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Journal articleSchroeder GN, Frankel G, Tate EW, et al., 2015,
The Legionella pneumophila effector LpdA is a palmitoylated phospholipase D virulence factor
, Infection and Immunity, Vol: 83, Pages: 3989-4002, ISSN: 1098-5522Legionella pneumophila is a bacterial pathogen that thrives in alveolar macrophages, causing a severe pneumonia. The virulence of L. pneumophila depends on its Dot/Icm type IV secretion system (T4SS), which delivers more than 300 effector proteins into the host, where they rewire cellular signaling to establish a replication-permissive niche, the Legionella-containing vacuole (LCV). Biogenesis of the LCV requires substantial redirection of vesicle trafficking and remodeling of intracellular membranes. In order to achieve this, several T4SS effectors target regulators of membrane trafficking, while others resemble lipases. Here, we characterized LpdA, a phospholipase D effector, which was previously proposed to modulate the lipid composition of the LCV. We found that ectopically expressed LpdA was targeted to the plasma membrane and Rab4- and Rab14-containing vesicles. Subcellular targeting of LpdA required a C-terminal motif, which is posttranslationally modified by S-palmitoylation. Substrate specificity assays showed that LpdA hydrolyzed phosphatidylinositol, -inositol-3- and -4-phosphate, and phosphatidylglycerol to phosphatidic acid (PA) in vitro. In HeLa cells, LpdA generated PA at vesicles and the plasma membrane. Imaging of different phosphatidylinositol phosphate (PIP) and organelle markers revealed that while LpdA did not impact on membrane association of various PIP probes, it triggered fragmentation of the Golgi apparatus. Importantly, although LpdA is translocated inefficiently into cultured cells, an L. pneumophila ΔlpdA mutant displayed reduced replication in murine lungs, suggesting that it is a virulence factor contributing to L. pneumophila infection in vivo.
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Journal articleLanyon-Hogg T, Masumoto N, Bodakh G, et al., 2015,
Click chemistry armed enzyme-linked immunosorbent assay to measure palmitoylation by hedgehog acyltransferase
, Analytical Biochemistry, Vol: 490, Pages: 66-72, ISSN: 1096-0309Hedgehog signaling is critical for correct embryogenesis and tissue development. However, on maturation, signaling is also found to be aberrantly activated in many cancers. Palmitoylation of the secreted signaling protein sonic hedgehog (Shh) by the enzyme hedgehog acyltransferase (Hhat) is required for functional signaling. To quantify this important posttranslational modification, many in vitro Shh palmitoylation assays employ radiolabeled fatty acids, which have limitations in terms of cost and safety. Here we present a click chemistry armed enzyme-linked immunosorbent assay (click–ELISA) for assessment of Hhat activity through acylation of biotinylated Shh peptide with an alkyne-tagged palmitoyl-CoA (coenzyme A) analogue. Click chemistry functionalization of the alkyne tag with azido-FLAG peptide allows analysis through an ELISA protocol and colorimetric readout. This assay format identified the detergent n-dodecyl β-d-maltopyranoside as an improved solubilizing agent for Hhat activity. Quantification of the potency of RU-SKI small molecule Hhat inhibitors by click–ELISA indicated IC50 values in the low- or sub-micromolar range. A stopped assay format was also employed that allows measurement of Hhat kinetic parameters where saturating substrate concentrations exceed the binding capacity of the streptavidin-coated plate. Therefore, click–ELISA represents a nonradioactive method for assessing protein palmitoylation in vitro that is readily expandable to other classes of protein lipidation.
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Journal articleSo EC, Mattheis C, Tate EW, et al., 2015,
Creating a customized intracellular niche: subversion of host cell signaling by Legionella type IV secretion system effectors
, Canadian Journal of Microbiology, Vol: 61, Pages: 617-635, ISSN: 1480-3275The Gram-negative facultative intracellular pathogen Legionella pneumophila infects a wide range of different protozoa in the environment and also human alveolar macrophages upon inhalation of contaminated aerosols. Inside its hosts, it creates a defined and unique compartment, termed the Legionella-containing vacuole (LCV), for survival and replication. To establish the LCV, L. pneumophila uses its Dot/Icm type IV secretion system (T4SS) to translocate more than 300 effector proteins into the host cell. Although it has become apparent in the past years that these effectors subvert a multitude of cellular processes and allow Legionella to take control of host cell vesicle trafficking, transcription, and translation, the exact function of the vast majority of effectors still remains unknown. This is partly due to high functional redundancy among the effectors, which renders conventional genetic approaches to elucidate their role ineffective. Here, we review the current knowledge about Legionella T4SS effectors, highlight open questions, and discuss new methods that promise to facilitate the characterization of T4SS effector functions in the future.
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Journal articleRackham MD, Yu Z, Brannigan JA, et al., 2015,
Discovery of high affinity inhibitors of Leishmania donovani N-myristoyltransferase
, MedChemComm, Vol: 6, Pages: 1761-1766, ISSN: 2040-2511N-Myristoyltransferase (NMT) is a potential drug target in Leishmania parasites. Scaffold-hopping from published inhibitors yielded the serendipitous discovery of a chemotype selective for Leishmania donovani NMT; development led to high affinity inhibitors with excellent ligand efficiency. The binding mode was characterised by crystallography and provides a structural rationale for selectivity.
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Journal articleSerwa R, Krause E, Abaitua F, et al., 2015,
Systems analysis of protein fatty acylation in herpes simplex virus infected cells using chemical proteomics.
, Chemistry & Biology, Vol: 22, Pages: 1008-1017, ISSN: 1074-5521Protein fatty acylation regulates diverse aspects of cellular function and organization and plays a key role in host immune responses to infection. Acylation also modulates the function and localization of virus-encoded proteins. Here, we employ chemical proteomics tools, bio-orthogonal probes, and capture reagents to study myristoylation and palmitoylation during infection with herpes simplex virus (HSV). Using in-gel fluorescence imaging and quantitative mass spectrometry, we demonstrate a generalized reduction in myristoylation of host proteins, whereas palmitoylation of host proteins, including regulators of interferon and tetraspanin family proteins, was selectively repressed. Furthermore, we found that a significant fraction of the viral proteome undergoes palmitoylation; we identified a number of virus membrane glycoproteins, structural proteins, and kinases. Taken together, our results provide broad oversight of protein acylation during HSV infection, a roadmap for similar analysis in other systems, and a resource with which to pursue specific analysis of systems and functions.
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Journal articleNickel S, Serwa RA, Kaschani F, et al., 2015,
Chemoproteomic Evaluation of the Polyacetylene Callyspongynic Acid
, Chemistry-A European Journal, Vol: 21, Pages: 10721-10728, ISSN: 1521-3765Polyacetylenes are a class of alkyne-containing natural products. Although potent bioactivities and thus possible applications as chemical probes have already been reported for some polyacetylenes, insights into the biological activities or molecular mode of action are still rather limited in most cases. To overcome this limitation, we describe the application of the polyacetylene callyspongynic acid in the development of an experimental roadmap for characterizing potential protein targets of alkyne-containing natural products. To this end, we undertook the first chemical synthesis of callyspongynic acid. We then used in situ chemical proteomics methods to demonstrate extensive callyspongynic acid-mediated chemical tagging of endoplasmic reticulum-associated lipid-metabolizing and modifying enzymes. We anticipate that an elucidation of protein targets of natural products may serve as an effective guide to the development of subsequent biological assays that aim to identify chemical phenotypes and bioactivities.
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Journal articleBroncel M, Serwa RA, Ciepla P, et al., 2015,
Myristoylation profiling in human cells and zebrafish.
, Data in Brief, Vol: 4, Pages: 379-383, ISSN: 2352-3409Human cells (HEK 293, HeLa, MCF-7) and zebrafish embryos were metabolically tagged with an alkynyl myristic acid probe, lysed with an SDS buffer and tagged proteomes ligated to multifunctional capture reagents via copper-catalyzed alkyne azide cycloaddition (CuAAC). This allowed for affinity enrichment and high-confidence identification, by delivering direct MS/MS evidence for the modification site, of 87 and 61 co-translationally myristoylated proteins in human cells and zebrafish, respectively. The data have been deposited to ProteomeXchange Consortium (Vizcaíno et al., 2014 Nat. Biotechnol., 32, 223-6) (PXD001863 and PXD001876) and are described in detail in Multifunctional reagents for quantitative proteome-wide analysis of protein modification in human cells and dynamic protein lipidation during vertebrate development׳ by Broncel et al., Angew. Chem. Int. Ed.
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Journal articleBroncel M, Serwa RA, Ciepla P, et al., 2015,
Multifunctional Reagents for Quantitative Proteome-Wide Analysis of Protein Modification in Human Cells and Dynamic Profiling of Protein Lipidation During Vertebrate Development
, Angewandte Chemie-International Edition, Vol: 54, Pages: 5948-5951, ISSN: 1521-3773Novel multifunctional reagents were applied incombination with a lipid probe for affinity enrichment ofmyristoylated proteins and direct detection of lipid-modifiedtryptic peptides by mass spectrometry. This method enableshigh-confidence identification of the myristoylated proteomeon an unprecedented scale in cell culture, and allowed the firstquantitative analysis of dynamic changes in protein lipidationduring vertebrate embryonic development.
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Journal articleYusuf NA, Green JL, Wall RJ, et al., 2015,
The Plasmodium Class XIV Myosin, MyoB, Has a Distinct Subcellular Location in Invasive and Motile Stages of the Malaria Parasite and an Unusual Light Chain
, Journal of Biological Chemistry, Vol: 290, Pages: 12147-12164, ISSN: 1083-351XMyosin B (MyoB) is one of the two short class XIV myosinsencoded in the Plasmodium genome. Class XIV myosins arecharacterized by a catalytic “head,” a modified “neck,” and theabsence of a “tail” region. Myosin A (MyoA), the other class XIVmyosin in Plasmodium, has been established as a component ofthe glideosome complex important in motility and cell invasion,but MyoB is not well characterized. We analyzed the propertiesof MyoB using three parasite species as follows: Plasmodiumfalciparum, Plasmodium berghei, and Plasmodium knowlesi.MyoB is expressed in all invasive stages (merozoites, ookinetes,and sporozoites) of the life cycle, and the protein is found in adiscrete apical location in these polarized cells. In P. falciparum,MyoB is synthesized very late in schizogony/merogony, and itslocation in merozoites is distinct from, and anterior to, that of arange of known proteins present in the rhoptries, rhoptry neckor micronemes. Unlike MyoA, MyoB is not associated withglideosome complex proteins, including the MyoA light chain,myosin A tail domain-interacting protein (MTIP). A uniqueMyoB light chain (MLC-B) was identified that contains a calmodulin-likedomain at the C terminus and an extended N-terminalregion. MLC-B localizes to the same extreme apical polein the cell as MyoB, and the two proteins form a complex. Wepropose that MLC-B is a MyoB-specific light chain, and for theshort class XIV myosins that lack a tail region, the atypical myosinlight chains may fulfill that role.
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Journal articleMasumoto N, Lanyon-Hogg T, Rodgers UR, et al., 2015,
Membrane bound O-acyltransferases and their inhibitors
, Biochemical Society Transactions, Vol: 43, Pages: 246-252, ISSN: 1470-8752Since the identification of the membrane-bound O-acyltransferase (MBOATs) protein family in the early2000s, three distinct members [porcupine (PORCN), hedgehog (Hh) acyltransferase (HHAT) and ghrelin Oacyltransferase(GOAT)] have been shown to acylate specific proteins or peptides. In this review, topologydetermination, development of assays to measure enzymatic activities and discovery of small moleculeinhibitors are compared and discussed for each of these enzymes.
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Contact
Prof. Ed Tate
GSK Chair in Chemical Biology
Department of Chemistry
Molecular Sciences Research Hub, White City Campus,
82 Wood Lane, London, W12 0BZ
e.tate@imperial.ac.uk
Tel: +44 (0)20 759 + ext 43752 or 45821