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Nygaard L, Vogelius I, Håkansson K, Langer S, Persson G, Bentzen S. EP-1229: Non-small cell lung cancer: marked difference in first failure site depending on histology. Radiother Oncol 2016. [DOI: 10.1016/s0167-8140(16)32479-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Holmkvist P, Roepstorff K, Uronen-Hansson H, Sandén C, Gudjonsson S, Patschan O, Grip O, Marsal J, Schmidtchen A, Hornum L, Erjefält JS, Håkansson K, Agace WW. A major population of mucosal memory CD4+ T cells, coexpressing IL-18Rα and DR3, display innate lymphocyte functionality. Mucosal Immunol 2015; 8:545-58. [PMID: 25269704 PMCID: PMC4424383 DOI: 10.1038/mi.2014.87] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 08/18/2014] [Indexed: 02/04/2023]
Abstract
Mucosal tissues contain large numbers of memory CD4(+) T cells that, through T-cell receptor-dependent interactions with antigen-presenting cells, are believed to have a key role in barrier defense and maintenance of tissue integrity. Here we identify a major subset of memory CD4(+) T cells at barrier surfaces that coexpress interleukin-18 receptor alpha (IL-18Rα) and death receptor-3 (DR3), and display innate lymphocyte functionality. The cytokines IL-15 or the DR3 ligand tumor necrosis factor (TNF)-like cytokine 1A (TL1a) induced memory IL-18Rα(+)DR3(+)CD4(+) T cells to produce interferon-γ, TNF-α, IL-6, IL-5, IL-13, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-22 in the presence of IL-12/IL-18. TL1a synergized with IL-15 to enhance this response, while suppressing IL-15-induced IL-10 production. TL1a- and IL-15-mediated cytokine induction required the presence of IL-18, whereas induction of IL-5, IL-13, GM-CSF, and IL-22 was IL-12 independent. IL-18Rα(+)DR3(+)CD4(+) T cells with similar functionality were present in human skin, nasal polyps, and, in particular, the intestine, where in chronic inflammation they localized with IL-18-producing cells in lymphoid aggregates. Collectively, these results suggest that human memory IL-18Rα(+)DR3(+) CD4(+) T cells may contribute to antigen-independent innate responses at barrier surfaces.
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Rasmussen J, Vogelius I, Fischer B, Aznar M, Friborg J, Håkansson K, Persson G, Kristensen C, Bentzen S, Specht L. Prognostic Value of FDG Uptake in 287 Patients With Head-and-Neck Squamous Cell Carcinoma. Int J Radiat Oncol Biol Phys 2014. [DOI: 10.1016/j.ijrobp.2013.11.113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Zhou W, Håkansson K. Electron capture dissociation of divalent metal-adducted sulfated N-glycans released from bovine thyroid stimulating hormone. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2013; 24:1798-806. [PMID: 23982932 PMCID: PMC3867818 DOI: 10.1007/s13361-013-0700-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Revised: 07/03/2013] [Accepted: 07/06/2013] [Indexed: 05/04/2023]
Abstract
Sulfated N-glycans released from bovine thyroid stimulating hormone (bTSH) were ionized with the divalent metal cations Ca(2+), Mg(2+), and Co by electrospray ionization (ESI). These metal-adducted species were subjected to infrared multiphoton dissociation (IRMPD) and electron capture dissociation (ECD) and the corresponding fragmentation patterns were compared. IRMPD generated extensive glycosidic and cross-ring cleavages, but most product ions suffered from sulfonate loss. Internal fragments were also observed, which complicated the spectra. ECD provided complementary structural information compared with IRMPD, and all observed product ions retained the sulfonate group, allowing sulfonate localization. To our knowledge, this work represents the first application of ECD towards metal-adducted sulfated N-glycans released from a glycoprotein. Due to the ability of IRMPD and ECD to provide complementary structural information, the combination of the two strategies is a promising and valuable tool for glycan structural characterization. The influence of different metal ions was also examined. Calcium adducts appeared to be the most promising species because of high sensitivity and ability to provide extensive structural information.
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Josipovic M, Persson G, Håkansson K, Damkjær S, Westman G, Bangsgaard J, Specht L, Aznar M. Deep Inspiration Breath-Hold Radiation Therapy for Advanced Stage Lung Cancer Is Feasible and Facilitates Lung Toxicity Reduction. Int J Radiat Oncol Biol Phys 2013. [DOI: 10.1016/j.ijrobp.2013.06.1435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rasmussen J, Vogelius I, Fischer M, Aznar M, Håkansson K, Persson G, Kristensen C, Bentzen S, Specht L. Prognostic Value of 18F-Fluorodeoxyglucose SUVmax in Head-and-Neck Cancer Depends on the Gross Tumor Volume. Int J Radiat Oncol Biol Phys 2013. [DOI: 10.1016/j.ijrobp.2013.06.1251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Hornum L, Hansen AJ, Tornehave D, Håkansson K, Fjording M, Bartels E, Søe NH, Bliddal H. THU0084 C5A and C5AR are Elevated in Joints of Rheumatoid and Psoriatic Arthritis Patients, and C5AR Blockade Attenuates Leukocyte Activation and Migration. Ann Rheum Dis 2013. [DOI: 10.1136/annrheumdis-2013-eular.612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Håkansson K, Specht L, Aznar M, Rasmussen J, Bentzen S, Vogelius I. OC-0430: A novel concept for history based evaluation of target dose distribution in multiple dose level treatment plans. Radiother Oncol 2013. [DOI: 10.1016/s0167-8140(15)32736-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Josipovic M, Damkjær S, Håkansson K, Aznar M, Bangsgaard J, Westman G, Fredberg Persson G. PO-0880: Voluntary deep inspiration breath hold for locally advanced lung cancer radiotherapy is feasible and reproducible. Radiother Oncol 2013. [DOI: 10.1016/s0167-8140(15)33186-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Rasmussen J, Vogelius I, Fischer M, Aznar M, Håkansson K, Kristensen C, Bentzen S, Specht L. PD-028: Suvmax and Gross Tumor Volume Associated with Failure After (Chemo-) Radiotherapy for HNSCC. Radiother Oncol 2013. [DOI: 10.1016/s0167-8140(15)34647-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Vogelius I, Håkansson K, Due A, Aznar M, Berthelsen A, Kristensen C, Specht L, Bentzen S. OC-021: Failure-Probability Driven Dose Painting. Radiother Oncol 2013. [DOI: 10.1016/s0167-8140(15)34640-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Håkansson K, Specht L, Rasmussen J, Aznar M, Bentzen S, Vogelius I. PO-069: Feasibility of Dose Painting to a Five Level Dose Prescription iñ a Dose Planning Study. Radiother Oncol 2013. [DOI: 10.1016/s0167-8140(15)34688-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Kornacki JR, Adamson JT, Håkansson K. Electron detachment dissociation of underivatized chloride-adducted oligosaccharides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:2031-2042. [PMID: 22911097 DOI: 10.1007/s13361-012-0459-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Revised: 07/22/2012] [Accepted: 07/23/2012] [Indexed: 06/01/2023]
Abstract
Chloride anion attachment has previously been shown to aid determination of saccharide anomeric configuration and generation of linkage information in negative ion post-source decay MALDI tandem mass spectrometry. Here, we employ electron detachment dissociation (EDD) and collision activated dissociation (CAD) for the structural characterization of underivatized oligosaccharides bearing a chloride ion adduct. Both neutral and sialylated oligosaccharides are examined, including maltoheptaose, an asialo biantennary glycan (NA2), disialylacto-N-tetraose (DSLNT), and two LS tetrasaccharides (LSTa and LSTb). Gas-phase chloride-adducted species are generated by negative ion mode electrospray ionization. EDD and CAD spectra of chloride-adducted oligosaccharides are compared to the corresponding spectra for doubly deprotonated species not containing a chloride anion to assess the role of chloride adduction in the stimulation of alternative fragmentation pathways and altered charge locations allowing detection of additional product ions. In all cases, EDD of singly chloridated and singly deprotonated species resulted in an increase in observed cross-ring cleavages, which are essential to providing saccharide linkage information. Glycosidic cleavages also increased in EDD of chloride-adducted oligosaccharides to reveal complementary structural information compared to traditional (non-chloride-assisted) EDD and CAD. Results indicate that chloride adduction is of interest in alternative anion activation methods such as EDD for oligosaccharide structural characterization.
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Hersberger KE, Håkansson K. Characterization of O-sulfopeptides by negative ion mode tandem mass spectrometry: superior performance of negative ion electron capture dissociation. Anal Chem 2012; 84:6370-7. [PMID: 22770115 DOI: 10.1021/ac301536r] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Positive ion mode collision-activated dissociation tandem mass spectrometry (CAD MS/MS) of O-sulfopeptides precludes determination of sulfonated sites due to facile proton-driven loss of the highly labile sulfonate groups. A previously proposed method for localizing peptide and protein O-sulfonation involves derivatization of nonsulfonated tyrosines followed by positive ion CAD MS/MS of the corresponding modified sulfopeptides for diagnostic sulfonate loss. This indirect method relies upon specific and complete derivatization of nonsulfonated tyrosines. Alternative MS/MS activation methods, including positive ion metastable atom-activated dissociation (MAD) and metal-assisted electron transfer dissociation (ETD) or electron capture dissociation (ECD) provide varying degrees of sulfonate retention. Sulfonate retention has also been reported following negative ion MAD and electron detachment dissociation (EDD), which also operates in negative ion mode in which sulfonate groups are less labile than in positive ion mode. However, an MS/MS activation technique that can effectively preserve sulfonate groups while providing extensive backbone fragmentation (translating to sequence information, including sulfonated sites) with little to no noninformative small molecule neutral loss has not previously been realized. Here, we report that negative ion CAD, EDD, and negative ETD (NETD) result in sulfonate retention mainly at higher charge states with varying degrees of fragmentation efficiency and sequence coverage. Similar to previous observations from CAD of sulfonated glycosaminoglycan anions, higher charge states translate to a higher probability of deprotonation at the sulfonate groups thus yielding charge-localized fragmentation without loss of the sulfonate groups. However, consequently, higher sulfonate retention comes at the price of lower sequence coverage in negative ion CAD. Fragmentation efficiency/sequence coverage averaged 19/6% and 33/20% in EDD and NETD, respectively, both of which are only applicable to multiply-charged anions. In contrast, the recently introduced negative ion ECD showed an average fragmentation efficiency of 69% and an average sequence coverage of 82% with complete sulfonate retention from singly- and doubly-deprotonated sulfopeptide anions.
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Håkansson K, Isidorsson T. Work Organizational Outcomes of the Use of Temporary Agency Workers. ORGANIZATION STUDIES 2012. [DOI: 10.1177/0170840612443456] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This article examines work organizational dynamics in workplaces using temporary agency workers. Previous research has principally either emphasized one effect, the division into core and periphery, or criticized this effect. This article contributes to a more nuanced analysis of how the work organization of user firms is affected by the use of temporary agency workers. Crucial factors influencing the outcome include: how agency workers are integrated into the work organization; the skills required for the work performed by agency workers; the duration of assignments; the induction time; and the access to competence development. Based on ten Swedish cases, our analysis shows that the use of temporary agency workers has three different outcomes: (1) The Core and Periphery outcome is in line with previous research on ‘the flexible firm’ whereby temporary agency workers are assigned simple work tasks and user firm employees perform advanced work tasks; (2) the All Core outcome entails using agency workers for the same advanced work tasks as user firm employees. Contradicting the theory of ‘the flexible firm’, our study shows that temporary agency workers contribute to functional flexibility; (3) the third outcome, All Periphery, occurs when the work organization is adapted to the use of low-skilled agency workers who are easily introduced into the workplace and easily terminated. However, adapting the work organization to the use of temporary agency workers also influences user firm employees, leading to deskilling and a deteriorated work organization for all workers at that workplace.
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Bonnett SA, Rath CM, Shareef AR, Joels JR, Chemler JA, Håkansson K, Reynolds K, Sherman DH. Acyl-CoA subunit selectivity in the pikromycin polyketide synthase PikAIV: steady-state kinetics and active-site occupancy analysis by FTICR-MS. ACTA ACUST UNITED AC 2012; 18:1075-81. [PMID: 21944746 DOI: 10.1016/j.chembiol.2011.07.016] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2011] [Revised: 06/23/2011] [Accepted: 07/04/2011] [Indexed: 10/17/2022]
Abstract
Polyketide natural products generated by type I modular polyketide synthases (PKSs) are vital components in our drug repertoire. To reprogram these biosynthetic assembly lines, we must first understand the steps that occur within the modular "black boxes." Herein, key steps of acyl-CoA extender unit selection are explored by in vitro biochemical analysis of the PikAIV PKS model system. Two complementary approaches are employed: a fluorescent-probe assay for steady-state kinetic analysis, and Fourier Transform Ion Cyclotron Resonance-mass spectrometry (FTICR-MS) to monitor active-site occupancy. Findings from five enzyme variants and four model substrates have enabled a model to be proposed involving catalysis based upon acyl-CoA substrate loading followed by differential rates of hydrolysis. These efforts suggest a strategy for future pathway engineering efforts using unnatural extender units with slow rates of hydrolytic off-loading from the acyltransferase domain.
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Song H, Håkansson K. Electron detachment dissociation and negative ion infrared multiphoton dissociation of electrosprayed intact proteins. Anal Chem 2011; 84:871-6. [PMID: 22175525 DOI: 10.1021/ac202909z] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In top-down proteomics, intact gaseous proteins are fragmented in a mass spectrometer by, e.g., electron capture dissociation (ECD) to obtain structural information. By far, most top-down approaches involve dissociation of protein cations. However, in electrospray ionization of phosphoproteins, the high acidity of phosphate may contribute to the formation of intramolecular hydrogen bonds or salt bridges, which influence subsequent fragmentation behavior. Other acidic proteins or proteins with regions containing multiple acidic residues may also be affected similarly. Negative ion mode, on the other hand, may enhance deprotonation and unfolding of multiply phosphorylated or highly acidic protein regions. Here, activated ion electron detachment dissociation (AI-EDD) and negative ion infrared multiphoton dissociation (IRMPD) were employed to investigate the fragmentation of intact proteins, including multiply phosphorylated β-casein, calmodulin, and glycosylated ribonuclease B. Compared to AI-ECD and positive ion IRMPD, AI-EDD and negative ion IRMPD provide complementary protein sequence information, particularly in regions with high acidity, including the multiply phosphorylated region of β-casein.
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Kalli A, Grigorean G, Håkansson K. Electron induced dissociation of singly deprotonated peptides. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2011; 22:2209-2221. [PMID: 21952776 DOI: 10.1007/s13361-011-0233-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/11/2011] [Accepted: 08/12/2011] [Indexed: 05/31/2023]
Abstract
Dissociation of singly charged species is more challenging compared with that of multiply charged precursor ions because singly charged ions are generally more stable. In collision activated dissociation (CAD), singly charged ions also gain less kinetic energy in a fixed electric field compared with multiply charged species. Furthermore, ion-electron and ion-ion reactions that frequently provide complementary and more extensive fragmentation compared with CAD typically require multiply charged precursor ions. Here, we investigate electron induced dissociation (EID) of singly deprotonated peptides and compare the EID fragmentation patterns with those observed in negative ion mode CAD. Fragmentation induced upon electron irradiation and collisional activation is not specific and results in the formation of a wide range of product ions, including b-, y-, a-, x-, c-, and z-type ions. Characteristic amino acid side chain losses are detected in both techniques. However, differences are also observed between EID and CAD spectra of the same species, including formation of odd-electron species not seen in CAD, in EID. Furthermore, EID frequently results in more extensive fragmentation compared with CAD. For modified peptides, EID resulted in retention of sulfonation and phosphorylation, allowing localization of the modification site. The observed differences are likely due to both vibrational and electronic excitation in EID, whereas only the former process occurs in CAD.
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Zhou W, Håkansson K. Structural Characterization of Carbohydrates by Fourier Transform Tandem Mass Spectrometry. CURR PROTEOMICS 2011; 8:297-308. [PMID: 22389641 PMCID: PMC3289259 DOI: 10.2174/157016411798220826] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fourier transform tandem mass spectrometry (MS/MS) provides high mass accuracy, high sensitivity, and analytical versatility and has therefore emerged as an indispensable tool for structural elucidation of biomolecules. Glycosylation is one of the most common posttranslational modifications, occurring in ~50% of proteins. However, due to the structural diversity of carbohydrates, arising from non-template driven biosynthesis, achievement of detailed structural insight is highly challenging. This review briefly discusses carbohydrate sample preparation and ionization methods, and highlights recent developments in alternative high-resolution MS/MS strategies, including infrared multiphoton dissociation (IRMPD), electron capture dissociation (ECD), and electron detachment dissociation (EDD), for carbohydrates with a focus on glycans and proteoglycans from mammalian glycoproteins.
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Zhou W, Håkansson K. Electron detachment dissociation of fluorescently labeled sialylated oligosaccharides. Electrophoresis 2011; 32:3526-35. [PMID: 22120881 DOI: 10.1002/elps.201100327] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2011] [Revised: 08/11/2011] [Accepted: 09/05/2011] [Indexed: 01/07/2023]
Abstract
We explored the application of electron detachment dissociation (EDD) and infrared multiphoton dissociation (IRMPD) tandem mass spectrometry to fluorescently labeled sialylated oligosaccharides. Standard sialylated oligosaccharides and a sialylated N-linked glycan released from human transferrin were investigated. EDD yielded extensive glycosidic cleavages and cross-ring cleavages in all cases studied, consistently providing complementary structural information compared with infrared multiphoton dissociation. Neutral losses and satellite ions such as C-2H ions were also observed following EDD. In addition, we examined the influence of different fluorescent labels. The acidic label 2-aminobenzoic acid (2-AA) enhanced signal abundance in negative-ion mode. However, few cross-ring fragments were observed for 2-AA-labeled oligosaccharides. The neutral label 2-aminobenzamide (2-AB) resulted in more cross-ring cleavages compared with 2-AA-labeled species, but not as extensive fragmentation as for native oligosaccharides, likely resulting from altered negative charge locations from introduction of the fluorescent tag.
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Rath CM, Janto B, Earl J, Ahmed A, Hu FZ, Hiller L, Dahlgren M, Kreft R, Yu F, Wolff JJ, Kweon HK, Christiansen MA, Håkansson K, Williams RM, Ehrlich GD, Sherman DH. Meta-omic characterization of the marine invertebrate microbial consortium that produces the chemotherapeutic natural product ET-743. ACS Chem Biol 2011; 6:1244-56. [PMID: 21875091 DOI: 10.1021/cb200244t] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In many macroorganisms, the ultimate source of potent biologically active natural products has remained elusive due to an inability to identify and culture the producing symbiotic microorganisms. As a model system for developing a meta-omic approach to identify and characterize natural product pathways from invertebrate-derived microbial consortia, we chose to investigate the ET-743 (Yondelis) biosynthetic pathway. This molecule is an approved anticancer agent obtained in low abundance (10(-4)-10(-5) % w/w) from the tunicate Ecteinascidia turbinata and is generated in suitable quantities for clinical use by a lengthy semisynthetic process. On the basis of structural similarities to three bacterial secondary metabolites, we hypothesized that ET-743 is the product of a marine bacterial symbiont. Using metagenomic sequencing of total DNA from the tunicate/microbial consortium, we targeted and assembled a 35 kb contig containing 25 genes that comprise the core of the NRPS biosynthetic pathway for this valuable anticancer agent. Rigorous sequence analysis based on codon usage of two large unlinked contigs suggests that Candidatus Endoecteinascidia frumentensis produces the ET-743 metabolite. Subsequent metaproteomic analysis confirmed expression of three key biosynthetic proteins. Moreover, the predicted activity of an enzyme for assembly of the tetrahydroisoquinoline core of ET-743 was verified in vitro. This work provides a foundation for direct production of the drug and new analogues through metabolic engineering. We expect that the interdisciplinary approach described is applicable to diverse host-symbiont systems that generate valuable natural products for drug discovery and development.
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Yoo HJ, Wang N, Zhuang S, Song H, Håkansson K. Negative-Ion Electron Capture Dissociation: Radical-Driven Fragmentation of Charge-Increased Gaseous Peptide Anions. J Am Chem Soc 2011; 133:16790-3. [DOI: 10.1021/ja207736y] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Ding Y, Rath CM, Bolduc KL, Håkansson K, Sherman DH. Chemoenzymatic synthesis of cryptophycin anticancer agents by an ester bond-forming non-ribosomal peptide synthetase module. J Am Chem Soc 2011; 133:14492-5. [PMID: 21823639 DOI: 10.1021/ja204716f] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cryptophycins (Crp) are a group of cyanobacterial depsipeptides with activity against drug-resistant tumors. Although they have been shown to be promising, further efforts are required to return these highly potent compounds to the clinic through a new generation of analogues with improved medicinal properties. Herein, we report a chemosynthetic route relying on the multifunctional enzyme CrpD-M2 that incorporates a 2-hydroxy acid moiety (unit D) into Crp analogues. CrpD-M2 is a unique non-ribosomal peptide synthetase (NRPS) module comprised of condensation-adenylation-ketoreduction-thiolation (C-A-KR-T) domains. We interrogated A-domain 2-keto and 2-hydroxy acid activation and loading, and KR domain activity in the presence of NADPH and NADH. The resulting 2-hydroxy acid was elongated with three synthetic Crp chain elongation intermediate analogues through ester bond formation catalyzed by CrpD-M2 C domain. Finally, the enzyme-bound seco-Crp products were macrolactonized by the Crp thioesterase. Analysis of these sequential steps was enabled through LC-FTICR-MS of enzyme-bound intermediates and products. This novel chemoenzymatic synthesis of Crp involves four sequential catalytic steps leading to the incorporation of a 2-hydroxy acid moiety in the final chain elongation intermediate. The presented work constitutes the first example where a NRPS-embedded KR domain is employed for assembly of a fully elaborated natural product, and serves as a proof-of-principle for chemoenzymatic synthesis of new Crp analogues.
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Buchholz TJ, Rath CM, Lopanik NB, Gardner NP, Håkansson K, Sherman DH. Polyketide β-branching in bryostatin biosynthesis: identification of surrogate acetyl-ACP donors for BryR, an HMG-ACP synthase. ACTA ACUST UNITED AC 2011; 17:1092-100. [PMID: 21035732 DOI: 10.1016/j.chembiol.2010.08.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 08/10/2010] [Accepted: 08/17/2010] [Indexed: 10/18/2022]
Abstract
In vitro analysis of natural product biosynthetic gene products isolated from unculturable symbiotic bacteria is necessary to probe the functionalities of these enzymes. Herein, we report the biochemical characterization of BryR, the 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase (HMGS) homolog implicated in β-branching at C13 and C21 of the core ring system from the bryostatin metabolic pathway (Bry). We confirmed the activity of BryR using two complementary methods, radio-SDS PAGE, and Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS). The activity of BryR depended on pairing of the native acetoacetyl-BryM3 acceptor acyl carrier protein (ACP) with an appropriate donor acetyl-ACP from a heterologous HMGS cassette. Additionally, the ability of BryR to discriminate between various ACPs was assessed using a surface plasmon resonance (SPR)-based protein-protein binding assay. Our data suggest that specificity for a protein-bound acyl group is a distinguishing feature between HMGS homologs found in PKS or PKS/NRPS biosynthetic pathways and those of primary metabolism. These findings reveal an important example of molecular recognition between protein components that are essential for biosynthetic fidelity in natural product assembly and modification.
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Yoo HJ, Håkansson K. Determination of Phospholipid Regiochemistry by Ag(I) Adduction and Tandem Mass Spectrometry. Anal Chem 2011; 83:1275-83. [DOI: 10.1021/ac102167q] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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