scholarly journals Inositol lipid synthesis is widespread in host-associated Bacteroidetes

2021 ◽  
Author(s):  
S. L. Heaver ◽  
H. H. Le ◽  
P. Tang ◽  
A. Baslé ◽  
J. Marles-Wright ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Biosynthetic Pathway ◽  
Inositol Phosphate ◽  
Lipid Production ◽  
Lipid Synthesis ◽  
Kinetic Studies ◽  
Human Gut ◽  
Host Interactions ◽  
Phosphatidylinositol Phosphate ◽  
Inositol Lipids

AbstractUbiquitous in eukaryotes, inositol lipids have finely tuned roles in cellular signaling and membrane homeostasis. In Bacteria, however, inositol lipid production is rare. Recently, the prominent human gut bacterium Bacteroides thetaiotaomicron (BT) was reported to produce inositol lipids, including inositol sphingolipids, but the pathways remain ambiguous and their prevalence unclear. Here, we investigated the gene cluster responsible for inositol lipid synthesis in BT using a novel strain with inducible control of sphingolipid synthesis. We characterized the biosynthetic pathway from myo-inositol-phosphate (MIP) synthesis to phosphoinositol-dihydroceramide, including structural and kinetic studies of the enzyme MIP synthase (MIPS). We determined the crystal structure of recombinant BT MIPS with bound NAD cofactor at 2.0 Å resolution, and identified the first reported phosphatase for the conversion of bacterially-derived phosphatidylinositol phosphate (PIP) to phosphatidylinositol (PI). Transcriptomic analysis indicated inositol production is nonessential but its loss alters BT capsule expression. Bioinformatic and lipidomic comparisons of Bacteroidetes species revealed a novel second putative pathway for bacterial PI synthesis without a PIP intermediate. Our results indicate that inositol sphingolipid production, via one of the two pathways, is widespread in host-associated Bacteroidetes, and may be implicated in host interactions both indirectly via the capsule and directly through inositol lipid provisioning.

scholarly journals Adhesion to fibronectin stimulates inositol lipid synthesis and enhances PDGF-induced inositol lipid breakdown.

1993 ◽  
Vol 121 (3) ◽  
pp. 673-678 ◽  
Author(s):  
H P McNamee ◽  
D E Ingber ◽  
M A Schwartz
Keyword(s):  
Inositol Phosphates ◽  
Inositol Phosphate ◽  
Second Messengers ◽  
Lipid Synthesis ◽  
Water Soluble ◽  
Phosphatidylinositol Bisphosphate ◽  
Hydrolysis Products ◽  
Cytoskeletal Regulation ◽  
Inositol Lipids ◽  
Suspended Cells

The aim of these experiments was to investigate whether inositol lipids might mediate some of the effects of extracellular matrix (ECM) on cellular form and functions. The lipid phosphatidylinositol bisphosphate (PIP2) plays a role in cytoskeletal regulation while its hydrolysis products, diacylglycerol and inositol triphosphate, serve as second messengers. We therefore measured the effect of adhesion to fibronectin (FN) on PIP2 and its hydrolysis products, in the presence and absence of the soluble mitogen PDGF. PDGF induced a threefold increase in release of water-soluble inositol phosphates in C3H 10T1/2 fibroblasts when cells were attached to FN, but had little effect in suspended cells. Suppression of inositol phosphate release in unattached cells was not due to dysfunction of the PDGF receptor or failure to activate phospholipase C-gamma; PDGF induced similar tyrosine phosphorylation of PLC-gamma under both conditions. By contrast, the total mass of phosphatidylinositol bisphosphate (PIP2), the substrate for PLC-gamma, was found to decrease by approximately 80% when cells were detached from their ECM attachments and placed in suspension in the absence of PDGF. PIP2 levels were restored when suspended cells were replated on FN, demonstrating that the effect was reversible. Furthermore, a dramatic increase in synthesis of PIP2 could be measured in cells within 2 min after reattachment to FN in the absence of PDGF. These results show that FN acts directly to stimulate PIP2 synthesis, and that it also enhances PIP2 hydrolysis in response to PDGF. The increase in PIP2 induced by adhesion may mediate some of the known effects of FN on cell shape and cytoskeletal organization, while regulation of inositol lipid hydrolysis may provide a means for integrating hormone- and ECM-dependent signaling pathways.

scholarly journals The 1.6 Å Crystal Structure ofMycobacterium smegmatisMshC: The Penultimate Enzyme in the Mycothiol Biosynthetic Pathway†

Biochemistry ◽  
2008 ◽  
Vol 47 (50) ◽  
pp. 13326-13335 ◽  
Author(s):  
L. W. Tremblay ◽  
F. Fan ◽  
M. W. Vetting ◽  
J. S. Blanchard
Keyword(s):  
Crystal Structure ◽  
Biosynthetic Pathway

scholarly journals Hydrogen peroxide‐mediated conversion of coproheme to heme b by HemQ—lessons from the first crystal structure and kinetic studies

FEBS Journal ◽  
2016 ◽  
Vol 283 (23) ◽  
pp. 4386-4401 ◽  
Author(s):  
Stefan Hofbauer ◽  
Georg Mlynek ◽  
Lisa Milazzo ◽  
Dominic Pühringer ◽  
Daniel Maresch ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Peroxide ◽  
Kinetic Studies

Crystal Structure of Vancosaminyltransferase GtfD from the Vancomycin Biosynthetic Pathway:  Interactions with Acceptor and Nucleotide Ligands†,‡

Biochemistry ◽  
2004 ◽  
Vol 43 (18) ◽  
pp. 5170-5180 ◽  
Author(s):  
Anne M. Mulichak ◽  
Wei Lu ◽  
Heather C. Losey ◽  
Christopher T. Walsh ◽  
R. Michael Garavito
Keyword(s):  
Crystal Structure ◽  
Biosynthetic Pathway

scholarly journals Crystal structure of dipeptidyl peptidase III from the human gut symbiont Bacteroides thetaiotaomicron

PLoS ONE ◽  
2017 ◽  
Vol 12 (11) ◽  
pp. e0187295 ◽  
Author(s):  
Igor Sabljić ◽  
Nevenka Meštrović ◽  
Bojana Vukelić ◽  
Peter Macheroux ◽  
Karl Gruber ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Dipeptidyl Peptidase ◽  
Bacteroides Thetaiotaomicron ◽  
Human Gut

scholarly journals miR-15b negatively correlates with lipid metabolism in mammary epithelial cells

2018 ◽  
Vol 314 (1) ◽  
pp. C43-C52 ◽  
Author(s):  
Meiqiang Chu ◽  
Yong Zhao ◽  
Shuai Yu ◽  
Yanan Hao ◽  
Pengfei Zhang ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Epithelial Cells ◽  
Steroid Hormones ◽  
Lipid Content ◽  
Mammary Epithelial Cells ◽  
Lipid Production ◽  
Fatty Acid Synthetase ◽  
Lipid Synthesis ◽  
Mammary Epithelial ◽  
Lipid Formation

Mammary epithelial cells are regulated by steroid hormones, growth factors, and even microRNAs. miR-15b has been found to regulate lipid metabolism in adipocytes; however, its effects on lipid metabolism in mammary epithelial cells, the cells of lipid synthesis and secretion, are as yet unknown. The main purpose of this investigation was to explore the effect of miR-15b on lipid metabolism in mammary epithelial cells, along with the underlying mechanisms. miR-15b was overexpressed or inhibited by miRNA mimics or inhibitors; subsequently, lipid formation in mammary epithelial cells, and proteins related to lipid metabolism, were investigated. Through overexpression or inhibition of miR-15b expression, the current investigation found that miR-15b downregulates lipid metabolism in mammary epithelial cells and is expressed differentially at various stages of mouse and goat mammary gland development. Inhibition of miR-15b expression increased lipid content in mammary epithelial cells through elevation of the lipid synthesis enzyme fatty acid synthetase (FASN), and overexpression of miR-15b reduced lipid content in mammary epithelial cells with decreasing levels of FASN. Moreover, the steroid hormones estradiol and progesterone decreased miR-15b expression with a subsequent increase in lipid formation in mammary epithelial cells. The expression of miR-15b was lower during lactation and negatively correlated with lipid synthesis proteins, which suggests that it may be involved in lipid synthesis and milk production. miR-15b might be a useful target for altering lipid production and milk yield.

scholarly journals The Arabidopsis locus AT3G03890 encodes a dimeric β-barrel protein implicated in heme degradation

2020 ◽  
Vol 477 (24) ◽  
pp. 4785-4796
Author(s):  
Jia Wang ◽  
Qi Guo ◽  
Xiaoyi Li ◽  
Xiao Wang ◽  
Lin Liu
Keyword(s):  
Crystal Structure ◽  
Recombinant Protein ◽  
Water Molecule ◽  
Heme Oxygenase ◽  
Protein Complex ◽  
Biosynthetic Pathway ◽  
Initial Step ◽  
Heme Iron ◽  
Heme Binding ◽  
New Protein

Plant tetrapyrroles, including heme and bilins, are synthesized in plastids. Heme oxygenase (HO) catalyzes the oxidative cleavage of heme to the linear tetrapyrrole biliverdin as the initial step in bilin biosynthesis. Besides the canonical α-helical HO that is conserved from prokaryotes to human, a subfamily of non-canonical dimeric β-barrel HO has been found in bacteria. In this work, we discovered that the Arabidopsis locus AT3G03890 encodes a dimeric β-barrel protein that is structurally related to the putative non-canonical HO and is located in chloroplasts. The recombinant protein was able to bind and degrade heme in a manner different from known HO proteins. Crystal structure of the heme–protein complex reveals that the heme-binding site is in the interdimer interface and the heme iron is co-ordinated by a fixed water molecule. Our results identify a new protein that may function additionally in the tetrapyrrole biosynthetic pathway.

scholarly journals Structure of theMycobacterium tuberculosisd-Alanine:d-Alanine Ligase, a Target of the Antituberculosis Drug d-Cycloserine

2010 ◽  
Vol 55 (1) ◽  
pp. 291-301 ◽  
Author(s):  
John B. Bruning ◽  
Ana C. Murillo ◽  
Ofelia Chacon ◽  
Raúl G. Barletta ◽  
James C. Sacchettini
Keyword(s):  
Crystal Structure ◽  
Binding Site ◽  
Kinetic Studies ◽  
Structural Rearrangement ◽  
Peptidoglycan Biosynthesis ◽  
Binding Cavity ◽  
Binding Pockets ◽  
Loop Regions ◽  
Discrete Domains ◽  
Alanine Dipeptide

ABSTRACTd-Alanine:d-alanine ligase (EC 6.3.2.4; Ddl) catalyzes the ATP-driven ligation of twod-alanine (d-Ala) molecules to form thed-alanyl:d-alanine dipeptide. This molecule is a key building block in peptidoglycan biosynthesis, making Ddl an attractive target for drug development.d-Cycloserine (DCS), an analog ofd-Ala and a prototype Ddl inhibitor, has shown promise for the treatment of tuberculosis. Here, we report the crystal structure ofMycobacterium tuberculosisDdl at a resolution of 2.1 Å. This structure indicates that Ddl is a dimer and consists of three discrete domains; the ligand binding cavity is at the intersection of all three domains and conjoined by several loop regions. TheM. tuberculosisapo Ddl structure shows a novel conformation that has not yet been observed in Ddl enzymes from other species. The nucleotide andd-alanine binding pockets are flexible, requiring significant structural rearrangement of the bordering regions for entry and binding of both ATP andd-Ala molecules. Solution affinity and kinetic studies showed that DCS interacts with Ddl in a manner similar to that observed ford-Ala. Each ligand binds to two binding sites that have significant differences in affinity, with the first binding site exhibiting high affinity. DCS inhibits the enzyme, with a 50% inhibitory concentration (IC50) of 0.37 mM under standard assay conditions, implicating a preferential and weak inhibition at the second, lower-affinity binding site. Moreover, DCS binding is tighter at higher ATP concentrations. The crystal structure illustrates potential drugable sites that may result in the development of more-effective Ddl inhibitors.

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