1
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Serrapeptase impairs biofilm, wall, and phospho-homeostasis of resistant and susceptible Staphylococcus aureus. Appl Microbiol Biotechnol 2023; 107:1373-1389. [PMID: 36635396 PMCID: PMC9898353 DOI: 10.1007/s00253-022-12356-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 11/25/2022] [Accepted: 12/22/2022] [Indexed: 01/14/2023]
Abstract
Staphylococcus aureus biofilms are implicated in hospital infections due to elevated antibiotic and host immune system resistance. Molecular components of cell wall including amyloid proteins, peptidoglycans (PGs), and lipoteichoic acid (LTA) are crucial for biofilm formation and tolerance of methicillin-resistant S. aureus (MRSA). Significance of alkaline phosphatases (ALPs) for biofilm formation has been recorded. Serrapeptase (SPT), a protease of Serratia marcescens, possesses antimicrobial properties similar or superior to those of many antibiotics. In the present study, SPT anti-biofilm activity was demonstrated against S. aureus (ATCC 25923, methicillin-susceptible strain, methicillin-susceptible S. aureus (MSSA)) and MRSA (ST80), with IC50 values of 0.67 μg/mL and 7.70 μg/mL, respectively. SPT affected bacterial viability, causing a maximum inhibition of - 46% and - 27%, respectively. Decreased PGs content at [SPT] ≥ 0.5 μg/mL and ≥ 8 μg/mL was verified for MSSA and MRSA, respectively. In MSSA, LTA levels decreased significantly (up to - 40%) at lower SPT doses but increased at the highest dose of 2 μg/mL, a counter to spectacularly increased cellular and secreted LTA levels in MRSA. SPT also reduced amyloids of both strains. Additionally, intracellular ALP activity decreased in both MSSA and MRSA (up to - 85% and - 89%, respectively), while extracellular activity increased up to + 482% in MSSA and + 267% in MRSA. Altered levels of DING proteins, which are involved in phosphate metabolism, in SPT-treated bacteria, were also demonstrated here, implying impaired phosphorus homeostasis. The differential alterations in the studied molecular aspects underline the differences between MSSA and MRSA and offer new insights in the treatment of resistant bacterial biofilms. KEY POINTS: • SPT inhibits biofilm formation in methicillin-resistant and methicillin-susceptible S. aureus. • SPT treatment decreases bacterial viability, ALP activity, and cell wall composition. • SPT-treated bacteria present altered levels of phosphate-related DING proteins.
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2
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Zhang X, Yin Z, Ma Z, Liang J, Zhang Z, Yao L, Chen X, Liu X, Zhang R. Shell Matrix Protein N38 of Pinctada fucata, Inducing Vaterite Formation, Extends the DING Protein to the Mollusca World. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2022; 24:531-541. [PMID: 35499596 DOI: 10.1007/s10126-022-10116-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 03/11/2022] [Indexed: 06/14/2023]
Abstract
In the animal kingdom, DING proteins were only found in Chordata and Aschelminthes. At present study, a potential DING protein, matrix protein N38, was isolated and purified from the shell of Pinctada fucata. Tandem mass spectrometry analysis revealed that 14 peptide segments matched between N38 and human phosphate-binding protein (HPBP). HPBP belongs to the DING protein family and has a "DINGGG-" sequence, which is considered a "signature" of HPBP. In this study, the mass spectrometry analysis results showed that N38 had a "DIDGGG-" sequence; this structure is a mutation from the "DINGGG-" structure, which is a distinctive feature of the DING protein family. The role of N38 during calcium carbonate formation was explored through the in vitro crystallization experiment. The results of scanning electron microscopy and Raman spectrum analysis indicated that N38 induced vaterite formation. These findings revealed that N38 might regulate and participate in the precise control of the crystal growth of the shell, providing new clues for biomineralization mechanisms in P. fucata and DING protein family studies. In addition, this study helped extend the research of DING protein to the Mollusca world.
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Affiliation(s)
- Xin Zhang
- Key Laboratory of Freshwater Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Agriculture, Shanghai, 201306, China
| | - Zehui Yin
- Key Laboratory of Freshwater Aquatic Genetic Resources, Shanghai Ocean University, Ministry of Agriculture, Shanghai, 201306, China
| | - Zhuojun Ma
- Chinese Academy of Fishery Sciences, Beijing, 100141, China
| | - Jian Liang
- State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining, 810016, China
| | - Zhen Zhang
- Department of Biotechnology and Biomedicine, Yangtze Delta Region Institute of Tsinghua University, Zhejiang, 314000, China
| | - Liping Yao
- Department of Biotechnology and Biomedicine, Yangtze Delta Region Institute of Tsinghua University, Zhejiang, 314000, China
| | - Xia Chen
- Department of Biotechnology and Biomedicine, Yangtze Delta Region Institute of Tsinghua University, Zhejiang, 314000, China
| | - Xiaojun Liu
- Department of Biotechnology and Biomedicine, Yangtze Delta Region Institute of Tsinghua University, Zhejiang, 314000, China.
| | - Rongqing Zhang
- Protein Science laboratory of the Ministry of Education, Tsinghua University, Beijing, 100084, China.
- Department of Biotechnology and Biomedicine, Yangtze Delta Region Institute of Tsinghua University, Zhejiang, 314000, China.
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3
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Bizic M, Ionescu D, Karnatak R, Musseau CL, Onandia G, Berger SA, Nejstgaard JC, Lischeid G, Gessner MO, Wollrab S, Grossart HP. Land-use type temporarily affects active pond community structure but not gene expression patterns. Mol Ecol 2022; 31:1716-1734. [PMID: 35028982 DOI: 10.1111/mec.16348] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/30/2021] [Accepted: 01/04/2022] [Indexed: 11/30/2022]
Abstract
Changes in land use and agricultural intensification threaten biodiversity and ecosystem functioning of small water bodies. We studied 67 kettle holes (KH) in an agricultural landscape in northeastern Germany using landscape-scale metatranscriptomics, to understand the responses of active bacterial, archaeal, and eukaryotic communities, to land-use type. These KH are proxies of the millions of small standing water bodies of glacial origin spread across the northern hemisphere. Like other landscapes in Europe, the study area has been used for intensive agriculture since the 1950s. In contrast to a parallel eDNA study which revealed the homogenization of biodiversity across KH conceivably resulting from long-lasting intensive agriculture, land-use type affected the structure of the active KH communities during spring crop fertilization, but not a month later. This effect was more pronounced in eukaryotes than in bacteria. In contrast, gene expression patterns did not differ between months or across land-use type, suggesting a high degree of functional redundancy across the KH communities. Variability in gene expression was best explained by active bacterial and eukaryotic community structures, suggesting that these changes in functioning are primarily driven by interactions between organisms. Our results show that influences of the surrounding landscape result in temporary changes in the activity of different community members. Thus, even in KH where biodiversity has been homogenized, communities continue to respond to land management. This needs to be considered when developing sustainable management options for restoration purposes and for successful mitigation of further biodiversity loss in agricultural landscapes.
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Affiliation(s)
- M Bizic
- Departments of Experimental Limnology and Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin and Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - D Ionescu
- Departments of Experimental Limnology and Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin and Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - R Karnatak
- Departments of Experimental Limnology and Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin and Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - C L Musseau
- Departments of Experimental Limnology and Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin and Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany.,Department of Biology, Chemistry, Pharmacy, Institute of Biology, Free University of Berlin, Berlin, Germany
| | - G Onandia
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany.,Research Platform Data Analysis and Simulation, Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany
| | - S A Berger
- Departments of Experimental Limnology and Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin and Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - J C Nejstgaard
- Departments of Experimental Limnology and Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin and Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - G Lischeid
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany.,Research Platform Data Analysis and Simulation, Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany.,Institute for Environmental Sciences and Geography, Potsdam University, Potsdam, Germany
| | - M O Gessner
- Departments of Experimental Limnology and Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin and Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany.,Department of Ecology, Berlin Institute of Technology (TU Berlin), Berlin, Germany
| | - S Wollrab
- Departments of Experimental Limnology and Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin and Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany
| | - H-P Grossart
- Departments of Experimental Limnology and Ecosystem Research, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin and Berlin, Germany.,Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), Berlin, Germany.,Institute of Biochemistry and Biology, Potsdam University, Potsdam, Germany
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4
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Porzio E, Faraone Mennella MR, Manco G. DING Proteins Extend to the Extremophilic World. Int J Mol Sci 2021; 22:2035. [PMID: 33670786 PMCID: PMC7922408 DOI: 10.3390/ijms22042035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/04/2021] [Accepted: 02/16/2021] [Indexed: 11/16/2022] Open
Abstract
The DING proteins are ubiquitous in the three domains of life, from mesophiles to thermo- and hyperthermophiles. They belong to a family of more than sixty members and have a characteristic N-terminus, DINGGG, which is considered a "signature" of these proteins. Structurally, they share a highly conserved phosphate binding site, and a three dimensional organization resembling the "Venus Flytrap", both reminding the ones of PstS proteins. They have unusually high sequence conservation, even between distantly related species. Nevertheless despite that the genomes of most of these species have been sequenced, the DING gene has not been reported for all the relative characterized DING proteins. Identity of known DING proteins has been confirmed immunologically and, in some cases, by N-terminal sequence analysis. Only a few of the DING proteins have been purified and biochemically characterized. DING proteins are heterogeneous for their wide range of biological activities and some show different activities not always correlated with each other. Most of them have been originally identified for different biological properties, or rather for binding to phosphate and also to other ligands. Their involvement in pathologies is described. This review is an update of the most recent findings on old and new DING proteins.
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Affiliation(s)
- Elena Porzio
- Institute of Biochemistry and Cell Biology, CNR, Via P. Castellino 111, 80131 Naples, Italy;
| | | | - Giuseppe Manco
- Institute of Biochemistry and Cell Biology, CNR, Via P. Castellino 111, 80131 Naples, Italy;
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5
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Aleshin VA, Mezhenska OA, Parkhomenko YM, Kaehne T, Bunik VI. Thiamine Mono- and Diphosphate Phosphatases in Bovine Brain Synaptosomes. BIOCHEMISTRY (MOSCOW) 2021; 85:378-386. [PMID: 32564742 DOI: 10.1134/s000629792003013x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Neurodegenerative diseases are accompanied by changes in the activity of thiamine mono- and diphosphate phosphatases, but molecular identification of these mammalian enzymes is incomplete. In this work, the protein fraction of bovine brain synaptosomes displaying phosphatase activity toward thiamine derivatives was subjected to affinity chromatography on thiamine-Sepharose. Protein fractions eluted with thiamine (pH 7.4 or 5.6), NaCl, and urea were assayed for the phosphatase activity against thiamine monophosphate (ThMP), thiamine diphosphate (ThDP), and structurally similar purine nucleotides. Proteins in each fraction were identified by mass spectrometry using the SwissProt database for all organisms because of insufficient annotation of the bovine genome. Peptides of two annotated bacterial phosphatases, alkaline phosphatase L from the DING protein family and exopolyphosphatase, were identified in the acidic thiamine eluate. The abundance of peptides of alkaline phosphatase L and exopolyphosphatase in the eluted fractions correlated with ThMPase and ThDPase activities, respectively. The elution profiles of the ThMPase and ThDPase activities differed from the elution profiles of nucleotide phosphatases, thus indicating the specificity of these enzymes toward thiamine derivatives. The search for mammalian DING phosphatases in the eluates from thiamine-Sepharose revealed X-DING-CD4, mostly eluted by the acidic thiamine solution (pH 5.6). The identified exopolyphosphatase demonstrated structural similarity with apyrases possessing the ThDPase activity. The obtained results demonstrate that mammalian DING proteins and apyrases exhibit ThMPase and ThDPase activity, respectively.
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Affiliation(s)
- V A Aleshin
- Lomonosov Moscow State University, Faculty of Bioengineering and Bioinformatics, Moscow, 119991, Russia. .,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - O A Mezhenska
- Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv, 01601, Ukraine
| | - Y M Parkhomenko
- Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv, 01601, Ukraine
| | - T Kaehne
- Institute of Experimental Internal Medicine, Otto von Guericke University, Magdeburg, 39120, Germany
| | - V I Bunik
- Lomonosov Moscow State University, Faculty of Bioengineering and Bioinformatics, Moscow, 119991, Russia. .,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.,Sechenov First Moscow State Medical University, Ministry of Health of the Russian Federation, Moscow, 119992, Russia
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6
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Darbinian N, Darbinyan A, Merabova N, Gomberg R, Chabriere E, Simm M, Selzer ME, Amini S. DING Protein Inhibits Transcription of HIV-1 Gene through Suppression of Phosphorylation of NF-κB p65. ACTA ACUST UNITED AC 2020; 6. [PMID: 34307877 PMCID: PMC8296972 DOI: 10.16966/2380-5536.175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Introduction: Novel plant DING proteins (full-length 38 kDa p38SJ, and 27 kDa p27SJ) exhibit phosphatase activity and modulate HIV-1 gene transcription. Previously, we demonstrated that DING regulates HIV-1 gene transcription by dephosphorylation and inactivation of CTD RNA polymerase II, the major elongating factor of HIV-1 Long Terminal Repeats (LTR). Because the transcription of HIV-1 is controlled by several viral and cellular factors, including p65/p50 subunits of NF-κB, we hypothesized that DING phosphatase can also affect the phosphorylation and activity of p65 NF-κB, in addition to C-terminal Domain (CTD) of RNA Polymerase II (RNAPII), to suppress HIV-1 gene transcription and inhibit HIV-1 infection. Methods: Here, we describe the inhibition of HIV-1 infection and the p65/p50 NF-κB phosphorylation by DING protein, analyzed by ELISA and northern-blot assays, western-blot assays, cell fractionation, and promoter-reporter assays in DING-expressing cells, using a pTet-on inducible system. Results: Results from HIV-1 infection assays demonstrate a strong inhibition of HIV-1 and HIV-LTR RNA expression by DING protein, determined by p24 ELISA and by northern blot assay. Results from the western blot assays and cell fractionation assays show that there is an increase in the level of hypo-phosphorylated form of p65 NF-κB in DING-expressing cells. Both fractions of p65/p50, nuclear or cytoplasmic, are affected by DING phosphatase, but more cytoplasmic accumulation of p65 NF-κB was found in the presence of DING, suggesting that subsequent activation and nuclear import of active NF-κB is affected by DING. The major portion of nuclear p65 was dephosphorylated in DING-expressing cells. The promoter-reporter assay demonstrated that DING-mediated dephosphorylation and dysregulation of NF-κB p65 lead to the suppression of its binding to HIV-1 LTR, and resulted in the inhibition of p65-mediated activation of LTR transcription. Mapping of the region within LTR that was affected by DING revealed that both, NF-κB and CTD RNA Polymerase II binding sites were important, and cooperativity of these cellular factors was diminished by DING. In addition, mapping of the region within DING-p38SJ that affected LTR transcription, revealed that phosphate-binding domain is essential for this inhibitory activity. Conclusion: We have demonstrated the effect of DING phosphatases on HIV-1 infection, phosphorylation of p65 NF-κB, and transcription of HIV-1 LTR. Our studies suggest that one possible mechanism by which DING can regulate the expression of HIV-1 LTR can be through dysregulation of the transcription factor NF-κB p65 by preventing its phosphorylation and translocation to the nucleus and binding to the HIV-1 LTR, an action that could contribute to the utility of DING p38SJ as an antiviral agent. Importantly, DING not only inhibits HIV-1 LTR gene transcription in the presence of increased p65 NF-κB, but also suppresses HIV-1 infection. DING protein improved inhibitory effects of the known anti-retroviral drugs, Tenofovir (TFV) and Emtricitabine (FTS) on HIV-1, since in the combination with these drugs; the suppression of HIV-1 by DNG was significantly higher when it was in combination with these drugs, compared to controls or cases without DING. Thus, our data support the use of neuroprotective DING proteins as novel therapeutic antiviral drugs that suppress HIV-1 LTR transcription by interfering with the function of NF-κB.
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Affiliation(s)
- Nune Darbinian
- Center for Neural Repair and Rehabilitation, Lewis Katz School of Medicine, Temple University, USA
| | - Armine Darbinyan
- Department of Pathology, Yale University School of Medicine, USA
| | - Nana Merabova
- Center for Neural Repair and Rehabilitation, Lewis Katz School of Medicine, Temple University, USA
| | - Rebeccah Gomberg
- Center for Neural Repair and Rehabilitation, Lewis Katz School of Medicine, Temple University, USA
| | - Erik Chabriere
- Aix-Marseille Université, Institut Universitaire de France, IHU Mediterranée Infection, France
| | - Malgorzata Simm
- University of Pikeville, Kentucky College of Osteopathic Medicine, USA
| | - Michael E Selzer
- Center for Neural Repair and Rehabilitation, Lewis Katz School of Medicine, Temple University, USA
| | - Shohreh Amini
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, USA
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7
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Abstract
Phosphate is an essential nutrient for life and is a critical component of bone formation, a major signaling molecule, and structural component of cell walls. Phosphate is also a component of high-energy compounds (i.e., AMP, ADP, and ATP) and essential for nucleic acid helical structure (i.e., RNA and DNA). Phosphate plays a central role in the process of mineralization, normal serum levels being associated with appropriate bone mineralization, while high and low serum levels are associated with soft tissue calcification. The serum concentration of phosphate and the total body content of phosphate are highly regulated, a process that is accomplished by the coordinated effort of two families of sodium-dependent transporter proteins. The three isoforms of the SLC34 family (SLC34A1-A3) show very restricted tissue expression and regulate intestinal absorption and renal excretion of phosphate. SLC34A2 also regulates the phosphate concentration in multiple lumen fluids including milk, saliva, pancreatic fluid, and surfactant. Both isoforms of the SLC20 family exhibit ubiquitous expression (with some variation as to which one or both are expressed), are regulated by ambient phosphate, and likely serve the phosphate needs of the individual cell. These proteins exhibit similarities to phosphate transporters in nonmammalian organisms. The proteins are nonredundant as mutations in each yield unique clinical presentations. Further research is essential to understand the function, regulation, and coordination of the various phosphate transporters, both the ones described in this review and the phosphate transporters involved in intracellular transport.
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Affiliation(s)
- Nati Hernando
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Kenneth Gagnon
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
| | - Eleanor Lederer
- University of Zurich-Irchel, Institute of Physiology, Zurich, Switzerland; Department of Medicine, University of Louisville School of Medicine, Louisville, Kentucky; and Robley Rex VA Medical Center, Louisville, Kentucky
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8
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Mishra SK, Gao YG, Zou X, Stephenson DJ, Malinina L, Hinchcliffe EH, Chalfant CE, Brown RE. Emerging roles for human glycolipid transfer protein superfamily members in the regulation of autophagy, inflammation, and cell death. Prog Lipid Res 2020; 78:101031. [PMID: 32339554 DOI: 10.1016/j.plipres.2020.101031] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 02/27/2020] [Accepted: 02/27/2020] [Indexed: 12/14/2022]
Abstract
Glycolipid transfer proteins (GLTPs) were first identified over three decades ago as ~24kDa, soluble, amphitropic proteins that specifically accelerate the intermembrane transfer of glycolipids. Upon discovery that GLTPs use a unique, all-α-helical, two-layer 'sandwich' architecture (GLTP-fold) to bind glycosphingolipids (GSLs), a new protein superfamily was born. Structure/function studies have provided exquisite insights defining features responsible for lipid headgroup selectivity and hydrophobic 'pocket' adaptability for accommodating hydrocarbon chains of differing length and unsaturation. In humans, evolutionarily-modified GLTP-folds have been identified with altered sphingolipid specificity, e. g. ceramide-1-phosphate transfer protein (CPTP), phosphatidylinositol 4-phosphate adaptor protein-2 (FAPP2) which harbors a GLTP-domain and GLTPD2. Despite the wealth of structural data (>40 Protein Data Bank deposits), insights into the in vivo functional roles of GLTP superfamily members have emerged slowly. In this review, recent advances are presented and discussed implicating human GLTP superfamily members as important regulators of: i) pro-inflammatory eicosanoid production associated with Group-IV cytoplasmic phospholipase A2; ii) autophagy and inflammasome assembly that drive surveillance cell release of interleukin-1β and interleukin-18 inflammatory cytokines; iii) cell cycle arrest and necroptosis induction in certain colon cancer cell lines. The effects exerted by GLTP superfamily members appear linked to their ability to regulate sphingolipid homeostasis by acting in either transporter and/or sensor capacities. These timely findings are opening new avenues for future cross-disciplinary, translational medical research involving GLTP-fold proteins in human health and disease. Such avenues include targeted regulation of specific GLTP superfamily members to alter sphingolipid levels as a therapeutic means for combating viral infection, neurodegenerative conditions and circumventing chemo-resistance during cancer treatment.
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Affiliation(s)
- Shrawan K Mishra
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Yong-Guang Gao
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Xianqiong Zou
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Daniel J Stephenson
- Department of Biochemistry and Molecular Biology, Virginia Commonwealth University Medical Center, Richmond, VA 23298-0614, USA; Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, USA
| | - Lucy Malinina
- Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | | | - Charles E Chalfant
- Department of Cell Biology, Microbiology and Molecular Biology, University of South Florida, Tampa, FL 33620, USA; Research Service, James A. Haley Veterans Hospital, Tampa, FL 33612, USA; The Moffitt Cancer Center, Tampa, FL 33620, USA
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9
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Brito-Argáez L, Tamayo-Sansores JA, Madera-Piña D, García-Villalobos FJ, Moo-Puc RE, Kú-González Á, Villanueva MA, Islas-Flores I. Biochemical characterization and immunolocalization studies of a Capsicum chinense Jacq. protein fraction containing DING proteins and anti-microbial activity. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2016; 109:502-514. [PMID: 27835848 DOI: 10.1016/j.plaphy.2016.10.031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 10/24/2016] [Accepted: 10/25/2016] [Indexed: 06/06/2023]
Abstract
The DING protein family consists of proteins of great biological importance due to their ability to inhibit carcinogenic cell growth. A DING peptide with Mr ∼7.57 kDa and pI ∼5.06 was detected in G10P1.7.57, a protein fraction from Capsicum chinense Jacq. seeds. Amino acid sequencing of the peptide produced three smaller peptides showing identity to the DING protein family. G10P1.7.57 displayed a phosphatase activity capable of dephosphorylating different phosphorylated substrates and inhibited the growth of Saccharomyces cerevisiae cells. Western immunoblotting with a custom-made polyclonal antibody raised against a sequence (ITYMSPDYAAPTLAGLDDATK), derived from the ∼7.57 kDa polypeptide, immunodetected an ∼ 39 kDa polypeptide in G10P1.7.57. Purification by electroelution followed by amino acid sequencing of the ∼39 kDa polypeptide yielded seven new peptide sequences and an additional one identical to that of the initially identified peptide. Western immunoblotting of soluble proteins from C. chinense seeds and leaves revealed the presence of the ∼39 kDa polypeptide at all developmental stages, with increased accumulation when the organs reached maturity. Immunolocalization using Dabsyl chloride- or Alexa fluor 488-conjugated antibodies revealed a specific fluorescent signal in the cell cytoplasm at all developmental stages, giving support to the idea that the ∼39 kDa polypeptide is a soluble DING protein. Thus, we have identified and characterized a protein fraction with a DING protein from C. chinense.
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Affiliation(s)
- Ligia Brito-Argáez
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán A.C., Calle 43 No. 130, Colonia Chuburná de Hidalgo, C.P. 97200, Mérida, Yucatán, Mexico
| | - José A Tamayo-Sansores
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán A.C., Calle 43 No. 130, Colonia Chuburná de Hidalgo, C.P. 97200, Mérida, Yucatán, Mexico
| | - Dianeli Madera-Piña
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán A.C., Calle 43 No. 130, Colonia Chuburná de Hidalgo, C.P. 97200, Mérida, Yucatán, Mexico
| | - Francisco J García-Villalobos
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán A.C., Calle 43 No. 130, Colonia Chuburná de Hidalgo, C.P. 97200, Mérida, Yucatán, Mexico
| | - Rosa E Moo-Puc
- Unidad de Investigación, Instituto Mexicano del Seguro Social, IMSS, T1, C.P. 97150, Mérida, Yucatán, Mexico
| | - Ángela Kú-González
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán A.C., Calle 43 No. 130, Colonia Chuburná de Hidalgo, C.P. 97200, Mérida, Yucatán, Mexico
| | - Marco A Villanueva
- Unidad Académica de Sistemas Arrecifales, Instituto de Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Puerto Morelos, Quintana Roo, C.P. 77580, Mexico
| | - Ignacio Islas-Flores
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán A.C., Calle 43 No. 130, Colonia Chuburná de Hidalgo, C.P. 97200, Mérida, Yucatán, Mexico.
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10
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Lidbury IDEA, Murphy ARJ, Scanlan DJ, Bending GD, Jones AME, Moore JD, Goodall A, Hammond JP, Wellington EMH. Comparative genomic, proteomic and exoproteomic analyses of three Pseudomonas strains reveals novel insights into the phosphorus scavenging capabilities of soil bacteria. Environ Microbiol 2016; 18:3535-3549. [PMID: 27233093 PMCID: PMC5082522 DOI: 10.1111/1462-2920.13390] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bacteria that inhabit the rhizosphere of agricultural crops can have a beneficial effect on crop growth. One such mechanism is the microbial-driven solubilization and remineralization of complex forms of phosphorus (P). It is known that bacteria secrete various phosphatases in response to low P conditions. However, our understanding of their global proteomic response to P stress is limited. Here, exoproteomic analysis of Pseudomonas putida BIRD-1 (BIRD-1), Pseudomonas fluorescens SBW25 and Pseudomonas stutzeri DSM4166 was performed in unison with whole-cell proteomic analysis of BIRD-1 grown under phosphate (Pi) replete and Pi deplete conditions. Comparative exoproteomics revealed marked heterogeneity in the exoproteomes of each Pseudomonas strain in response to Pi depletion. In addition to well-characterized members of the PHO regulon such as alkaline phosphatases, several proteins, previously not associated with the response to Pi depletion, were also identified. These included putative nucleases, phosphotriesterases, putative phosphonate transporters and outer membrane proteins. Moreover, in BIRD-1, mutagenesis of the master regulator, phoBR, led us to confirm the addition of several novel PHO-dependent proteins. Our data expands knowledge of the Pseudomonas PHO regulon, including species that are frequently used as bioinoculants, opening up the potential for more efficient and complete use of soil complexed P.
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Affiliation(s)
- Ian D E A Lidbury
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, West Midlands, CV4 7AL, UK.
| | - Andrew R J Murphy
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, West Midlands, CV4 7AL, UK
| | - David J Scanlan
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, West Midlands, CV4 7AL, UK
| | - Gary D Bending
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, West Midlands, CV4 7AL, UK
| | - Alexandra M E Jones
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, West Midlands, CV4 7AL, UK
| | - Jonathan D Moore
- The Genome Analysis Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Andrew Goodall
- School of Agriculture, Policy, and Development, University of Reading, Earley Gate, Whiteknights, Reading, RG6 6AR, UK
| | - John P Hammond
- School of Agriculture, Policy, and Development, University of Reading, Earley Gate, Whiteknights, Reading, RG6 6AR, UK
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW 2480, Australia
| | - Elizabeth M H Wellington
- School of Life Sciences, University of Warwick, Gibbet Hill Road, Coventry, West Midlands, CV4 7AL, UK
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11
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Le Douce V, Ait-Amar A, Forouzan Far F, Fahmi F, Quiel J, El Mekdad H, Daouad F, Marban C, Rohr O, Schwartz C. Improving combination antiretroviral therapy by targeting HIV-1 gene transcription. Expert Opin Ther Targets 2016; 20:1311-1324. [PMID: 27266557 DOI: 10.1080/14728222.2016.1198777] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
INTRODUCTION Combination Antiretroviral Therapy (cART) has not allowed the cure of HIV. The main obstacle to HIV eradication is the existence of quiescent reservoirs. Several other limitations of cART have been described, such as strict life-long treatment and high costs, restricting it to Western countries, as well as the development of multidrug resistance. Given these limitations and the impetus to find a cure, the development of new treatments is necessary. Areas covered: In this review, we discuss the current status of several efficient molecules able to suppress HIV gene transcription, including NF-kB and Tat inhibitors. We also assess the potential of new proteins belonging to the intriguing DING family, which have been reported to have potential anti-HIV-1 activity by inhibiting HIV gene transcription. Expert opinion: Targeting HIV-1 gene transcription is an alternative approach, which could overcome cART-related issues, such as the emergence of multidrug resistance. Improving cART will rely on the identification and characterization of new actors inhibiting HIV-1 transcription. Combining such efforts with the use of new technologies, the development of new models for preclinical studies, and improvement in drug delivery will considerably reduce drug toxicity and thus increase patient adherence.
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Affiliation(s)
- Valentin Le Douce
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France.,b IUT de Schiltigheim , Schiltigheim , France.,c UCD Centre for Research in Infectious Diseases (CRID) School of Medicine and Medical Science , University College Dublin , Dublin 4 , Ireland
| | - Amina Ait-Amar
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Faezeh Forouzan Far
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Faiza Fahmi
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Jose Quiel
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Hala El Mekdad
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Fadoua Daouad
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France
| | - Céline Marban
- d Faculté de Chirurgie Dentaire , Inserm UMR 1121 , Strasbourg , France
| | - Olivier Rohr
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France.,b IUT de Schiltigheim , Schiltigheim , France.,e Institut Universitaire de France , Paris , France
| | - Christian Schwartz
- a Institut de Parasitologie et de Pathologie Tropicale, EA7292 , Université de Strasbourg , Strasbourg , France.,b IUT de Schiltigheim , Schiltigheim , France
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12
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Jiang N, Wiemels RE, Soya A, Whitley R, Held M, Faik A. Composition, Assembly, and Trafficking of a Wheat Xylan Synthase Complex. PLANT PHYSIOLOGY 2016; 170:1999-2023. [PMID: 26917684 PMCID: PMC4825154 DOI: 10.1104/pp.15.01777] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Accepted: 02/23/2016] [Indexed: 05/18/2023]
Abstract
Xylans play an important role in plant cell wall integrity and have many industrial applications. Characterization of xylan synthase (XS) complexes responsible for the synthesis of these polymers is currently lacking. We recently purified XS activity from etiolated wheat (Triticum aestivum) seedlings. To further characterize this purified activity, we analyzed its protein composition and assembly. Proteomic analysis identified six main proteins: two glycosyltransferases (GTs) TaGT43-4 and TaGT47-13; two putative mutases (TaGT75-3 and TaGT75-4) and two non-GTs; a germin-like protein (TaGLP); and a vernalization related protein (TaVER2). Coexpression of TaGT43-4, TaGT47-13, TaGT75-3, and TaGT75-4 in Pichia pastoris confirmed that these proteins form a complex. Confocal microscopy showed that all these proteins interact in the endoplasmic reticulum (ER) but the complexes accumulate in Golgi, and TaGT43-4 acts as a scaffold protein that holds the other proteins. Furthermore, ER export of the complexes is dependent of the interaction between TaGT43-4 and TaGT47-13. Immunogold electron microscopy data support the conclusion that complex assembly occurs at specific areas of the ER before export to the Golgi. A di-Arg motif and a long sequence motif within the transmembrane domains were found conserved at the NH2-terminal ends of TaGT43-4 and homologous proteins from diverse taxa. These conserved motifs may control the forward trafficking of the complexes and their accumulation in the Golgi. Our findings indicate that xylan synthesis in grasses may involve a new regulatory mechanism linking complex assembly with forward trafficking and provide new insights that advance our understanding of xylan biosynthesis and regulation in plants.
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Affiliation(s)
- Nan Jiang
- Department of Environmental and Plant Biology (N.J., R.E.W., A.S., R.W., A.F.) and Department of Chemistry and Biochemistry (M.H.), Ohio University, Athens, Ohio 45701
| | - Richard E Wiemels
- Department of Environmental and Plant Biology (N.J., R.E.W., A.S., R.W., A.F.) and Department of Chemistry and Biochemistry (M.H.), Ohio University, Athens, Ohio 45701
| | - Aaron Soya
- Department of Environmental and Plant Biology (N.J., R.E.W., A.S., R.W., A.F.) and Department of Chemistry and Biochemistry (M.H.), Ohio University, Athens, Ohio 45701
| | - Rebekah Whitley
- Department of Environmental and Plant Biology (N.J., R.E.W., A.S., R.W., A.F.) and Department of Chemistry and Biochemistry (M.H.), Ohio University, Athens, Ohio 45701
| | - Michael Held
- Department of Environmental and Plant Biology (N.J., R.E.W., A.S., R.W., A.F.) and Department of Chemistry and Biochemistry (M.H.), Ohio University, Athens, Ohio 45701
| | - Ahmed Faik
- Department of Environmental and Plant Biology (N.J., R.E.W., A.S., R.W., A.F.) and Department of Chemistry and Biochemistry (M.H.), Ohio University, Athens, Ohio 45701
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13
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Malinina L, Simanshu DK, Zhai X, Samygina VR, Kamlekar R, Kenoth R, Ochoa-Lizarralde B, Malakhova ML, Molotkovsky JG, Patel DJ, Brown RE. Sphingolipid transfer proteins defined by the GLTP-fold. Q Rev Biophys 2015; 48:281-322. [PMID: 25797198 PMCID: PMC4691851 DOI: 10.1017/s003358351400016x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Glycolipid transfer proteins (GLTPs) originally were identified as small (~24 kDa), soluble, amphitropic proteins that specifically accelerate the intermembrane transfer of glycolipids. GLTPs and related homologs now are known to adopt a unique, helically dominated, two-layer 'sandwich' architecture defined as the GLTP-fold that provides the structural underpinning for the eukaryotic GLTP superfamily. Recent advances now provide exquisite insights into structural features responsible for lipid headgroup selectivity as well as the adaptability of the hydrophobic compartment for accommodating hydrocarbon chains of differing length and unsaturation. A new understanding of the structural versatility and evolutionary premium placed on the GLTP motif has emerged. Human GLTP-motifs have evolved to function not only as glucosylceramide binding/transferring domains for phosphoinositol 4-phosphate adaptor protein-2 during glycosphingolipid biosynthesis but also as selective binding/transfer proteins for ceramide-1-phosphate. The latter, known as ceramide-1-phosphate transfer protein, recently has been shown to form GLTP-fold while critically regulating Group-IV cytoplasmic phospholipase A2 activity and pro-inflammatory eicosanoid production.
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Affiliation(s)
- Lucy Malinina
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
- Structural Biology Unit, CICbioGUNE, Technology Park of Bizkaia, 48160 Derio-Bilbao, Spain
| | - Dhirendra K. Simanshu
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
| | - Xiuhong Zhai
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Valeria R. Samygina
- Structural Biology Unit, CICbioGUNE, Technology Park of Bizkaia, 48160 Derio-Bilbao, Spain
| | | | - Roopa Kenoth
- The Hormel Institute, University of Minnesota, Austin, MN 55912, USA
| | - Borja Ochoa-Lizarralde
- Structural Biology Unit, CICbioGUNE, Technology Park of Bizkaia, 48160 Derio-Bilbao, Spain
| | | | - Julian G. Molotkovsky
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | - Dinshaw J. Patel
- Structural Biology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
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14
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Sachdeva R, Li Y, Shilpi RY, Simm M. Human X-DING-CD4 mediates resistance to HIV-1 infection through novel paracrine-like signaling. FEBS J 2015; 282:937-50. [PMID: 25581464 DOI: 10.1111/febs.13192] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 01/06/2015] [Accepted: 01/07/2015] [Indexed: 11/30/2022]
Abstract
X-DING-CD4 is a novel phosphatase mediating antiviral responses to HIV-1 infection. This protein is constitutively expressed and secreted by HIV-1 resistant CD4(+) T cells and its mRNA transcription is up-regulated in peripheral blood mononuclear cells from HIV-1 elite controllers. The secreted/soluble X-DING-CD4 protein form is of particular importance because it blocks virus transcription when added to HIV-1 susceptible cells. The present study aimed to determine the contribution of this factor to the induction of the antiviral response in target cells. We found that soluble X-DING-CD4 enters cells by endocytosis and that influx of this protein induced transcription of interferon-α and endogenous X-DING-CD4 mRNA in transformed CD4(+) T cells and primary macrophages. Treatment of HIV-1 susceptible cells with exogenous X-DING-CD4 caused depletion of phosphorylated p50 and p65 nuclear factor kappa β subunits and a significant reduction in p50/p65 nuclear factor kappa β binding to the HIV-1 long terminal repeat. Taken together, these findings indicate a novel antiviral mechanism mediated by the influx of soluble X-DING-CD4, its signaling to promote self-amplification, and functional duality as an endogenous innate immunity effector and exogenous factor regulating gene expression in bystander cells.
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Affiliation(s)
- Rakhee Sachdeva
- Protein Chemistry Laboratory, St Luke's/Roosevelt Institute for Health Sciences, Columbia University, New York, NY, USA
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15
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Biochemical, kinetic, and in silico characterization of DING protein purified from probiotic lactic acid bacteria Pediococcus acidilactici NCDC 252. Appl Biochem Biotechnol 2014; 175:1092-110. [PMID: 25367285 DOI: 10.1007/s12010-014-1306-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 10/15/2014] [Indexed: 01/12/2023]
Abstract
DING proteins are intriguing proteins characterized by conserved N-terminal sequence. In spite of unusually high sequence conservation even between distantly related species, DING proteins exhibit outstanding functional diversity. An extracellular caseinolytic alkaline enzyme was purified to homogeneity from a probiotic lactic acid bacteria Pediococcus acidilactici NCDC 252 using a simple procedure involving ammonium sulphate precipitation and gel filtration chromatography. This was purified 45.72-fold with a yield and specific activity of 43.5 % and 250 U/mg, respectively. The calculated molecular weight was 38.7 and 38.9 kDa by MALDI and SDS-PAGE, respectively, and pI was 7.77. The enzyme exhibited optimal activity at pH 8.0 and 40 °C. It was considerably stable up to pH 12. For casein, the enzyme had K m of 20 μM with V max of 26 U/ml. The enzyme was resistant to organic solvents but sensitive to DTNB and EDTA that confirmed it as thiol protein with involvement of metal ions in catalysis. Its tryptic peptide fragments showed 95 % similarity with eukaryotic DING, i.e., human phosphate binding protein (HPBP). Homology-based structure evaluation using HBPB as template revealed both to be structurally conserved and also possessing conserved phosphate binding motifs.
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16
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Shah M, Zaborin A, Alverdy JC, Scott K, Zaborina O. Localization of DING proteins on PstS-containing outer-surface appendages of Pseudomonas aeruginosa. FEMS Microbiol Lett 2014; 352:54-61. [PMID: 24372739 PMCID: PMC3949141 DOI: 10.1111/1574-6968.12368] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/17/2013] [Accepted: 12/19/2013] [Indexed: 11/30/2022] Open
Abstract
Phosphate signaling and acquisition are critical for the bacterial response to phosphate limitation, and bacteria express multiple factors to scavenge phosphate. We previously found that multidrug-resistant strains of Pseudomonas aeruginosa from critically ill patients can form unusual outer-surface appendages harboring PstS proteins. Here, we have expanded our investigation to DING proteins that like PstS belong to the family of high-affinity phosphate-binding proteins but have strong similarity with eukaryotic DING proteins. We demonstrate the localization of DING on PstS-containing outer-surface appendages in both multidrug-resistant strain MDR25 and the PA14 strain of P. aeruginosa. However, the number of cells producing appendages and the amount of appendages on each cell in PA14 were found to be negligible, unless overexpression of either PstS or DING was achieved by transformation with constructed plasmids. We further noticed that DING expression under low phosphate conditions was significantly higher in MDR25 compared to PA14 which may explain the greater abundance of appendages in MDR25. Our finding that DING proteins are localized on extracellular appendages provides an opportunity to study the interaction of bacterial DING with host proteins by mimicking the action of host DINGs.
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Affiliation(s)
- Megha Shah
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Department of Surgery, Pritzker School of Medicine, University of Chicago, Chicago, IL, USA
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17
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Gai Z, Nakamura A, Tanaka Y, Hirano N, Tanaka I, Yao M. Crystal structure analysis, overexpression and refolding behaviour of a DING protein with single mutation. JOURNAL OF SYNCHROTRON RADIATION 2013; 20:854-858. [PMID: 24121327 PMCID: PMC3795543 DOI: 10.1107/s0909049513020694] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 07/25/2013] [Indexed: 06/02/2023]
Abstract
After crystallization of a certain protein-RNA complex, well diffracting crystals were obtained. However, the asymmetric unit of the crystal was too small to locate any components. Mass spectrometry and X-ray crystal structure analysis showed that it was a member of the DING protein family (HPBP). Surprisingly, the structure of HPBP reported previously was also determined accidentally as a contaminant, suggesting that HPBP has a strong tendency to crystallize. Furthermore, DING proteins were reported to relate in disease. These observations suggest that DING has potential for application in a wide range of research fields. To enable further analyses, a system for preparation of HPBP was constructed. As HPBP was expressed in insoluble form in Escherichia coli, it was unfolded chemically and refolded. Finally, a very high yield preparation method was constructed, in which 43 mg of HPBP was obtained from 1 L of culture. Furthermore, to evaluate the validity of refolding, its crystal structure was determined at 1.03 Å resolution. The determined structure was identical to the native structure, in which two disulfide bonds were recovered correctly and a phosphate ion was captured. Based on these results, it was concluded that the refolded HPBP recovers its structure correctly.
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Affiliation(s)
- Zuoqi Gai
- Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
| | - Akiyoshi Nakamura
- Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
| | - Yoshikazu Tanaka
- Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
- Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Nagisa Hirano
- Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
| | - Isao Tanaka
- Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
- Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Min Yao
- Faculty of Advanced Life Sciences, Hokkaido University, Sapporo 060-0810, Japan
- Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
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18
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Bernier F. DING proteins: numerous functions, elusive genes, a potential for health. Cell Mol Life Sci 2013; 70:3045-56. [PMID: 23743708 PMCID: PMC11113660 DOI: 10.1007/s00018-013-1377-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 04/24/2013] [Accepted: 05/16/2013] [Indexed: 10/26/2022]
Abstract
DING proteins, named after their conserved N-terminus, form an overlooked protein family whose members were generally discovered through serendipity. It is characterized by an unusually high sequence conservation, even between distantly related species, and by an outstanding diversity of activities and ligands. They all share a demonstrated capacity to bind phosphate with high affinity or at least a predicted phosphate-binding site. However, DING protein genes are conspicuously absent from databases. The many novel family members identified in recent years have confirmed that DING proteins are ubiquitous not only in animals and plants but probably also in prokaryotes. At the functional level, there is increasing evidence that they participate in many health-related processes such as cancers as well as bacterial (Pseudomonas) and viral (HIV) infections, by mechanisms that are now beginning to be understood. They thus represent potent targets for the development of novel therapeutic approaches, especially against HIV. The few genomic sequences that are now available are starting to give some clues on why DING protein genes and mRNAs are well conserved and difficult to clone. This could open a new era of research, of both fundamental and applied importance.
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Affiliation(s)
- François Bernier
- Institut de Biologie Moléculaire des Plantes du C.N.R.S., Université de Strasbourg, 28 rue Goethe, 67083, Strasbourg Cedex, France.
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19
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Sachdeva R, Darbinian N, Khalili K, Amini S, Gonzalez D, Djeghader A, Chabriére E, Suh A, Scott K, Simm M. DING proteins from phylogenetically different species share high degrees of sequence and structure homology and block transcription of HIV-1 LTR promoter. PLoS One 2013; 8:e69623. [PMID: 23936341 PMCID: PMC3735540 DOI: 10.1371/journal.pone.0069623] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 06/12/2013] [Indexed: 11/19/2022] Open
Abstract
Independent research groups reported that DING protein homologues isolated from bacterial, plant and human cells demonstrate the anti-HIV-1 activity. This might indicate that diverse organisms utilize a DING-mediated broad-range protective innate immunity response to pathogen invasion, and that this mechanism is effective also against HIV-1. We performed structural analyses and evaluated the anti-HIV-1 activity for four DING protein homologues isolated from different species. Our data show that bacterial PfluDING, plant p38SJ (pDING), human phosphate binding protein (HPBP) and human extracellular DING from CD4 T cells (X-DING-CD4) share high degrees of structure and sequence homology. According to earlier reports on the anti-HIV-1 activity of pDING and X-DING-CD4, other members of this protein family from bacteria and humans were able to block transcription of HIV-1 and replication of virus in cell based assays. The efficacy studies for DING-mediated HIV-1 LTR and HIV-1 replication blocking activity showed that the LTR transcription inhibitory concentration 50 (IC50) values ranged from 0.052–0.449 ng/ml; and the HIV-1 replication IC50 values ranged from 0.075–0.311 ng/ml. Treatment of cells with DING protein alters the interaction between p65-NF-κB and HIV-1 LTR. Our data suggest that DING proteins may be part of an innate immunity defense against pathogen invasion; the conserved structure and activity makes them appealing candidates for development of a novel therapeutics targeting HIV-1 transcription.
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Affiliation(s)
- Rakhee Sachdeva
- Molecular Virology Division, St. Luke's-Roosevelt Institute for Health Sciences/Columbia University, New York, New York, United States of America
| | - Nune Darbinian
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Kamel Khalili
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
| | - Shohreh Amini
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, Pennsylvania, United States of America
- Department of Biology, College of Science and Technology, Temple University, Philadelphia, Pennsylvania, United States of America
| | - Daniel Gonzalez
- Enzymologie Structurale, Université de la Méditerranée, Faculté de Médecine, Marseille, France
| | - Ahmed Djeghader
- Enzymologie Structurale, Université de la Méditerranée, Faculté de Médecine, Marseille, France
| | - Eric Chabriére
- Enzymologie Structurale, Université de la Méditerranée, Faculté de Médecine, Marseille, France
| | - Andrew Suh
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Ken Scott
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Malgorzata Simm
- Molecular Virology Division, St. Luke's-Roosevelt Institute for Health Sciences/Columbia University, New York, New York, United States of America
- * E-mail:
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20
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Suh A, Le Douce V, Rohr O, Schwartz C, Scott K. Pseudomonas DING proteins as human transcriptional regulators and HIV-1 antagonists. Virol J 2013; 10:234. [PMID: 23855931 PMCID: PMC3720264 DOI: 10.1186/1743-422x-10-234] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 05/10/2013] [Indexed: 01/04/2023] Open
Abstract
Background Anti-HIV-1 therapy depends upon multiple agents that target different phases of the viral replication cycle. Recent reports indicate that plant and human DING proteins are unique in targeting viral gene transcription as the basis of their anti-HIV-1 therapy. Methods Two cloned DING genes from Pseudomonas were transiently expressed in human cells, and effects on NFκB-mediated transcription, HIV-1 transcription, and HIV-1 production were measured. Results Both DING proteins elevated NFκB-mediated transcription. In microglial cells, one protein, from P. aeruginosa PA14, suppressed HIV-1 transcription; the other protein, from P. fluorescens SBW25, was inactive. The PA14DING protein also reduces HIV-1 production in microglial cells. Conclusions Structural differences between the two DING proteins highlight regions of the PA14DING protein essential to the anti-HIV-1 activity, and may guide the design of therapeutic agents.
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Affiliation(s)
- Andrew Suh
- School of Biological Sciences, University of Auckland, Private Bag, Auckland 92019, New Zealand
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21
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Djeghader A, Gotthard G, Suh A, Gonzalez D, Scott K, Elias M, Chabriere E. Crystallization and preliminary X-ray diffraction analysis of a DING protein from Pseudomonas aeruginosa PA14. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:425-9. [PMID: 23545651 PMCID: PMC3614170 DOI: 10.1107/s1744309113005356] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 02/24/2013] [Indexed: 11/10/2022]
Abstract
DING proteins form an emergent family of proteins consisting of an increasing number of homologues that have been identified in all kingdoms of life. They belong to the superfamily of phosphate-binding proteins and exhibit a high affinity for phosphate. In eukaryotes, DING proteins have been isolated by virtue of their implication in several diseases and biological processes. Some of them are potent inhibitors of HIV-1 replication/transcription, raising the question of their potential involvement in the human defence system. Recently, a protein from Pseudomonas aeruginosa strain PA14, named PA14DING or LapC, belonging to the DING family has been identified. The structure of PA14DING, combined with detailed biochemical characterization and comparative analysis with available DING protein structures, will be helpful in understanding the structural determinants implicated in the inhibition of HIV-1 by DING proteins. Here, the expression, purification and crystallization of PA14DING and the collection of X-ray data to 1.9 Å resolution are reported.
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Affiliation(s)
- Ahmed Djeghader
- Aix-Marseille Université, URMITE, UM63, CNRS 7278, IRD 198, Inserm 1095, 27 Boulevard Jean Moulin, 13385 Marseille CEDEX 5, France
| | - Guillaume Gotthard
- Aix-Marseille Université, URMITE, UM63, CNRS 7278, IRD 198, Inserm 1095, 27 Boulevard Jean Moulin, 13385 Marseille CEDEX 5, France
| | - Andrew Suh
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Daniel Gonzalez
- Aix-Marseille Université, URMITE, UM63, CNRS 7278, IRD 198, Inserm 1095, 27 Boulevard Jean Moulin, 13385 Marseille CEDEX 5, France
| | - Ken Scott
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Mikael Elias
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Eric Chabriere
- Aix-Marseille Université, URMITE, UM63, CNRS 7278, IRD 198, Inserm 1095, 27 Boulevard Jean Moulin, 13385 Marseille CEDEX 5, France
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22
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Type II-dependent secretion of a Pseudomonas aeruginosa DING protein. Res Microbiol 2012; 163:457-69. [PMID: 22835944 DOI: 10.1016/j.resmic.2012.07.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 07/16/2012] [Indexed: 11/24/2022]
Abstract
Pseudomonas aeruginosa is an opportunistic bacterial pathogen that uses a wide range of protein secretion systems to interact with its host. Genes encoding the PAO1 Hxc type II secretion system are linked to genes encoding phosphatases (LapA/LapB). Microarray genotyping suggested that Pseudomonas aeruginosa clinical isolates, including urinary tract (JJ692) and blood (X13273) isolates, lacked the lapA/lapB genes. Instead, we show that they carry a gene encoding a protein of the PstS family. This protein, which we call LapC, also has significant similarities with LapA/LapB. LapC belongs to the family of DING proteins and displays the canonical DINGGG motif within its N terminus. DING proteins are members of a prokaryotic phosphate binding protein superfamily. We show that LapC is secreted in an Hxc-dependent manner and is under the control of the PhoB response regulator. The genetic organization hxc-lapC found in JJ692 and X13273 is similar to PA14, which is the most frequent P. aeruginosa genotype. While the role of LapA, LapB and LapC proteins remains unclear in P. aeruginosa pathogenesis, they are likely to be part of a phosphate scavenging or sensing system needed to survive and thrive when low phosphate environments are encountered within the host.
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23
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Bookland MJ, Darbinian N, Weaver M, Amini S, Khalili K. Growth inhibition of malignant glioblastoma by DING protein. J Neurooncol 2011; 107:247-56. [PMID: 22052333 DOI: 10.1007/s11060-011-0743-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Accepted: 10/20/2011] [Indexed: 11/25/2022]
Abstract
Malignant gliomas are a highly aggressive type of brain tumor with extremely poor prognosis. These tumors are highly invasive and are often surgically incurable and resistant to chemotherapeutics and radiotherapy. Thus, novel therapies that target pathways involved in growth and survival of the tumor cells are required for the treatment of this class of brain tumors. Previous studies revealed that epidermal growth factor receptor and extracellular-signal-regulated kinases (ERKs), which are involved in the induction of cell proliferation, are activated in the most aggressive type of glioma, i.e. glioblastoma multiforme (GBM). In fact, GBMs with increased levels of ERK activity exhibit a more aggressive phenotype than the others with moderate ERK activity, pointing to the importance of ERK and its kinase activity in the development and progression of these tumors. In this study, we have evaluated the effect of p38SJ, a novel member of the DING family of proteins, derived from Hypericum perforatum calluses, on the growth of malignant glioma cell lines, T98G and U-87MG by focusing on cell cycle and signaling pathways controlled by phosphorylation of various regulatory proteins including ERK. p38SJ, which exhibits profound phosphatase activity, shows the capacity to affect the phosphorylation status of several important kinases modulating signaling pathways, and cell growth and proliferation. Our results demonstrate that p38SJ reduces glioma cell viability and arrests cell cycle progression at G0/G1. The observed growth inhibitory effect of p38SJ is likely mediated by the downregulation of several cell cycle gatekeeper proteins, including cyclin E, Cdc2, and E2F-1. These results suggest that p38SJ may serve as a potential candidate for development of a therapeutic agent for the direct treatment of malignant gliomas and/or as a potential radiosensitizer.
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Affiliation(s)
- Markus J Bookland
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, Room 741 MERB, 3500 North Broad St., Philadelphia, PA 19140, USA
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24
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Darbinian N, Gomberg R, Mullen L, Garcia S, White MK, Khalili K, Amini S. Suppression of HIV-1 transcriptional elongation by a DING phosphatase. J Cell Biochem 2011; 112:225-32. [PMID: 21117063 DOI: 10.1002/jcb.22915] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
HIV-1 gene transcription is controlled by the cooperation of viral and host factors which bind to specific DNA sequences within the viral promoter spanning the long terminal repeat (LTR). Previously we showed that the St. John's Wort DING phosphatase, p27SJ, suppresses HIV-1 gene transcription by binding to the viral protein Tat and preventing its nuclear import. Here, we describe the inhibitory effect of p27SJ on the phosphorylation of the C-terminal domain (CTD) of RNA polymerase II (RNAPII). This inhibition leads to the suppression of the association of RNAPII with the LTR. Inhibition of binding of RNAPII to LTR by p27SJ resulted in the suppression of LTR transcription elongation and a decrease in LTR transcriptional activity. Another form of the St. John's Wort DING phosphatase, p38SJ, also suppressed binding of RNAPII to the LTR, reduced transcription elongation and was even more powerful than p27SJ in inhibiting the transcriptional activity of the LTR. Our data suggest a possible mechanism by which the p27SJ/p38SJ DING phosphatase can regulate HIV-1 LTR expression by inhibiting phosphorylation of the CTD of RNAPII and suppressing LTR transcription elongation.
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Affiliation(s)
- Nune Darbinian
- Department of Neuroscience, Temple University School of Medicine, Philadelphia, PA 19140, USA
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25
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Cherrier T, Elias M, Jeudy A, Gotthard G, Le Douce V, Hallay H, Masson P, Janossy A, Candolfi E, Rohr O, Chabrière E, Schwartz C. Human-Phosphate-Binding-Protein inhibits HIV-1 gene transcription and replication. Virol J 2011; 8:352. [PMID: 21762475 PMCID: PMC3157455 DOI: 10.1186/1743-422x-8-352] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 07/15/2011] [Indexed: 01/04/2023] Open
Abstract
The Human Phosphate-Binding protein (HPBP) is a serendipitously discovered lipoprotein that binds phosphate with high affinity. HPBP belongs to the DING protein family, involved in various biological processes like cell cycle regulation. We report that HPBP inhibits HIV-1 gene transcription and replication in T cell line, primary peripherical blood lymphocytes and primary macrophages. We show that HPBP is efficient in naïve and HIV-1 AZT-resistant strains. Our results revealed HPBP as a new and potent anti HIV molecule that inhibits transcription of the virus, which has not yet been targeted by HAART and therefore opens new strategies in the treatment of HIV infection.
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Affiliation(s)
- Thomas Cherrier
- Institut de Parasitologie et Pathologie Tropicale, EA 4438, Université de Strasbourg, 3 rue Koeberlé, 67000 Strasbourg, France
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26
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Cherrier T, Le Douce V, Redel L, Marban C, Aunis D, Rohr O, Schwartz C. [Molecular basis of HIV-1 latency - Part II: HIV-1 reactivation and therapeutic implications]. Med Sci (Paris) 2010; 26:291-5. [PMID: 20346279 DOI: 10.1051/medsci/2010263291] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The latent HIV-1 reservoirs established early during infection present a major obstacle for virus eradication. Complete eradication of the virus from infected patients may require a purge of the reservoirs. Since the development of a HIV-1 vaccine is not achieved, and therefore remains a major challenge for the immunologists, future direction towards an effective curative therapy for HIV-1 infection will rely on the development of original therapeutic strategies which take into account latency, chronic replication and accessibility to tissue-sanctuary.
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Affiliation(s)
- Thomas Cherrier
- Inserm Unité 575 Physiopathologie du système nerveux central, Institut de virologie, 3, rue Koeberlé, 67000 Strasbourg, France
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27
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Collombet JM, Elias M, Gotthard G, Four E, Renault F, Joffre A, Baubichon D, Rochu D, Chabrière E. Eukaryotic DING proteins are endogenous: an immunohistological study in mouse tissues. PLoS One 2010; 5:e9099. [PMID: 20161715 PMCID: PMC2817009 DOI: 10.1371/journal.pone.0009099] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 01/20/2010] [Indexed: 11/19/2022] Open
Abstract
Background DING proteins encompass an intriguing protein family first characterized by their conserved N-terminal sequences. Some of these proteins seem to have key roles in various human diseases, e.g., rheumatoid arthritis, atherosclerosis, HIV suppression. Although this protein family seems to be ubiquitous in eukaryotes, their genes are consistently lacking from genomic databases. Such a lack has considerably hampered functional studies and has fostered therefore the hypothesis that DING proteins isolated from eukaryotes were in fact prokaryotic contaminants. Principal Findings In the framework of our study, we have performed a comprehensive immunological detection of DING proteins in mice. We demonstrate that DING proteins are present in all tissues tested as isoforms of various molecular weights (MWs). Their intracellular localization is tissue-dependant, being exclusively nuclear in neurons, but cytoplasmic and nuclear in other tissues. We also provide evidence that germ-free mouse plasma contains as much DING protein as wild-type. Significance Hence, data herein provide a valuable basis for future investigations aimed at eukaryotic DING proteins, revealing that these proteins seem ubiquitous in mouse tissue. Our results strongly suggest that mouse DING proteins are endogenous. Moreover, the determination in this study of the precise cellular localization of DING proteins constitute a precious evidence to understand their molecular involvements in their related human diseases.
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Affiliation(s)
- Jean-Marc Collombet
- Département de Toxicologie, Institut de Recherche Biomédicale des Armées, Centre de Recherche du Service de Santé des Armées, La Tronche, France
| | - Mikael Elias
- Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique-Aix Marseille Université, Marseille, France
| | - Guillaume Gotthard
- Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique-Aix Marseille Université, Marseille, France
| | - Elise Four
- Département de Toxicologie, Institut de Recherche Biomédicale des Armées, Centre de Recherche du Service de Santé des Armées, La Tronche, France
| | - Frédérique Renault
- Département de Toxicologie, Institut de Recherche Biomédicale des Armées, Centre de Recherche du Service de Santé des Armées, La Tronche, France
| | - Aurélie Joffre
- Service de Microscopie et d'Imagerie Médicale, Institut de Recherche Biomédicale des Armées, Centre de Recherche du Service de Santé des Armées, La Tronche, France
| | - Dominique Baubichon
- Département de Toxicologie, Institut de Recherche Biomédicale des Armées, Centre de Recherche du Service de Santé des Armées, La Tronche, France
| | - Daniel Rochu
- Département de Toxicologie, Institut de Recherche Biomédicale des Armées, Centre de Recherche du Service de Santé des Armées, La Tronche, France
| | - Eric Chabrière
- Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique-Aix Marseille Université, Marseille, France
- * E-mail:
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28
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Amini S, Merabova N, Khalili K, Darbinian N. p38SJ, a novel DINGG protein protects neuronal cells from alcohol induced injury and death. J Cell Physiol 2009; 221:499-504. [PMID: 19739100 DOI: 10.1002/jcp.21903] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Ethanol induces neuronal cell injury and death by dysregulating several signaling events that are controlled, in part, by activation of MAPK/ERK1/2 and/or inactivation of its corresponding phosphatase, PP1. Recently, we have purified a novel protein of 38 kDa in size, p38SJ, from a callus culture of Hypericum perforatum, which belongs to an emerging DINGG family of proteins with phosphate binding activity. Here, we show that treatment of neuronal cells with p38SJ protects cells against injury induced by exposure to ethanol. Furthermore, pre-treatment of neuronal cells with p38SJ diminishes the level of the pro-apoptotic protein Bax and some events associated with apoptosis such as caspase 3 cleavage. In addition, by inducing stress, alcohol can elevate production of reactive oxygen species (ROS) that leads to a decrease in the activity of superoxide dismutase (SOD). Our results showed that p38SJ restores the activity of SOD in the ethanol treated neuronal cells. These observations provide a novel biological tool for developing new approaches for preventing neuronal cell death induced by ethanol and possibly treatment of neurological disorders associated with alcohol abuse.
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Affiliation(s)
- Shohreh Amini
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania 19122, USA.
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29
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Redel L, Le Douce V, Cherrier T, Marban C, Janossy A, Aunis D, Van Lint C, Rohr O, Schwartz C. HIV-1 regulation of latency in the monocyte-macrophage lineage and in CD4+ T lymphocytes. J Leukoc Biol 2009; 87:575-88. [PMID: 19801499 DOI: 10.1189/jlb.0409264] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The introduction in 1996 of the HAART raised hopes for the eradication of HIV-1. Unfortunately, the discovery of latent HIV-1 reservoirs in CD4+ T cells and in the monocyte-macrophage lineage proved the optimism to be premature. The long-lived HIV-1 reservoirs constitute a major obstacle to the eradication of HIV-1. In this review, we focus on the establishment and maintenance of HIV-1 latency in the two major targets for HIV-1: the CD4+ T cells and the monocyte-macrophage lineage. Understanding the cell-type molecular mechanisms of establishment, maintenance, and reactivation of HIV-1 latency in these reservoirs is crucial for efficient therapeutic intervention. A complete viral eradication, the holy graal for clinicians, might be achieved by strategic interventions targeting latently and productively infected cells. We suggest that new approaches, such as the combination of different kinds of proviral activators, may help to reduce dramatically the size of latent HIV-1 reservoirs in patients on HAART.
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Affiliation(s)
- Laetitia Redel
- INSERM Unit 575, Pathophysiology of Central Nervous System, Institute of Virology, Strasbourg, France
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30
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Darbinian N, Czernik M, Darbinyan A, Elias M, Chabriere E, Bonasu S, Khalili K, Amini S. Evidence for phosphatase activity of p27SJ and its impact on the cell cycle. J Cell Biochem 2009; 107:400-7. [PMID: 19343785 DOI: 10.1002/jcb.22135] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
p27SJ, a novel protein isolated from St John's wort (Hypericum perforatum), belongs to an emerging family of DING proteins that are related to a prokaryotic phosphate-binding protein superfamily. Here we demonstrate that p27SJ exhibits phosphatase activity and that its expression in cells decreases the level of phosphorylated Erk1/2, a key protein of several signaling pathways. Treatment of p27SJ-expressing cells with phosphatase inhibitors including okadaic acid, maintained Erk1/2 in its phosphorylated form, suggesting that dephosphorylation of Erk1/2 is mediated by p27SJ. Further, expression of p27SJ affects Erk1/2 downstream regulatory targets such as STAT3 and CREB. Moreover, the level of expression of cyclin A that associates with active ERK1/2 and is regulated by CREB, was modestly reduced in p27SJ-expressing cells. Accordingly, results from in vitro kinase assays revealed a noticeable decrease in the activity of cyclin A in cells expressing p27SJ. Cell cycle analysis demonstrated dysregulation at S and G2/M phases in cells expressing p27SJ, supporting the notion that a decline in cyclin A activity by p27SJ has a biological impact on cell growth. These observations provide evidence that p27SJ alters the state of Erk1/2 phosphorylation, and impacts several biological events associated with cell growth and function.
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Affiliation(s)
- Nune Darbinian
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania 19122, USA
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31
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Lesner A, Shilpi R, Ivanova A, Gawinowicz MA, Lesniak J, Nikolov D, Simm M. Identification of X-DING-CD4, a new member of human DING protein family that is secreted by HIV-1 resistant CD4(+) T cells and has anti-viral activity. Biochem Biophys Res Commun 2009; 389:284-9. [PMID: 19720052 DOI: 10.1016/j.bbrc.2009.08.140] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Accepted: 08/25/2009] [Indexed: 10/20/2022]
Abstract
We reported previously the anti-viral activity named HRF (HIV-1 Resistance Factor) secreted by HIV-1 resistant cells. This work describes the identification of HRF from cell culture supernatant of HRF-producing cells (HRF(+) cells). Employing the proteomics and cell based activity assay we recovered ten peptides sharing 80-93% sequence homology with other eukaryotic DING proteins; discrete amino acid characteristics found in our material suggested that HRF is a new member of DING proteins family and consequently we designated it as X-DING-CD4 (extracellular DING from CD4(+) T cells). The presence of X-DING-CD4 in the extracellular compartment of HRF(+) but not control HRF(-) cells was confirmed by specific anti-X-DING-CD4 antibody. Similar as the un-fractionated HRF(+) cell culture supernatant, the purified X-DING-CD4 blocked transcription of HIV-1 LTR-promoted expression of luciferase gene and replication of HIV-1 in MAGI cells. The X-DING-CD4 -mediated anti-viral activity in MAGI cells could be blocked by specific antibody.
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Affiliation(s)
- Adam Lesner
- Protein Chemistry Laboratory, St. Luke's/Roosevelt Institute for Health Sciences, Columbia University, New York, NY 10019, USA
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32
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Liebschner D, Elias M, Moniot S, Fournier B, Scott K, Jelsch C, Guillot B, Lecomte C, Chabrière E. Elucidation of the phosphate binding mode of DING proteins revealed by subangstrom X-ray crystallography. J Am Chem Soc 2009; 131:7879-86. [PMID: 19445459 DOI: 10.1021/ja901900y] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PfluDING is a bacterial protein isolated from Pseudomonas fluorescens that belongs to the DING protein family, which is ubiquitous in eukaryotes and extends to prokaryotes. DING proteins and PfluDING have very similar topologies to phosphate Solute Binding Proteins (SBPs). The three-dimensional structure of PfluDING was obtained at subangstrom resolution (0.88 and 0.98 A) at two different pH's (4.5 and 8.5), allowing us to discuss the hydrogen bond network that sequesters the phosphate ion in the binding site. From this high resolution data, we experimentally elucidated the molecular basis of phosphate binding in phosphate SBPs. The phosphate ion is tightly bound to the protein via 12 hydrogen bonds between phosphate oxygen atoms and OH and NH groups of the protein. The proton on one oxygen atom of the phosphate dianion forms a 2.5 A low barrier hydrogen bond with an aspartate, with the energy released by forming this strong bond ensuring the specificity for the dianion even at pH 4.5. In particular, contrary to previous theories on phosphate SBPs, accurate electrostatic potential calculations show that the binding cleft is positively charged. PfluDING structures reveal that only dibasic phosphate binds to the protein at both acidic and basic phosphate, suggesting that the protein binding site environment stabilizes the HPO(4)(2-) form of phosphate.
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Affiliation(s)
- Dorothee Liebschner
- Cristallographie Resonnance Magnetique et Modelisations, CNRS UMR 7036 Nancy-Universite, 54506 Vandoeuvre-les-Nancy, France
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33
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Berna A, Bernier F, Chabrière E, Elias M, Scott K, Suh A. For whom the bell tolls? DING proteins in health and disease. Cell Mol Life Sci 2009; 66:2205-18. [PMID: 19290474 PMCID: PMC11115607 DOI: 10.1007/s00018-009-0006-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2008] [Revised: 02/09/2009] [Accepted: 02/13/2009] [Indexed: 11/29/2022]
Abstract
DING proteins, identified mainly by their eponymous N-terminal sequences, are ubiquitous in living organisms. Amongst bacteria, they are common in pseudomonads, and have been characterised with respect to genetics and structure. They form part of a wider family of phosphate-binding proteins, with emerging roles in phosphate acquisition and pathogenicity. Many DING proteins have been isolated in eukaryotes, in which they have been associated with very diverse biological activities, often in the context of possible signalling roles. Disease states in which DING proteins have been implicated include rheumatoid arthritis, lithiasis, atherosclerosis, some tumours and tumour-associated cachexia, and bacterial and viral adherence. Complete genetic and structural characterisation of eukaryotic DING genes and proteins is still lacking, though the phosphate-binding site seems to be conserved. Whether as bacterial proteins related to bacterial pathogenicity, or as eukaryotic components of biochemical signalling systems, DING proteins require further study.
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Affiliation(s)
- Anne Berna
- Institut de Biologie Moléculaire des Plantes du CNRS, Institut de Botanique, Université de Strasbourg, 28 rue Goethe, Strasbourg Cedex, France.
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34
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Berna A, Scott K, Chabrière E, Bernier F. The DING family of proteins: ubiquitous in eukaryotes, but where are the genes? Bioessays 2009; 31:570-80. [PMID: 19360767 DOI: 10.1002/bies.200800174] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PstS and DING proteins are members of a superfamily of secreted, high-affinity phosphate-binding proteins. Whereas microbial PstS have a well-defined role in phosphate ABC transporters, the physiological function of DING proteins, named after their DINGGG N termini, still needs to be determined. PstS and DING proteins co-exist in some Pseudomonas strains, to which they confer a highly adhesive and virulent phenotype. More than 30 DING proteins have now been purified, mostly from eukaryotes. They are often associated with infections or with dysregulation of cell proliferation. Consequently, eukaryotic DING proteins could also be involved in cell-cell communication or adherence. The ubiquitous presence in eukaryotes of proteins structurally and functionally related to bacterial virulence factors is intriguing, as is the absence of eukaryotic genes encoding DING proteins in databases. DING proteins in eukaryotes could originate from unidentified commensal or symbiotic bacteria and could contribute to essential functions. Alternatively, DING proteins could be encoded by eukaryotic genes sharing special features that prevent their cloning. Both hypotheses are discussed.
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Affiliation(s)
- Anne Berna
- Institut de Biologie Moléculaire des Plantes du CNRS, Université Louis Pasteur, Institut de Botanique, Strasbourg Cedex, France
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35
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Di Maro A, De Maio A, Castellano S, Parente A, Farina B, Faraone-Mennella MR. The ADP-ribosylating thermozyme from Sulfolobus solfataricus is a DING protein. Biol Chem 2009; 390:27-30. [PMID: 19007307 DOI: 10.1515/bc.2009.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The partial amino acid sequence of the sulfolobal thermoprotein biochemically characterized as poly(ADP-ribose)polymerase-like enzyme overlaps those of DING proteins. This group of proteins, widely occurring in animals, plants and eubacteria, shows a characteristic and highly conserved N-terminus, DINGGGATL. The sequence of the N-terminal region and of the analyzed tryptic peptides of the sulfolobal thermozyme shows a high similarity with most of the DING proteins from databases. This is the first example of a DING protein from a sulfolobal source.
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Affiliation(s)
- Antimo Di Maro
- Department of Life Sciences, Faculty of Sciences M.F.N., Second University of Naples, Via Vivadi 45, I-81100 Caserta, Italy
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36
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Zaborina O, Holbrook C, Chen Y, Long J, Zaborin A, Morozova I, Fernandez H, Wang Y, Turner JR, Alverdy JC. Structure-function aspects of PstS in multi-drug-resistant Pseudomonas aeruginosa. PLoS Pathog 2008; 4:e43. [PMID: 18282104 PMCID: PMC2242829 DOI: 10.1371/journal.ppat.0040043] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Accepted: 01/07/2008] [Indexed: 01/10/2023] Open
Abstract
The increasing prevalence of multi-drug-resistant (MDR) strains of Pseudomonas aeruginosa among critically ill humans is of significant concern. In the current study, we show that MDR clinical isolates of P. aeruginosa representing three distinct genotypes that display high virulence against intestinal epithelial cells, form novel appendage-like structures on their cell surfaces. These appendages contain PstS, an extracellular phosphate binding protein. Using anti-PstS antibodies, we determined that the PstS-rich appendages in MDR strains are involved in adherence to and disruption of the integrity of cultured intestinal epithelial cell monolayers. The outer surface-expressed PstS protein was also identified to be present in P. aeruginosa MPAO1, although to a lesser degree, and its role in conferring an adhesive and barrier disruptive phenotype against intestinal epithelial cells was confirmed using an isogenic DeltaPstS mutant. Formation of the PstS rich appendages was induced during phosphate limitation and completely suppressed in phosphate-rich media. Injection of MDR strains directly into the intestinal tract of surgically injured mice, a known model of phosphate limitation, caused high mortality rates (60%-100%). Repletion of intestinal phosphate in this model completely prevented mortality. Finally, significantly less outer surface PstS was observed in the MPAO1 mutant DeltaHxcR thus establishing a role for the alternative type II secretion system Hxc in outer surface PstS expression. Gene expression analysis performed by RT-PCR confirmed this finding and further demonstrated abundant expression of pstS analogous to pa5369, pstS analogous to pa0688/pa14-55410, and hxcX in MDR strains. Taken together, these studies provide evidence that outer surface PstS expression confers a highly virulent phenotype of MDR isolates against the intestinal epithelium that alters their adhesive and barrier disrupting properties against the intestinal epithelium.
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Affiliation(s)
- Olga Zaborina
- Department of Surgery, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, United States of America
| | - Christopher Holbrook
- Department of Surgery, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, United States of America
| | - Yimei Chen
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, United States of America
| | - Jason Long
- Department of Surgery, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, United States of America
| | - Alexander Zaborin
- Department of Surgery, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, United States of America
| | - Irina Morozova
- Department of Surgery, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, United States of America
| | - Hoylan Fernandez
- Department of Surgery, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, United States of America
| | - Yingmin Wang
- Department of Pathology, University of Chicago, Chicago, Illinois, United States of America
| | - Jerrold R Turner
- Department of Pathology, University of Chicago, Chicago, Illinois, United States of America
| | - John C Alverdy
- Department of Surgery, Pritzker School of Medicine, University of Chicago, Chicago, Illinois, United States of America
- * To whom correspondence should be addressed. E-mail:
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Perera T, Berna A, Scott K, Lemaitre-Guillier C, Bernier F. Proteins related to St. John's Wort p27SJ, a suppressor of HIV-1 expression, are ubiquitous in plants. PHYTOCHEMISTRY 2008; 69:865-72. [PMID: 18006028 DOI: 10.1016/j.phytochem.2007.10.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Revised: 09/28/2007] [Accepted: 10/01/2007] [Indexed: 05/25/2023]
Abstract
Proteins belonging to the family of DING proteins are ubiquitous in animals and several of them are associated with various diseases. Their presence in a few plant species has previously been reported and the St John's Wort DING protein was recently described as an inhibitor of HIV replication and transcription. However, data about DING protein occurrence in plants and their biochemical properties remain almost nonexistent. We describe methods for the purification of DING proteins from plants that may have general applicability since they are not dependent upon specific affinity ligands, contrary to previously described protocols. Cibacron Blue chromatography, sometimes preceded by an ion-exchange chromatographic step, is suitable for most plant extracts. DING proteins were purified from various species and cell types and their identity was confirmed immunologically and, in some cases, by N-terminal sequence analysis, indicating that they are ubiquitous in the plant kingdom. They are associated with the cell wall and sometimes secreted in the medium for in vitro grown cells. High-molecular-weight DING precursors were often observed. Internal peptides were also sequenced, as a prelude to gene cloning experiments.
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Affiliation(s)
- Tekla Perera
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
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Creation of a bi-directional protein transduction system for suppression of HIV-1 expression by p27SJ. Antiviral Res 2007; 79:136-41. [PMID: 18378326 DOI: 10.1016/j.antiviral.2007.11.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Revised: 11/16/2007] [Accepted: 11/19/2007] [Indexed: 11/24/2022]
Abstract
p27SJ is a novel protein from a callus culture of St. John's wort that modulates transcription of the HIV-1 promoter in several mammalian cells [Darbinian-Sarkissian, N., Darbinyan, A., Otte, J., Radhakrishnan, S., Sawaya, B.E., Arzumanyan, A., Chipitsyna, G., Popov, Y., Rappaport, J., Amini, S., Khalili, K., 2006. p27(SJ), a novel protein from St. John's wort, that suppresses expression of HIV-1 genome. Gene Ther. 13, 288-295]. Here, we armed p27SJ with signals from Ig-kappa light chain that allow its efficient excretion from the cells, and from HIV-1 Tat that facilitates its uptake by other cells for its utilization by a protein transduction method. We demonstrate that treatment of cells containing the HIV-1 LTR with conditioned media from cells expressing the armed p27SJ ((exc)p27SJ(upt)) results in suppression of the viral activation by the C/EBPbeta transcription factor. Once imported into the cells, (exc)p27SJ(upt) impacts the nuclear localization of C/EBPbeta and by retaining the protein in the cytoplasm affects its DNA binding and hence transcriptional activity. The armed p27SJ also inhibits Tat-induced activation of the LTR and decreases the level of viral replication in promonocytic cells including U-937 and T-lymphocytic cells. Our observations introduce a new bi-directional protein transduction system with a broad spectrum of applications for manufacturing therapeutic peptides by a specific group of cells called donor, and delivery to the target cells named recipient. Furthermore, our results support the utility of soluble p27SJ in suppressing transcription and replication of HIV-1 by interfering with the function of cellular proteins such as C/EBPbeta and viral activators including Tat.
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Zhang XX, Scott K, Meffin R, Rainey PB. Genetic characterization of psp encoding the DING protein in Pseudomonas fluorescens SBW25. BMC Microbiol 2007; 7:114. [PMID: 18088430 PMCID: PMC2225411 DOI: 10.1186/1471-2180-7-114] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Accepted: 12/18/2007] [Indexed: 11/13/2022] Open
Abstract
Background DING proteins constitute a conserved and broadly distributed set of proteins found in bacteria, fungi, plants and animals (including humans). Characterization of DING proteins from animal and plant tissues indicated ligand-binding ability suggesting a role for DING proteins in cell signaling and biomineralization. Surprisingly, the genes encoding DING proteins in eukaryotes have not been identified in the eukaryotic genome or EST databases. Recent discovery of a DING homologue (named Psp here) in the genome of Pseudomonas fluorescens SBW25 provided a unique opportunity to investigate the physiological roles of DING proteins. P. fluorescens SBW25 is a model bacterium that can efficiently colonize plant surfaces and enhance plant health. In this report we genetically characterize Psp with a focus on conditions under which psp is expressed and the protein exported. Results Psp is closely related to the periplasmic Pi binding component of the ABC-type phosphate transporter system (Pst). psp is flanked by a gene cluster predicted to function as a type II protein secretion system (Hxc). Deletion analysis combined with chromosomally integrated 'lacZ fusions showed that both psp and pstC are induced by Pi limitation and that pstC is required for competitive growth of the bacterium in Pi limited medium. hxcR is not regulated by Pi limitation. Psp was detected (using anti-DING serum) in the supernatant of wild-type culture but was greatly reduced in the supernatant of an isogenic strain carrying an hxcR mutation (ΔhxcR). A promoter fusion between hxcR and a promoterless copy of a gene ('dapB) essential for growth in the plant environment showed that expression of hxcR is elevated during colonization of sugar beet seedlings. A similar analysis of psp showed that it is not induced in the plant environment. Conclusion Psp gene is expressed under conditions of Pi limitation. It is an exoprotein secreted mainly via the Hxc type II secretion system, whose expression is elevated on plant surfaces. We propose that Psp is involved in extracellular scavenging of phosphates, which are subsequently taken up by the cell-bound Pst transport system.
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Affiliation(s)
- Xue-Xian Zhang
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand.
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Ahn S, Moniot S, Elias M, Chabriere E, Kim D, Scott K. Structure-function relationships in a bacterial DING protein. FEBS Lett 2007; 581:3455-60. [PMID: 17612529 DOI: 10.1016/j.febslet.2007.06.050] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 06/20/2007] [Accepted: 06/20/2007] [Indexed: 10/23/2022]
Abstract
A recombinant DING protein from Pseudomonas fluorescens has been previously shown to have a phosphate-binding site, and to be mitogenic for human cells. Here we report the three-dimensional structure of the protein, confirming a close similarity to the "Venus flytrap" structure seen in other human and bacterial phosphate-binding proteins. Site-directed mutagenesis confirms the role of a key residue involved in phosphate binding, and that the mitogenic activity is not dependent on this property. Deletion of one of the two hinged domains that constitute the Venus flytrap also eliminates phosphate binding whilst enhancing mitogenic activity.
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Affiliation(s)
- Soyeon Ahn
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
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