scholarly journals Widespread Head-to-Head Hydrocarbon Biosynthesis in Bacteria and Role of OleA

2010 ◽  
Vol 76 (12) ◽  
pp. 3850-3862 ◽  
Author(s):  
David J. Sukovich ◽  
Jennifer L. Seffernick ◽  
Jack E. Richman ◽  
Jeffrey A. Gralnick ◽  
Lawrence P. Wackett
Keyword(s):  
Xanthomonas Campestris ◽  
Gene Deletion ◽  
Shewanella Oneidensis ◽  
Fatty Acyl ◽  
Double Bonds ◽  
Acyl Chains ◽  
Hydrocarbon Biosynthesis ◽  
Structural Alignments ◽  
Long Chain

ABSTRACT Previous studies identified the oleABCD genes involved in head-to-head olefinic hydrocarbon biosynthesis. The present study more fully defined the OleABCD protein families within the thiolase, α/β-hydrolase, AMP-dependent ligase/synthase, and short-chain dehydrogenase superfamilies, respectively. Only 0.1 to 1% of each superfamily represents likely Ole proteins. Sequence analysis based on structural alignments and gene context was used to identify highly likely ole genes. Selected microorganisms from the phyla Verucomicrobia, Planctomyces, Chloroflexi, Proteobacteria, and Actinobacteria were tested experimentally and shown to produce long-chain olefinic hydrocarbons. However, different species from the same genera sometimes lack the ole genes and fail to produce olefinic hydrocarbons. Overall, only 1.9% of 3,558 genomes analyzed showed clear evidence for containing ole genes. The type of olefins produced by different bacteria differed greatly with respect to the number of carbon-carbon double bonds. The greatest number of organisms surveyed biosynthesized a single long-chain olefin, 3,6,9,12,15,19,22,25,28-hentriacontanonaene, that contains nine double bonds. Xanthomonas campestris produced the greatest number of distinct olefin products, 15 compounds ranging in length from C28 to C31 and containing one to three double bonds. The type of long-chain product formed was shown to be dependent on the oleA gene in experiments with Shewanella oneidensis MR-1 ole gene deletion mutants containing native or heterologous oleA genes expressed in trans. A strain deleted in oleABCD and containing oleA in trans produced only ketones. Based on these observations, it was proposed that OleA catalyzes a nondecarboxylative thiolytic condensation of fatty acyl chains to generate a β-ketoacyl intermediate that can decarboxylate spontaneously to generate ketones.

scholarly journals Active Multienzyme Assemblies for Long-Chain Olefinic Hydrocarbon Biosynthesis

2017 ◽  
Vol 199 (9) ◽  
Author(s):  
James K. Christenson ◽  
Matthew R. Jensen ◽  
Brandon R. Goblirsch ◽  
Fatuma Mohamed ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Xanthomonas Campestris ◽  
Fatty Acyl ◽  
Biosynthetic Activity ◽  
Content Type ◽  
Large Structures ◽  
Negative Stain ◽  
Acyl Coenzyme A ◽  
Hydrocarbon Biosynthesis ◽  
Long Chain

ABSTRACT Bacteria from different phyla produce long-chain olefinic hydrocarbons derived from an OleA-catalyzed Claisen condensation of two fatty acyl coenzyme A (acyl-CoA) substrates, followed by reduction and oxygen elimination reactions catalyzed by the proteins OleB, OleC, and OleD. In this report, OleA, OleB, OleC, and OleD were individually purified as soluble proteins, and all were found to be essential for reconstituting hydrocarbon biosynthesis. Recombinant coexpression of tagged OleABCD proteins from Xanthomonas campestris in Escherichia coli and purification over His6 and FLAG columns resulted in OleA separating, while OleBCD purified together, irrespective of which of the four Ole proteins were tagged. Hydrocarbon biosynthetic activity of copurified OleBCD assemblies could be reconstituted by adding separately purified OleA. Immunoblots of nondenaturing gels using anti-OleC reacted with X. campestris crude protein lysate indicated the presence of a large protein assembly containing OleC in the native host. Negative-stain electron microscopy of recombinant OleBCD revealed distinct large structures with diameters primarily between 24 and 40 nm. Assembling OleB, OleC, and OleD into a complex may be important to maintain stereochemical integrity of intermediates, facilitate the movement of hydrophobic metabolites between enzyme active sites, and protect the cell against the highly reactive β-lactone intermediate produced by the OleC-catalyzed reaction. IMPORTANCE Bacteria biosynthesize hydrophobic molecules to maintain a membrane, store carbon, and for antibiotics that help them survive in their niche. The hydrophobic compounds are often synthesized by a multidomain protein or by large multienzyme assemblies. The present study reports on the discovery that long-chain olefinic hydrocarbons made by bacteria from different phyla are produced by multienzyme assemblies in X. campestris. The OleBCD multienzyme assemblies are thought to compartmentalize and sequester olefin biosynthesis from the rest of the cell. This system provides additional insights into how bacteria control specific biosynthetic pathways.

How do mechanosensitive channels sense membrane tension?

2016 ◽  
Vol 44 (4) ◽  
pp. 1019-1025 ◽  
Author(s):  
Tim Rasmussen
Keyword(s):  
Membrane Lipids ◽  
Osmotic Shock ◽  
Md Simulations ◽  
Fatty Acyl ◽  
Membrane Bilayer ◽  
Cross Sectional ◽  
Conducting Path ◽  
Lipid Chain ◽  
Acyl Chains

Mechanosensitive (MS) channels provide protection against hypo-osmotic shock in bacteria whereas eukaryotic MS channels fulfil a multitude of important functions beside osmoregulation. Interactions with the membrane lipids are responsible for the sensing of mechanical force for most known MS channels. It emerged recently that not only prokaryotic, but also eukaryotic, MS channels are able to directly sense the tension in the membrane bilayer without any additional cofactor. If the membrane is solely viewed as a continuous medium with specific anisotropic physical properties, the sensitivity towards tension changes can be explained as result of the hydrophobic coupling between membrane and transmembrane (TM) regions of the channel. The increased cross-sectional area of the MS channel in the active conformation and elastic deformations of the membrane close to the channel have been described as important factors. However, recent studies suggest that molecular interactions of lipids with the channels could play an important role in mechanosensation. Pockets in between TM helices were identified in the MS channel of small conductance (MscS) and YnaI that are filled with lipids. Less lipids are present in the open state of MscS than the closed according to MD simulations. Thus it was suggested that exclusion of lipid fatty acyl chains from these pockets, as a consequence of increased tension, would trigger gating. Similarly, in the eukaryotic MS channel TRAAK it was found that a lipid chain blocks the conducting path in the closed state. The role of these specific lipid interactions in mechanosensation are highlighted in this review.

scholarly journals Increased fatty acyl saturation of phosphatidylinositol phosphates in prostate cancer progression

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Atsushi Koizumi ◽  
Shintaro Narita ◽  
Hiroki Nakanishi ◽  
Masaki Ishikawa ◽  
Satoshi Eguchi ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Cancer Progression ◽  
Fatty Acyl ◽  
Human Prostate ◽  
Pathological Stage ◽  
Double Bonds ◽  
Prostate Hyperplasia ◽  
Cellular Processes ◽  
Acyl Chains ◽  
Phosphatidylinositol Phosphates

Abstract Phosphoinositides (PIPs) participate in many cellular processes, including cancer progression; however, the metabolic features of PIPs associated with prostate cancer (PCa) are unknown. We investigated PIPs profiles in PTEN-deficient prostate cancer cell lines, human prostate tissues obtained from patients with PCa and benign prostate hyperplasia (BPH) specimens using mass spectrometry. In immortalized normal human prostate PNT1B cells, PTEN deficiency increased phosphatidylinositol tris-phosphate (PIP3) and decreased phosphatidylinositol mono- and bis-phosphate (PIP1 and PIP2), consistent with PTEN’s functional role as a PI(3,4,5)P3 3-phosphatase. In human prostate tissues, levels of total (sum of all acyl variants) phosphatidylinositol (PI) and PIP1 in PCa were significantly higher than in BPH, whereas PIP2 and PIP3 contents were significantly lower than in BPH. PCa patients had significantly higher proportion of PI, PIP1, and PIP2 with 0–2 double bonds in acyl chains than BPH patients. In subgroup analyses based on PCa aggressiveness, mean total levels of PI with 0–2 double bonds in acyl chains were significantly higher in patients with pathological stage T3 than in those with pathological stage T2. These data indicate that alteration of PIPs level and the saturation of acyl chains may be associated with the development and aggressiveness of prostate cancer, although it is unknown whether this alteration is causative.

scholarly journals Engineering Long-Range Order in Supramolecular Assemblies on Surfaces: The Paramount Role of Internal Double Bonds in Discrete Long-Chain Naphthalenediimides

2020 ◽  
Vol 142 (8) ◽  
pp. 4070-4078 ◽  
Author(s):  
José Augusto Berrocal ◽  
G. Henrieke Heideman ◽  
Bas F. M. de Waal ◽  
Mihaela Enache ◽  
Remco W. A. Havenith ◽  
...  
Keyword(s):  
Long Range ◽  
Supramolecular Assemblies ◽  
Range Order ◽  
Long Range Order ◽  
Double Bonds ◽  
Long Chain

scholarly journals A conserved evolutionary mechanism permits Δ9 desaturation of very-long-chain fatty acyl lipids

2020 ◽  
Vol 295 (32) ◽  
pp. 11337-11345
Author(s):  
Yuanheng Cai ◽  
Xiao-Hong Yu ◽  
Jin Chai ◽  
Chang-Jun Liu ◽  
John Shanklin
Keyword(s):  
Binding Pocket ◽  
Fatty Acyl ◽  
Single Amino Acid ◽  
Side Chain ◽  
Surface Residue ◽  
Binding Cavity ◽  
Acyl Lipids ◽  
Acyl Chains ◽  
Long Chain ◽  
Bulky Side Chain

Δ9 fatty acyl desaturases introduce a cis–double bond between C9 and C10 of saturated fatty acyl chains. From the crystal structure of the mouse stearoyl-CoA desaturase (mSCD1) it was proposed that Tyr-104, a surface residue located at the distal end of the fatty acyl binding pocket plays a key role in specifying 18C selectivity. We created mSCD1-Y104G to test the hypothesis that eliminating this bulky side chain would create an opening and permit the substrate's methyl end to protrude through the enzyme into the lipid bilayer, facilitating the desaturation of very-long-chain (VLC) substrates. Consistent with this hypothesis, Y104G acquired the ability to desaturate 24C and 26C acyl-CoAs while maintaining its Δ9-regioselectivity. We also investigated two distantly related very-long-chain fatty acyl (VLCFA) desaturases from Arabidopsis, ADS1.2 and ADS1.4, which have Ala and Gly, respectively, in place of the gatekeeping Tyr found in mSCD1. Substitution of Tyr for Ala and Gly in ADS1.2 and ADS1.4, respectively, blocked their ability to desaturate VLCFAs. Further, we identified a pair of fungal desaturase homologs which contained either an Ile or a Gly at this location and showed that only the Gly-containing desaturase was capable of very-long-chain desaturation. The conserved desaturase architecture wherein a surface residue with a single bulky side chain forms the end of the substrate binding cavity predisposes them to single amino acid substitutions that enable a switch between long- and very-long-chain selectivity. The data presented here show that such changes have independently occurred multiple times during evolution.

scholarly journals The Role of Long-Chain Fatty Acyl-CoA Esters in β-Cell Signal Transduction

2000 ◽  
Vol 130 (2) ◽  
pp. 299S-304S ◽  
Author(s):  
Barbara E. Corkey ◽  
Jude T. Deeney ◽  
Gordon C. Yaney ◽  
Keith Tornheim ◽  
Marc Prentki
Keyword(s):  
Signal Transduction ◽  
Fatty Acyl ◽  
Β Cell ◽  
Cell Signal ◽  
Cell Signal Transduction ◽  
Long Chain

The Role of the Mitochondrial Citrate Transporter in the Regulation of Fatty Acid Synthesis: Effect of Fasting and Diabetes

1973 ◽  
Vol 51 (11) ◽  
pp. 1542-1544 ◽  
Author(s):  
Surinder Cheema-Dhadli ◽  
Mitchell L. Halperin
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Acid Synthesis ◽  
Fatty Acyl ◽  
Diabetic Rats ◽  
Michaelis Constant ◽  
Citrate Transporter ◽  
Long Chain

The Michaelis constant (Km) for citrate for the hepatic mitochondrial citrate transporter of fed rats is 239 μM. This Km increases approximately twofold in mitochondria of fasted or diabetic rats. The long-chain fatty acyl-CoA content was approximately twofold higher in mitochondria from fasted and diabetic rats and could account for this increased Km. The role of regulation of the mitochondrial citrate transporter in lipogenesis is discussed.

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