Schittmayer M

References (10)

Title : Spatially resolved activity-based proteomic profiles of the murine small intestinal lipases - Schittmayer_2020_Mol.Cell.Proteomics_19_2104
Author(s) : Schittmayer M , Vujic N , Darnhofer B , Korbelius M , Honeder S , Kratky D , Birner-Gruenberger R
Ref : Mol Cell Proteomics , 19 :2104 , 2020
Abstract : Despite the crucial function of the small intestine in nutrient uptake our understanding of the molecular events underlying the digestive function is still rudimentary. Recent studies demonstrated that enterocytes do not direct the entire dietary triacylglycerol toward immediate chylomicron synthesis. Especially after high-fat challenges, parts of the resynthesized triacylglycerol are packaged into cytosolic lipid droplets for transient storage in the endothelial layer of the small intestine. The reason for this temporary storage of triacylglycerol is not completely understood. To utilize lipids from cytosolic lipid droplets for chylomicron synthesis in the endoplasmic reticulum, stored triacylglycerol has to be hydrolyzed either by cytosolic lipolysis or lipophagy. Interestingly, triacylglycerol storage and chylomicron secretion rates are unevenly distributed along the small intestine, with the proximal jejunum exhibiting the highest intermittent storage capacity. We hypothesize that correlating hydrolytic enzyme activities with the reported distribution of triacylglycerol storage and chylomicron secretion in different sections of the small intestine is a promising strategy to determine key enzymes in triacylglycerol remobilization. We employed a serine hydrolase specific activity-based labeling approach in combination with quantitative proteomics to identify and rank hydrolases based on their relative activity in 11 sections of the small intestine. Moreover, we identified several clusters of enzymes showing similar activity distribution along the small intestine. Merging our activity-based results with substrate specificity and subcellular localization known from previous studies, carboxylesterase 2e and arylacetamide deacetylase emerge as promising candidates for triacylglycerol mobilization from cytosolic lipid droplets in enterocytes.
ESTHER : Schittmayer_2020_Mol.Cell.Proteomics_19_2104
PubMedSearch : Schittmayer_2020_Mol.Cell.Proteomics_19_2104
PubMedID: 33023980

Title : PpEst is a novel PBAT degrading polyesterase identified by proteomic screening of Pseudomonas pseudoalcaligenes - Wallace_2017_Appl.Microbiol.Biotechnol_101_2291
Author(s) : Wallace PW , Haernvall K , Ribitsch D , Zitzenbacher S , Schittmayer M , Steinkellner G , Gruber K , Guebitz GM , Birner-Gruenberger R
Ref : Applied Microbiology & Biotechnology , 101 :2291 , 2017
Abstract : A novel esterase, PpEst, that hydrolyses the co-aromatic-aliphatic polyester poly(1,4-butylene adipate-co-terephthalate) (PBAT) was identified by proteomic screening of the Pseudomonas pseudoalcaligenes secretome. PpEst was induced by the presence of PBAT in the growth media and had predicted arylesterase (EC activity. PpEst showed polyesterase activity on both whole and milled PBAT film releasing terephthalic acid and 4-(4-hydroxybutoxycarbonyl)benzoic acid while end product inhibition by 4-(4-hydroxybutoxycarbonyl)benzoic acid was observed. Modelling of an aromatic polyester mimicking oligomer into the PpEst active site indicated that the binding pocket could be big enough to accommodate large polymers. This is the first report of a PBAT degrading enzyme being identified by proteomic screening and shows that this approach can contribute to the discovery of new polymer hydrolysing enzymes. Moreover, these results indicate that arylesterases could be an interesting enzyme class for identifications of polyesterases.
ESTHER : Wallace_2017_Appl.Microbiol.Biotechnol_101_2291
PubMedSearch : Wallace_2017_Appl.Microbiol.Biotechnol_101_2291
PubMedID: 27872998

Title : Lysosomal acid lipase regulates VLDL synthesis and insulin sensitivity in mice - Radovic_2016_Diabetologia_59_1743
Author(s) : Radovic B , Vujic N , Leopold C , Schlager S , Goeritzer M , Patankar JV , Korbelius M , Kolb D , Reindl J , Wegscheider M , Tomin T , Birner-Gruenberger R , Schittmayer M , Groschner L , Magnes C , Diwoky C , Frank S , Steyrer E , Du H , Graier WF , Madl T , Kratky D
Ref : Diabetologia , 59 :1743 , 2016
Abstract : AIMS/HYPOTHESIS: Lysosomal acid lipase (LAL) hydrolyses cholesteryl esters and triacylglycerols (TG) within lysosomes to mobilise NEFA and cholesterol. Since LAL-deficient (Lal (-/-) ) mice suffer from progressive loss of adipose tissue and severe accumulation of lipids in hepatic lysosomes, we hypothesised that LAL deficiency triggers alternative energy pathway(s).
METHODS: We studied metabolic adaptations in Lal (-/-) mice.
RESULTS: Despite loss of adipose tissue, Lal (-/-) mice show enhanced glucose clearance during insulin and glucose tolerance tests and have increased uptake of [(3)H]2-deoxy-D-glucose into skeletal muscle compared with wild-type mice. In agreement, fasted Lal (-/-) mice exhibit reduced glucose and glycogen levels in skeletal muscle. We observed 84% decreased plasma leptin levels and significantly reduced hepatic ATP, glucose, glycogen and glutamine concentrations in fed Lal (-/-) mice. Markedly reduced hepatic acyl-CoA concentrations decrease the expression of peroxisome proliferator-activated receptor alpha (PPARalpha) target genes. However, treatment of Lal (-/-) mice with the PPARalpha agonist fenofibrate further decreased plasma TG (and hepatic glucose and glycogen) concentrations in Lal (-/-) mice. Depletion of hepatic nuclear factor 4alpha and forkhead box protein a2 in fasted Lal (-/-) mice might be responsible for reduced expression of microsomal TG transfer protein, defective VLDL synthesis and drastically reduced plasma TG levels. CONCLUSIONS/INTERPRETATION: Our findings indicate that neither activation nor inactivation of PPARalpha per se but rather the availability of hepatic acyl-CoA concentrations regulates VLDL synthesis and subsequent metabolic adaptations in Lal (-/-) mice. We conclude that decreased plasma VLDL production enhances glucose uptake into skeletal muscle to compensate for the lack of energy supply.
ESTHER : Radovic_2016_Diabetologia_59_1743
PubMedSearch : Radovic_2016_Diabetologia_59_1743
PubMedID: 27153842

Title : Crystal structure of the Saccharomyces cerevisiae monoglyceride lipase Yju3p - Aschauer_2016_Biochim.Biophys.Acta_1861_462
Author(s) : Aschauer P , Rengachari S , Lichtenegger J , Schittmayer M , Das KM , Mayer N , Breinbauer R , Birner-Gruenberger R , Gruber CC , Zimmermann R , Gruber K , Oberer M
Ref : Biochimica & Biophysica Acta , 1861 :462 , 2016
Abstract : Monoglyceride lipases (MGLs) are a group of alpha/beta-hydrolases that catalyze the hydrolysis of monoglycerides (MGs) into free fatty acids and glycerol. This reaction serves different physiological functions, namely in the last step of phospholipid and triglyceride degradation, in mammalian endocannabinoid and arachidonic acid metabolism, and in detoxification processes in microbes. Previous crystal structures of MGLs from humans and bacteria revealed conformational plasticity in the cap region of this protein and gave insight into substrate binding. In this study, we present the structure of a MGL from Saccharomyces cerevisiae called Yju3p in its free form and in complex with a covalently bound substrate analog mimicking the tetrahedral intermediate of MG hydrolysis. These structures reveal a high conservation of the overall shape of the MGL cap region and also provide evidence for conformational changes in the cap of Yju3p. The complex structure reveals that, despite the high structural similarity, Yju3p seems to have an additional opening to the substrate binding pocket at a different position compared to human and bacterial MGL. Substrate specificities towards MGs with saturated and unsaturated alkyl chains of different lengths were tested and revealed highest activity towards MG containing a C18:1 fatty acid.
ESTHER : Aschauer_2016_Biochim.Biophys.Acta_1861_462
PubMedSearch : Aschauer_2016_Biochim.Biophys.Acta_1861_462
PubMedID: 26869448
Gene_locus related to this paper: yeast-mgll

Title : A robust and simple protocol for the synthesis of arylfluorophosphonates - Leypold_2015_Tetrahedron.Lett_56_5619
Author(s) : Leypold M , Wallace PW , Kljajic M , Schittmayer M , Pletz J , Illaszewicz-Trattner C , Guebitz GM , Birner-Gruenberger R , Breinbauer R
Ref : Tetrahedron Letters , 56 :5619 , 2015
Abstract : Abstract: Fluorophosphonates represent powerful probes for the identification and analysis of active serine hydrolases in activity based protein profiling. Although alkylphosphonofluoridates are widely used for such purposes, little is known about the synthesis and purification of arylphosphonofluoridates, which may be useful tools for screening enzyme activities toward aromatic esters. Our optimized route makes this subclass of transition state inhibitors broadly accessible for a diverse series of phosphonic acid derivatives using a combination of selective monoesterification with EDC.HCl and subsequent mild fluorination with DAST. All compounds were isolated as pure materials using a simple acid-base extraction protocol in 7693% yields over two steps. These probes can be stored under an inert atmosphere at -24C for several months without significant degradation.
ESTHER : Leypold_2015_Tetrahedron.Lett_56_5619
PubMedSearch : Leypold_2015_Tetrahedron.Lett_56_5619

Title : CGI-58\/ABHD5 is phosphorylated on Ser239 by protein kinase A: control of subcellular localization - Sahu-Osen_2015_J.Lipid.Res_56_109
Author(s) : Sahu-Osen A , Montero-Moran G , Schittmayer M , Fritz K , Dinh A , Chang YF , McMahon D , Boeszoermenyi A , Cornaciu I , Russell D , Oberer M , Carman GM , Birner-Gruenberger R , Brasaemle DL
Ref : J Lipid Res , 56 :109 , 2015
Abstract : CGI-58/ABHD5 coactivates adipose triglyceride lipase (ATGL). In adipocytes, CGI-58 binds to perilipin 1A on lipid droplets under basal conditions, preventing interaction with ATGL. Upon activation of protein kinase A (PKA), perilipin 1A is phosphorylated and CGI-58 rapidly disperses into the cytoplasm, enabling lipase coactivation. Because the amino acid sequence of murine CGI-58 has a predicted PKA consensus sequence of RKYS(239)S(240), we hypothesized that phosphorylation of CGI-58 is involved in this process. We show that Ser239 of murine CGI-58 is a substrate for PKA using phosphoamino acid analysis, MS, and immuno-blotting approaches to study phosphorylation of recombinant CGI-58 and endogenous CGI-58 of adipose tissue. Phosphorylation of CGI-58 neither increased nor impaired coactivation of ATGL in vitro. Moreover, Ser239 was not required for CGI-58 function to increase triacylglycerol turnover in human neutral lipid storage disorder fibroblasts that lack endogenous CGI-58. Both CGI-58 and S239A/S240A-mutated CGI-58 localized to perilipin 1A-coated lipid droplets in cells. When PKA was activated, WT CGI-58 dispersed into the cytoplasm, whereas substantial S239A/S240A-mutated CGI-58 remained on lipid droplets. Perilipin phosphorylation also contributed to CGI-58 dispersion. PKA-mediated phosphorylation of CGI-58 is required for dispersion of CGI-58 from perilipin 1A-coated lipid droplets, thereby increasing CGI-58 availability for ATGL coactivation.
ESTHER : Sahu-Osen_2015_J.Lipid.Res_56_109
PubMedSearch : Sahu-Osen_2015_J.Lipid.Res_56_109
PubMedID: 25421061
Gene_locus related to this paper: human-ABHD5

Title : Conformational plasticity and ligand binding of bacterial monoacylglycerol lipase - Rengachari_2013_J.Biol.Chem_288_31093
Author(s) : Rengachari S , Aschauer P , Schittmayer M , Mayer N , Gruber K , Breinbauer R , Birner-Gruenberger R , Dreveny I , Oberer M
Ref : Journal of Biological Chemistry , 288 :31093 , 2013
Abstract : Monoacylglycerol lipases (MGLs) play an important role in lipid catabolism across all kingdoms of life by catalyzing the release of free fatty acids from monoacylglycerols. The three-dimensional structures of human and a bacterial MGL were determined only recently as the first members of this lipase family. In addition to the alpha/beta-hydrolase core, they showed unexpected structural similarities even in the cap region. Nevertheless, the structural basis for substrate binding and conformational changes of MGLs is poorly understood. Here, we present a comprehensive study of five crystal structures of MGL from Bacillus sp. H257 in its free form and in complex with different substrate analogs and the natural substrate 1-lauroylglycerol. The occurrence of different conformations reveals a high degree of conformational plasticity of the cap region. We identify a specific residue, Ile-145, that might act as a gatekeeper restricting access to the binding site. Site-directed mutagenesis of Ile-145 leads to significantly reduced hydrolase activity. Bacterial MGLs in complex with 1-lauroylglycerol, myristoyl, palmitoyl, and stearoyl substrate analogs enable identification of the binding sites for the alkyl chain and the glycerol moiety of the natural ligand. They also provide snapshots of the hydrolytic reaction of a bacterial MGL at different stages. The alkyl chains are buried in a hydrophobic tunnel in an extended conformation. Binding of the glycerol moiety is mediated via Glu-156 and water molecules. Analysis of the structural features responsible for cap plasticity and the binding modes of the ligands suggests conservation of these features also in human MGL.
ESTHER : Rengachari_2013_J.Biol.Chem_288_31093
PubMedSearch : Rengachari_2013_J.Biol.Chem_288_31093
PubMedID: 24014019
Gene_locus related to this paper: bac25-mglp

Title : Lipolytic proteomics - Schittmayer_2012_Mass.Spectrom.Rev_31_570
Author(s) : Schittmayer M , Birner-Gruenberger R
Ref : Mass Spectrom Rev , 31 :570 , 2012
Abstract : Activity-based proteomics (ABP) employs small molecular probes to specifically label sets of enzymes based on their shared catalytic mechanism. Given that the vast majority of lipases belong to the family of serine hydrolases and share a nucleophilic active-site serine as part of a catalytic triad, activity-based probes are ideal tools to study lipases and lipolysis. Moreover, the ability of ABP to highlight or isolate specific subproteomes results in a massive decrease of sample complexity. Thereby, in-depth analysis of enzymes of interest with mass spectrometry becomes feasible. In this review, we cover probe design, technological developments, and applications of ABP of lipases, as well as give an overview of relevant identified proteins.
ESTHER : Schittmayer_2012_Mass.Spectrom.Rev_31_570
PubMedSearch : Schittmayer_2012_Mass.Spectrom.Rev_31_570
PubMedID: 22392637

Title : Activity based subcellular resolution imaging of lipases - Viertler_2012_Bioorg.Med.Chem_20_628
Author(s) : Viertler M , Schittmayer M , Birner-Gruenberger R
Ref : Bioorganic & Medicinal Chemistry , 20 :628 , 2012
Abstract : Lipases play a key role in whole body energy homeostasis. Dysregulation of lipolytic activities affects lipid absorption, mobilization, and transport, and is causative for lipid-related diseases. Regulation of enzymes involved in lipid metabolism is governed by a complex network of protein-protein and protein-small molecule interactions. Thus these enzymes have to be studied under the physiologically most relevant conditions, that is, in vivo. Our latest generation of activity based probes designed for capturing of lipases employs bioorthogonal chemical linker groups, which are membrane permeable and thus allow studying protein activity in living cells. Another advantage is the virtually unlimited choice of reporter tags. Here we report on a novel method combining in vivo activity based labeling of lipases with in situ detection of lipolytic activities by on slide click chemistry and imaging by fluorescence microscopy. We demonstrate that cytosolic as well as organelle resident lipases are specifically labeled in intact living cells. This method will shed light on the (sub)cellular localization of lipolytic proteomes of cells and tissues in health and disease directly at enzymatic activity level without the need of prior knowledge of the identities of the responsible enzymes or dependence on the availability of specific antibodies.
ESTHER : Viertler_2012_Bioorg.Med.Chem_20_628
PubMedSearch : Viertler_2012_Bioorg.Med.Chem_20_628
PubMedID: 21570307

Title : Functional proteomics in lipid research: lipases, lipid droplets and lipoproteins - Schittmayer_2009_J.Proteomics_72_1006
Author(s) : Schittmayer M , Birner-Gruenberger R
Ref : J Proteomics , 72 :1006 , 2009
Abstract : Lipids are the major energy source of humans. Their digestion, transport, formation, intracellular storage and mobilization are tightly controlled processes to ensure overall energy balance. Here we review discovery and investigation of lipases, which are key players in hydrolysis of lipids, by proteomic means. In particular, we cover the use of activity based probes for functional analysis of these enzymes. The regulation of lipolytic activity is crucial to ensure energy balance and to avoid lipotoxic effects as exerted by products of lipolysis such as free fatty acids. Therefore, transcriptional and post-translational regulation are involved in the equilibrium between lipid storage and mobilization. Moreover, substrate accessibility, which may be governed by localization of lipases, is a key regulatory element. Lipid transport as well as lipid synthesis, storage and mobilization is facilitated by complex lipid-protein assemblies, namely lipoproteins and lipid droplets. Proteomic studies of these particles have uncovered protein factors involved in their assembly and transport, but also in lipid synthesis and mobilization.
ESTHER : Schittmayer_2009_J.Proteomics_72_1006
PubMedSearch : Schittmayer_2009_J.Proteomics_72_1006
PubMedID: 19477308