorophore resulted in series of tunable emission colors with CIE coordinates lying in a straight line between the coordinates of the end member. WLE was shown for hybrid mixture comprising 0.5 nM of POPOP and 3 mg/mL of CIZS QDs with color coordinates (0.3312, 0.3324). Thin films of this hybrid mixture in PMMA matrix coated on UV-LED or on glass substrates with UV backlit light also showed broadband WLE with ideal CIE color coordinates of (0.34, 0.33), high color-rendering index value of 92, and correlated color temperature value of 5143 K. The hybrid composite exhibit Forster resonance energy transfer cascading from POPOP to CIZS which results in emission covering the entire visible spectral range. POPOP and CIZS QDs hybrid composite is a versatile material for WLED applications

Hydrogen Bonds Computing Server (HBCS): an online web server to compute hydrogen-bond interactions and their precision

Hydrogen bonds in biological macromolecules play significant structural and functional roles. They are the key contributors to most of the interactions without which no living system exists. In view of this, a web-based computing server, the Hydrogen Bonds Computing Server (HBCS), has been developed to compute hydrogen-bond interactions and their standard deviations for any given macromolecular structure. The computing server is connected to a locally maintained Protein Data Bank (PDB) archive. Thus, the user can calculate the above parameters for any deposited structure, and options have also been provided for the user to upload a structure in PDB format from the client machine. In addition, the server has been interfaced with the molecular viewers Jmol and JSmol to visualize the hydrogen-bond interactions. The proposed server is freely available and accessible via the World Wide Web at http://bioserver1.physics.iisc.ernet.in/hbcs/