Dennis R Voelker

United States Department of Veterans Affairs, Бедфорд, Massachusetts, United States

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Publications (183)878.6 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Phosphatidylserine decarboxylases (PSDs) play a central role in the synthesis of phosphatidylethanolamine in numerous species of prokaryotes and eukaryotes. PSDs are unusual decarboxylases containing a pyruvoyl prosthetic group within the active site. The covalently attached pyruvoyl moiety is formed in a concerted reaction when the PSD proenzyme undergoes an endoproteolytic cleavage into a large β-subunit, and a smaller α-subunit, which harbors the prosthetic group at its N-terminus. The mechanism of PSD proenzyme cleavage has long been unclear. Using a coupled in vitro transcription/ translation system with the soluble Plasmodium knowlesi enzyme (PkPSD), we demonstrate that the post-translational processing is inhibited by the serine protease inhibitor, phenylmethylsulfonyl fluoride. Comparison of PSD sequences across multiple phyla reveals a uniquely conserved aspartic acid within an FFxRx6Rx12PxD motif, two uniquely conserved histidine residues within a PxxYHxxHxP motif, and a uniquely conserved serine residue within a GSS/T motif, suggesting that PSDs belong to the D-H-S serine protease family. The function of the conserved D-H-S residues was probed using site directed mutagenesis of PkPSD. The results from these mutagenesis experiments reveal that D139, H198 and S308 are all essential for endoproteolytic processing of PkPSD, which occurs in cis. In addition, within the GSS/T motif found in all PSDs, the G307 residue is also essential, but the S/T 309 is non-essential. These results define the mechanism whereby PSDs begin their biochemical existence as proteases that execute one autoendoproteolytic cleavage reaction to give rise to a mature PSD harboring a pyruvoyl prosthetic group. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    The Journal of biological chemistry. 02/2015;
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    ABSTRACT: Chemical reactions with unsaturated phospholipids in the respiratory tract lining fluid have been identified as one of the first important steps in the mechanisms mediating environmental ozone toxicity. As a consequence of these reactions, complex mixtures of oxidized lipids are generated in the presence of mixtures of non-oxidized naturally occurring phospholipid molecular species, which challenge methods of analysis. Untargeted mass spectrometry and statistical methods were employed to approach these complex spectra. Human bronchoalveolar lavage (BAL) was exposed to low levels of ozone and samples, with and without derivatization of aldehydes, were analyzed by liquid chromatography electrospray ionization tandem mass spectrometry. Data processing was carried out using principal component analysis (PCA). Resulting PCA score plots indicated an ozone dose-dependent increase, with apparent separation between BAL samples exposed to 60 ppb ozone and non-exposed BAL samples, and a clear separation between ozonized samples before and after derivatization. Corresponding loadings plots revealed that more than 30 phosphatidylcholine (PC) species decreased due to ozonation. A total of 13 PC and 6 phosphatidylglycerol oxidation products were identified with the majority being structurally characterized as chain-shortened aldehyde products. This method exemplifies an approach for comprehensive detection of low abundance, yet important, components in complex lipid samples.
    Analytical Biochemistry 01/2015; · 2.31 Impact Factor
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    ABSTRACT: Respiratory syncytial virus (RSV) infects nearly all children under age 2, and reinfection occurs throughout life, seriously impacting adults with chronic pulmonary diseases. Recent data demonstrate the anionic pulmonary surfactant lipid, phosphatidylglycerol (PG), exerts a potent anti-viral effect against RSV in vitro and in vivo. Phosphatidylinositol (PI) is also an anionic pulmonary surfactant phospholipid, and we tested its anti-viral activity. PI liposomes completely suppress interleukin 8 production from BEAS2B epithelial cells challenged with RSV. The presence of PI during viral challenge in vitro reduces infection by a factor of >103. PI binds RSV with high affinity, preventing virus attachment to epithelial cells. Intranasal inoculation with PI along with RSV in mice, reduces the viral burden 30-fold, eliminates the influx of inflammatory cells, and reduces tissue histopathology. Pharmacological doses of PI persist for >6 hrs in mouse lung. Pretreatment of mice with PI at 2 hrs prior to viral infection effectively suppresses inflammation and reduces the viral burden by 85%. These data demonstrate PI has potent anti-viral properties, a long residence time in the extracellular bronchoalveolar compartment, and a significant prophylaxis window. The findings demonstrate the PG and PI have complementary roles as intrinsic, innate immune anti-viral mediators in the lung. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Journal of lipid research. 01/2015;
  • Muthukumar Kannan, Wayne R. Riekhof, Dennis R. Voelker
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    ABSTRACT: Over the past two decades, most of the genes specifying lipid synthesis and metabolism in yeast have been identified and characterized. Several of these biosynthetic genes and their encoded enzymes have provided valuable tools for the genetic and biochemical dissection of interorganelle lipid transport processes in yeast. One such pathway involves the synthesis of phosphatidylserine (PtdSer) in the endopasmic reticulum (ER), and its non-vesicular transport to the site of phosphatidylserine decarboxylase 2 (Psd2p) in membranes of the Golgi and endosomal sorting system. In this review, we summarize the identification and characterization of the yeast phosphatidylserine decarboxylases, and examine their role in studies of the transport-dependent pathways of de novo synthesis of phosphatidylethanolamine (PtdEtn). The emerging picture of the Psd2p specific transport pathway is one in which the enzyme and its non-catalytic N-terminal domains act as a hub to nucleate the assembly of a multi-protein complex, which facilitates PtdSer transport at membrane contact sites between the ER and Golgi/endosome membranes. After transport to the catalytic site of Psd2p, PtdSer is decarboxylated to form PtdEtn, which is disseminated throughout the cell to support the structural and functional needs of multiple membranes.
    Traffic 10/2014; · 4.71 Impact Factor
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    ABSTRACT: The short palate, lung and nasal epithelial clone 1 (SPLUNC1) protein is a member of the palate, lung, and nasal epithelium clone (PLUNC) family, also known as bactericidal/permeability-increasing (BPI) fold-containing protein, family A, member 1 (BPIFA1). SPLUNC1 is an abundant protein in human airways, but its function remains poorly understood. The lipid ligands of SPLUNC1 as well as other PLUNC family members are largely unknown, although some reports provide evidence that lipopolysaccharide (LPS) could be a lipid ligand. Unlike previous hypotheses, we found significant structural differences between SPLUNC1 and BPI. Recombinant SPLUNC1 produced in HEK 293 cells harbored several molecular species of sphingomyelin and phosphatidylcholine as its ligands. Significantly, in vitro lipid-binding studies failed to demonstrate interactions between SPLUNC1 and LPS, lipoteichoic acid, or polymyxin B. Instead, one of the major and most important pulmonary surfactant phospholipids, dipalmitoylphosphatidylcholine (DPPC), bound to SPLUNC1 with high affinity and specificity. We found that SPLUNC1 could be the first protein receptor for DPPC. These discoveries provide insight into the specific determinants governing the interaction between SPLUNC1 and lipids and also shed light on novel functions that SPLUNC1 and other PLUNC family members perform in host defense.-Ning, F., Wang, C., Berry, K. Z., Kandasamy, P., Liu, H., Murphy, R. C., Voelker, D. R., Nho, C. W., Pan, C.-H., Dai, S., Niu, L., Chu, H-W., Zhang, G. Structural characterization of the pulmonary innate immune protein SPLUNC1 and identification of lipid ligands.
    The FASEB Journal 09/2014; · 5.48 Impact Factor
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    ABSTRACT: Pulmonary surfactant protein A (SP-A), a heterooligomer of SP-A1 and SP-A2, is an important regulator of innate immunity of the lung. Nonsynonymous single nucleotide variants of SP-A have been linked to respiratory diseases, but the expressed repertoire of SP-A protein in human airway has not been investigated. Here, we used parallel trypsin and Glu-C digestion, followed by LC-MS/MS, to obtain sequence coverage of common SP-A variants and isoform-determining peptides. We further developed a SDS-PAGE-based, multiple reaction monitoring (GeLC-MRM) assay for enrichment and targeted quantitation of total SP-A, the SP-A2 isoform, and the Gln223 and Lys223 variants of SP-A, from as little as one milliliter of bronchoalveolar lavage fluid. This assay identified individuals with the three genotypes at the 223 position of SP-A2: homozygous major (Gln223/Gln223), homozygous minor (Lys223/Lys223), or heterozygous (Gln223/Lys223). More generally, our studies demonstrate the challenges inherent in distinguishing highly homologous, copurifying protein isoforms by MS and show the applicability of MRM mass spectrometry for identification and quantitation of nonsynonymous single nucleotide variants and other proteoforms in airway lining fluid.
    Journal of Proteome Research 07/2014; · 5.06 Impact Factor
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    ABSTRACT: Diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) is a phosphorus-free betaine-lipid analog of phosphatidylcholine (PtdCho) synthesized by many soil bacteria, algae, and non-vascular plants. Synthesis of DGTS and other phosphorus-free lipids in bacteria occurs in response to phosphorus (P) deprivation, and results in the replacement of phospholipids by non-phosphorous lipids. The genes encoding DGTS biosynthetic enzymes have previously been identified and characterized in bacteria and the alga Chlamydomonas reinhardtii. We now report that many fungal genomes, including those of plant and animal pathogens, encode the enzymatic machinery for DGTS biosynthesis, and that fungi synthesize DGTS during P-limitation. This finding demonstrates that replacement of phospholipids by non-phosphorous lipids is a strategy used in divergent eukaryotic lineages for the conservation of P under P-limiting conditions. Mutants of Neurospora crassa were used to show that DGTS synthase encoded by the BTA1 gene is solely responsible for DGTS biosynthesis, and is under the control of the fungal phosphorus-deprivation regulon, mediated by the NUC-1/Pho4p transcription factor. Furthermore, we describe the rational re-engineering of lipid metabolism in the yeast S. cerevisiae such that PtdCho is completely replaced by DGTS, and demonstrate that essential processes of membrane biogenesis and organelle assembly are functional and support growth in the engineered strain.
    Eukaryotic Cell 04/2014; · 3.18 Impact Factor
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    ABSTRACT: Lysophospholipid acyltransferases (LPATs) incorporate fatty acyl chains into phospholipids via a coenzyme A (CoA)-dependent mechanism, and play an important role in controlling levels of free arachidonic acid (AA) and production of lipid mediators of inflammation. These enzymes use one lysophospholipid and one acyl-CoA ester as substrates. Traditional enzyme activity assays engage a single substrate pair, whereas in vivo multiple molecular species exist. A facile LPAT assay relevant to multiple substrates can provide a more realistic view of the regulation of arachidonic acid (AA) metabolism and phospholipid composition. Microsome preparations from RAW 264.7 cells were used to compare traditional LPAT assays, using individual lysophospholipids and AA-CoA, vs. a dual substrate choice assay using six different lysophospholipids and eight different acyl-CoA esters. The complex mixture of newly synthesized phospholipid products was analyzed using liquid chromatography coupled to tandem mass spectrometry. Both types of assays provided similar results, but the choice assay provided far more information relevant to multiple fatty acyl chain incorporation into various phospholipid classes. The dual choice assay was successfully used to validate engineered suppression of LPCAT3 activity in RAW 264.7 cells. These findings demonstrate that this assay provides much richer biochemical detail about the in vivo selectivity of LPATs.
    The Journal of Lipid Research 02/2014; · 4.73 Impact Factor
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    ABSTRACT: Toxoplasma gondii is a highly prevalent obligate intracellular parasite of the phylum Apicomplexa that also includes other parasites of clinical/veterinary importance, such as Plasmodium, Cryptosporidium and Eimeria. Acute infection by Toxoplasma is hallmarked by rapid proliferation in its host cells, and requires synthesis of parasite membranes. Phosphatidylethanolamine (PtdEtn) is the second major phospholipid class in T. gondii. Here, we reveal that PtdEtn is produced in the parasite mitochondrion and parasitophorous vacuole by decarboxylation of phosphatidylserine (PtdSer), and in the endoplasmic reticulum by fusion of CDP-ethanolamine and diacylglycerol. PtdEtn in the mitochondrion is synthesized by a PtdSer decarboxylase (TgPSD1mt) of the type I class. TgPSD1mt harbors a targeting peptide at its N-terminus that is required for the mitochondrial localization but not for the catalytic activity. Ablation of TgPSD1mt expression caused up to 45% impairment in the parasite growth. The PtdEtn content of the parasite mutant was unaffected however, suggesting the presence of compensatory mechanisms. Indeed, metabolic labeling revealed an increased usage of ethanolamine for PtdEtn synthesis by the mutant strain, and depletion of nutrient exacerbated the growth defect (~56%), which was partially restored by ethanolamine. Further, the survival and residual growth of the TgPSD1mt mutant in the nutrient-depleted medium indicated additional routes of PtdEtn biogenesis such as acquisition of host-derived lipid. Collectively, these results demonstrate a metabolic cooperativity between the parasite organelles, which ensures a sustained lipid synthesis, survival and growth of T. gondii in varying nutritional milieus.
    Journal of Biological Chemistry 01/2014; · 4.60 Impact Factor
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    ABSTRACT: Saccharomyces cerevisiae uses multiple biosynthetic pathways for the synthesis phosphatidylethanolamine (PtdEtn). One route involves the synthesis of phosphatidylserine (PtdSer) in the ER, the transport of this lipid to endosomes, and decarboxylation by PtdSer decarboxylase 2 (Psd2p) to produce PtdEtn. Several proteins and protein motifs are known to be required for PtdSer transport to occur, namely the Sec14p homolog PstB2p/Pdr17p; a PtdIns-4-kinase, Stt4p; and a C2 domain of Psd2p. The focus of this work is on defining the protein:protein and protein:lipid interactions of these components. PstB2p interacts with a protein encoded by the uncharacterized gene YPL272C, that we name Pbi1p (PstB2p interacting 1). PstB2p, Psd2, and Pbi1p were shown to be lipid-binding proteins specific for phosphatidic acid. Pbi1p also interacts with the ER localized Scs2p, a binding determinant for several peripheral ER proteins. A complex between Psd2p and PstB2p was also detected, and this interaction was facilitated by a cryptic C2 domain at the extreme N-terminus of Psd2p (C2-1), as well the previously characterized C2 domain of Psd2p (C2-2.) The predicted N-terminal helical region of PstB2p was necessary and sufficient for promoting the interaction with both Psd2p and Pbi1p. Taken together, these results support a model for PtdSer transport involving the docking of a PtdSer donor membrane with an acceptor via specific protein:protein and protein:lipid interactions. Specifically, our model predicts this process involves an acceptor membrane complex containing the C2 domains of Psd2p, PstB2p, and Pbi1p that ligate to Scs2p and phosphatidic acid present in the donor membrane, forming a zone of apposition that facilitates PtdSer transfer.
    Journal of Biological Chemistry 12/2013; 289(9). · 4.60 Impact Factor
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    ABSTRACT: Efficient transmission of Plasmodium species between humans and Anopheles mosquitoes is a major contributor to the global burden of malaria. Gametocytogenesis, the process by which parasites switch from asexual replication within human erythrocytes to produce male and female gametocytes, is a critical step in malaria transmission and Plasmodium genetic diversity. Nothing is known about the pathways that regulate gametocytogenesis and only few of the current drugs that inhibit asexual replication are also capable of inhibiting gametocyte development and blocking malaria transmission. Here we provide genetic and pharmacological evidence indicating that the pathway for synthesis of phosphatidylcholine in Plasmodium falciparum membranes from host serine is essential for parasite gametocytogenesis and malaria transmission. Parasites lacking the phosphoethanolamine N-methyltransferase enzyme, which catalyzes the limiting step in this pathway, are severely altered in gametocyte development, are incapable of producing mature-stage gametocytes, and are not transmitted to mosquitoes. Chemical screening identified 11 inhibitors of phosphoethanolamine N-methyltransferase that block parasite intraerythrocytic asexual replication and gametocyte differentiation in the low micromolar range. Kinetic studies in vitro as well as functional complementation assays and lipid metabolic analyses in vivo on the most promising inhibitor NSC-158011 further demonstrated the specificity of inhibition. These studies set the stage for further optimization of NSC-158011 for development of a class of dual activity antimalarials to block both intraerythrocytic asexual replication and gametocytogenesis.
    Proceedings of the National Academy of Sciences 10/2013; · 9.81 Impact Factor
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    ABSTRACT: Respiratory syncytial virus (RSV) causes respiratory tract infections in young children, and significant morbidity and mortality in the elderly, imunosuppressed and immunocompromised patients, and patients with chronic lung diseases. Recently, we reported the pulmonary surfactant phospholipid, palmitoyl-oleoyl-phosphatidylglycerol (POPG), inhibited RSV infection in vitro and in vivo, by blocking viral attachment to epithelial cells. Simultaneous application of POPG along with an RSV challenge to mice, markedly attenuated infection and associated inflammatory responses. Based on these findings, we expanded our studies to determine if POPG is effective for prophylaxis and post-infection treatment for RSV infection. In vitro application of POPG at concentrations of 0.2-1.0 mg/ml at 24hrs after RSV infection of HEp-2 cells, suppressed interleukin-8 production up to 80% and reduced viral plaque formation by 2-6 log units. In vivo, the turnover of POPG in mice is relatively rapid, making post-infection application impractical. Intranasal administration of POPG (0.8-3.0 mg), 45 min before RSV inoculation in mice, reduced viral infection by 1 log unit, suppressed inflammatory cell appearance in the lung, and suppressed virus elicited interferon-γ production. These findings demonstrate that POPG is effective for short-term protection of mice against subsequent RSV infection, and has potential for application in humans.
    The Journal of Lipid Research 06/2013; · 4.73 Impact Factor
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    ABSTRACT: Nuclear factor-kappa B (NFkB) is a ubiquitous transcription factor that mediates pro-inflammatory responses required for host control of many microbial pathogens; on the other hand, NFkB has been implicated in the pathogenesis of other inflammatory and infectious diseases. Mice with genetic disruption of the p50 subunit of NFkB are more likely to succumb to Mycobacterium tuberculosis (MTB). However, the role of NFkB in host defense in humans is not fully understood. We sought to examine the role of NFkB activation in the immune response of human macrophages to MTB. Targeted pharmacologic inhibition of NFkB activation using BAY 11-7082 (BAY, an inhibitor of IkBa kinase) or an adenovirus construct with a dominant-negative IkBa significantly decreased the number of viable intracellular mycobacteria recovered from THP-1 macrophages four and eight days after infection. The results with BAY were confirmed in primary human monocyte-derived macrophages and alveolar macrophages. NFkB inhibition was associated with increased macrophage apoptosis and autophagy, which are well-established killing mechanisms of intracellular MTB. Inhibition of the executioner protease caspase-3 or of the autophagic pathway significantly abrogated the effects of BAY. We conclude that NFkB inhibition decreases viability of intracellular MTB in human macrophages via induction of apoptosis and autophagy.
    PLoS ONE 04/2013; · 3.53 Impact Factor
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    ABSTRACT: There is increasing interest in the application of nanotechnology to solve the difficult problem of therapeutic administration of pharmaceuticals. Nanodiscs, composed of a stable discoidal lipid bilayer encircled by an amphipathic membrane scaffold protein that is an engineered variant of the human Apo A-I constituent of high-density lipoproteins, have been a successful platform for providing a controlled lipid composition in particles that are especially useful for investigating membrane protein structure and function. In this communication, we demonstrate that nanodiscs are effective in suppressing respiratory syncytial viral (RSV) infection both in vitro and in vivo when self-assembled with the minor pulmonary surfactant phospholipid palmitoyloleoylphosphatidylglycerol (POPG). Preparations of nanodiscs containing POPG (nPOPG) antagonized interleukin-8 production from Beas2B epithelial cells challenged by RSV infection, with an IC50 of 19.3 μg/mL. In quantitative in vitro plaque assays, nPOPG reduced RSV infection by 93%. In vivo, nPOPG suppressed inflammatory cell infiltration into the lung, as well as IFN-γ production in response to RSV challenge. nPOPG also completely suppressed the histopathological changes in lung tissue elicited by RSV and reduced the amount of virus recovered from lung tissue by 96%. The turnover rate of nPOPG was estimated to have a halftime of 60-120 minutes (m), based upon quantification of the recovery of the human Apo A-I constituent. From these data, we conclude that nPOPG is a potent antagonist of RSV infection and its inflammatory sequelae both in vitro and in vivo.
    International Journal of Nanomedicine 04/2013; 8:1417-1427. · 4.20 Impact Factor
    This article is viewable in ResearchGate's enriched format
  • Mari Numata, Pitchaimani Kandasamy, Dennis R Voelker
    Expert Review of Respiratory Medicine 06/2012; 6(3):243-6.
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    ABSTRACT: Toxoplasma gondii is an obligate intracellular parasite capable of causing fatal infections in immunocompromised individuals and neonates. Examination of the phosphatidylserine (PtdSer) metabolism of T. gondii reveals that the parasite secretes a soluble form of PtdSer decarboxylase (TgPSD1), which preferentially decarboxylates liposomal PtdSer with an apparent K(m) of 67 μM. The specific enzyme activity increases by 3-fold during the replication of T. gondii, and soluble phosphatidylserine decarboxylase (PSD) accounts for ∼20% of the total PSD, prior to the parasite egress from the host cells. Extracellular T. gondii secreted ∼20% of its total PSD activity at 37 °C, and the intracellular Ca(2+) chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis (acetoxymethyl ester) inhibited the process by 50%. Cycloheximide, brefeldin A, ionic composition of the medium, and exogenous PtdSer did not modulate the enzyme secretion, which suggests a constitutive discharge of a presynthesized pool of PSD in axenic T. gondii. TgPSD1 consists of 968 amino acids with a 26-amino acid hydrophobic peptide at the N terminus and no predicted membrane domains. Parasites overexpressing TgPSD1-HA secreted 10-fold more activity compared with the parental strain. Exposure of apoptotic Jurkat cells to transgenic parasites demonstrated interfacial catalysis by secreted TgPSD1 that reduced host cell surface exposure of PtdSer. Immunolocalization experiments revealed that TgPSD1 resides in the dense granules of T. gondii and is also found in the parasitophorous vacuole of replicating parasites. Together, these findings demonstrate novel features of the parasite enzyme because a secreted, soluble, and interfacially active form of PSD has not been previously described for any organism.
    Journal of Biological Chemistry 05/2012; 287(27):22938-47. · 4.60 Impact Factor
  • American Thoracic Society 2012 International Conference, May 18-23, 2012 • San Francisco, California; 05/2012
  • American Thoracic Society 2012 International Conference, May 18-23, 2012 • San Francisco, California; 05/2012
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    ABSTRACT: Signal regulatory protein α (SIRPα), a highly glycosylated type-1 transmembrane protein, is composed of three immunoglobulin-like extracellular loops as well as a cytoplasmic tail containing three classical tyrosine-based inhibitory motifs. Previous reports indicate that SIRPα binds to humoral pattern recognition molecules in the collectin family, namely surfactant proteins D and A (Sp-D and Sp-A, respectively), which are heavily expressed in the lung and constitute one of the first lines of innate immune defense against pathogens. However, little is known about molecular details of the structural interaction of Sp-D with SIRPs. In the present work, we examined the molecular basis of Sp-D binding to SIRPα using domain-deleted mutant proteins. We report that Sp-D binds to the membrane-proximal Ig domain (D3) of SIRPα in a calcium- and carbohydrate-dependent manner. Mutation of predicted N-glycosylation sites on SIRPα indicates that Sp-D binding is dependent on interactions with specific N-glycosylated residues on the membrane-proximal D3 domain of SIRPα. Given the remarkable sequence similarity of SIRPα to SIRPβ and the lack of known ligands for the latter, we examined Sp-D binding to SIRPβ. Here, we report specific binding of Sp-D to the membrane-proximal D3 domain of SIRPβ. Further studies confirmed that Sp-D binds to SIRPα expressed on human neutrophils and differentiated neutrophil-like cells. Because the other known ligand of SIRPα, CD47, binds to the membrane-distal domain D1, these findings indicate that multiple, distinct, functional ligand binding sites are present on SIRPα that may afford differential regulation of receptor function.
    Journal of Biological Chemistry 04/2012; 287(23):19386-98. · 4.60 Impact Factor
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    ABSTRACT: In yeast, a protein complex termed the ER-Mitochondria Encounter Structure (ERMES) tethers mitochondria to the endoplasmic reticulum. ERMES proteins are implicated in a variety of cellular functions including phospholipid synthesis, mitochondrial protein import, mitochondrial attachment to actin, polarized mitochondrial movement into daughter cells during division, and maintenance of mitochondrial DNA (mtDNA). The mitochondrial-anchored Gem1 GTPase has been proposed to regulate ERMES functions. Here, we show that ERMES and Gem1 have no direct role in the transport of phosphatidylserine (PS) from the ER to mitochondria during the synthesis of phosphatidylethanolamine (PE), as PS to PE conversion is not affected in ERMES or gem1 mutants. In addition, we report that mitochondrial inheritance defects in ERMES mutants are a secondary consequence of mitochondrial morphology defects, arguing against a primary role for ERMES in mitochondrial association with actin and mitochondrial movement. Finally, we show that ERMES complexes are long-lived, and do not depend on the presence of Gem1. Our findings suggest that the ERMES complex may have primarily a structural role in maintaining mitochondrial morphology.
    Traffic 03/2012; 13(6):880-90. · 4.71 Impact Factor

Publication Stats

7k Citations
878.60 Total Impact Points

Institutions

  • 2013
    • United States Department of Veterans Affairs
      Бедфорд, Massachusetts, United States
  • 2009–2013
    • National Jewish Health
      • Department of Medicine
      Denver, Colorado, United States
  • 2012
    • Humboldt-Universität zu Berlin
      Berlín, Berlin, Germany
  • 2011
    • Colorado State University
      • Microbiology, Immunology & Pathology
      Fort Collins, CO, United States
  • 2009–2011
    • Duke University Medical Center
      Durham, North Carolina, United States
  • 2005–2008
    • Kanazawa Medical University
      • Department of Respiratory Medicine
      Kanazawa-shi, Ishikawa-ken, Japan
  • 1994–2008
    • Sapporo Medical University
      • Department of Biochemistry
      Sapporo, Hokkaidō, Japan
  • 2007
    • The Ohio State University
      • Division of Infectious Diseases
      Columbus, Ohio, United States
  • 2003
    • University of Florida
      • Department of Horticultural Sciences
      Gainesville, Florida, United States
  • 2002
    • University of Iowa
      • Division of Pulmonary, Critical Care, and Occupational Medicine
      Iowa City, Iowa, United States
  • 2001
    • National Research Center (CO, USA)
      Boulder, Colorado, United States
    • Moredun Research Institute
      Penicuik, Scotland, United Kingdom
  • 1998–1999
    • Rutgers, The State University of New Jersey
      • New Jersey Agricultural Experiment Station
      New Brunswick, NJ, United States
    • University of Texas at Austin
      • Institute for Cellular and Molecular Biology
      Texas City, TX, United States
  • 1996
    • U.S. Department of Veterans Affairs
      Washington, Washington, D.C., United States
    • Emory University
      • Department of Chemistry
      Atlanta, Georgia, United States