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  1. Article: Characterization of Streptococcus pneumoniae thymidylate kinase: steady-state kinetics of the forward reaction and isothermal titration calorimetry.

    Petit, Chantal M / Koretke, Kristin K

    The Biochemical journal

    2001  Volume 363, Issue Pt 3, Page(s) 825–831

    Abstract: Thymidylate kinase (TMK) catalyses the phosphorylation of dTMP to form dTDP in both the de novo and salvage pathways of dTTP synthesis. The tmk gene from the bacterial pathogen Streptococcus pneumoniae was identified. The gene, encoding a 212-amino-acid ... ...

    Abstract Thymidylate kinase (TMK) catalyses the phosphorylation of dTMP to form dTDP in both the de novo and salvage pathways of dTTP synthesis. The tmk gene from the bacterial pathogen Streptococcus pneumoniae was identified. The gene, encoding a 212-amino-acid polypeptide (23352 Da), was cloned and overexpressed in Escherichia coli with an N-terminal hexahistidine tag. The enzyme was purified to homogeneity, and characterized in the forward reaction. The pH profile of TMK indicates that its activity is optimal at pH 8.5. The substrate specificity of the enzyme was examined; it was found that not only ATP, but also dATP and to a lesser extent CTP, could act as phosphate donors, and dTMP and dUMP could serve as phosphate acceptors. Furthermore, AZT-MP (3'-azido-3'-deoxythymidine 5'-monophosphate) was shown not to be a substrate for S. pneumoniae TMK. Steady-state kinetics and inhibition studies with adenosine 5'-[beta-thio]diphosphate and dTDP in addition to isothermal titration calorimetry were performed. The data showed that binding follows an ordered pathway, in which ATP binds first with a K(m) of 235 +/- 46 microM and a K(d) of 116 +/- 3 microM, and dTMP binds secondly with a K(m) of 66 +/- 12 microM and a K(d) of 53 +/- 2 microM.
    MeSH term(s) Adenosine Triphosphate/metabolism ; Amino Acid Sequence ; Calorimetry ; Cytidine Triphosphate/metabolism ; Deoxyuracil Nucleotides/metabolism ; Escherichia coli ; Hydrogen-Ion Concentration ; Molecular Sequence Data ; Molecular Weight ; Nucleoside-Phosphate Kinase/metabolism ; Phosphorylation ; Streptococcus pneumoniae/enzymology ; Substrate Specificity ; Thymine Nucleotides/metabolism
    Chemical Substances Deoxyuracil Nucleotides ; Thymine Nucleotides ; thymidine 3',5'-diphosphate (2863-04-9) ; Cytidine Triphosphate (65-47-4) ; Adenosine Triphosphate (8L70Q75FXE) ; 2'-deoxyuridylic acid (964-26-1) ; Nucleoside-Phosphate Kinase (EC 2.7.4.4) ; dTMP kinase (EC 2.7.4.9)
    Language English
    Publishing date 2001-02-06
    Publishing country England
    Document type Journal Article
    ZDB-ID 2969-5
    ISSN 1470-8728 ; 0264-6021 ; 0006-2936 ; 0306-3275
    ISSN (online) 1470-8728
    ISSN 0264-6021 ; 0006-2936 ; 0306-3275
    DOI 10.1042/0264-6021:3630825
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  2. Article: Intravenous Pharmacokinetics, Local Tolerability, and Hemolysis of an SBE7-β-Cyclodextrin Formulation of the Neurokinin-1 Receptor Antagonist Vestipitant.

    Brigandi, Richard A / Russ, Steven F / Petit, Chantal / Johnson, Brendan / Croy, Scott / Hodsman, Peter / Muller, Fran

    Clinical pharmacology in drug development

    2015  Volume 4, Issue 2, Page(s) 130–136

    Abstract: Vestipitant is a potent and selective neurokinin 1 (NK-1) receptor antagonist that was investigated as a potential treatment for post-operative nausea and vomiting (PONV). A previous mannitol-based formulation of vestipitant was associated with hemolytic ...

    Abstract Vestipitant is a potent and selective neurokinin 1 (NK-1) receptor antagonist that was investigated as a potential treatment for post-operative nausea and vomiting (PONV). A previous mannitol-based formulation of vestipitant was associated with hemolytic activity in preclinical studies. In an effort to reduce the hemolytic potential and develop an IV formulation of vestipitant that could be administered more rapidly, an IV formulation containing sulfobutylether-7-beta-cyclodextrin (SBE7-β-CD, Captisol™) was developed and tested in a phase 1 clinical study. This was a randomized, single-blind (subjects and investigator-blinded, sponsor-unblinded), placebo controlled, dose escalation study in healthy subjects in which 7 cohorts of 8 subjects per cohort received SBE7-β-CD -based vestipitant (2 mg/mL) or placebo (saline) in a 3:1 ratio (active:placebo) at different doses and infusion rates. The results demonstrated the ability to infuse up to 48 mg vestipitant in a 2 mg/mL formulation over 30 seconds with no evidence of hemolytic effects. Cohorts of subjects at lower doses and longer infusion duration (>1 minute) reported more AEs related to the infusion site than those at the higher doses and faster infusion rates.
    Language English
    Publishing date 2015-03
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2649010-9
    ISSN 2160-7648 ; 2160-763X
    ISSN (online) 2160-7648
    ISSN 2160-763X
    DOI 10.1002/cpdd.128
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  3. Article ; Online: [(124)I]FIAU: Human dosimetry and infection imaging in patients with suspected prosthetic joint infection.

    Zhang, Xiaoyan M / Zhang, Halle H / McLeroth, Patrick / Berkowitz, Richard D / Mont, Michael A / Stabin, Michael G / Siegel, Barry A / Alavi, Abass / Barnett, T Marc / Gelb, Jeffrey / Petit, Chantal / Spaltro, John / Cho, Steve Y / Pomper, Martin G / Conklin, James J / Bettegowda, Chetan / Saha, Saurabh

    Nuclear medicine and biology

    2016  Volume 43, Issue 5, Page(s) 273–279

    Abstract: Introduction: Fialuridine (FIAU) is a nucleoside analog that is a substrate for bacterial thymidine kinase (TK). Once phosphorylated by TK, [(124)I]FIAU becomes trapped within bacteria and can be detected with positron emission tomography/computed ... ...

    Abstract Introduction: Fialuridine (FIAU) is a nucleoside analog that is a substrate for bacterial thymidine kinase (TK). Once phosphorylated by TK, [(124)I]FIAU becomes trapped within bacteria and can be detected with positron emission tomography/computed tomography (PET/CT). [(124)I]FIAU PET/CT has been shown to detect bacteria in patients with musculoskeletal bacterial infections. Accurate diagnosis of prosthetic joint infections (PJIs) has proven challenging because of the lack of a well-validated reference. In the current study, we assessed biodistribution and dosimetry of [(124)I]FIAU, and investigated whether [(124)I]FIAU PET/CT can diagnose PJIs with acceptable accuracy.
    Methods: To assess biodistribution and dosimetry, six subjects with suspected hip or knee PJI and six healthy subjects underwent serial PET/CT after being dosed with 74MBq (2mCi) [(124)I]FIAU intravenously (IV). Estimated radiation doses were calculated with the OLINDA/EXM software. To determine accuracy of [(124)I]FIAU, 22 subjects with suspected hip or knee PJI were scanned at 2-6 and 24-30h post IV injection of 185MBq (5mCi) [(124)I]FIAU. Images were interpreted by a single reader blinded to clinical information. Representative cases were reviewed by 3 additional readers. The utility of [(124)I]FIAU to detect PJIs was assessed based on the correlation of the patient's infection status with imaging results as determined by an independent adjudication board (IAB).
    Results: The kidney, liver, spleen, and urinary bladder received the highest radiation doses of [(124)I]FIAU. The effective dose was 0.16 to 0.20mSv/MBq and doses to most organs ranged from 0.11 to 0.76mGy/MBq. PET image quality obtained from PJI patients was confounded by metal artifacts from the prostheses and pronounced FIAU uptake in muscle. Consequently, a correlation with infection status and imaging results could not be established.
    Conclusions: [(124)I]FIAU was well-tolerated in healthy volunteers and subjects with suspected PJI, and had acceptable dosimetry. However, the utility of [(124)I]FIAU for the clinical detection of PJIs is limited by poor image quality and low specificity.
    MeSH term(s) Adult ; Arabinofuranosyluracil/adverse effects ; Arabinofuranosyluracil/analogs & derivatives ; Arabinofuranosyluracil/pharmacokinetics ; Female ; Humans ; Joint Diseases/diagnostic imaging ; Joint Diseases/metabolism ; Male ; Positron Emission Tomography Computed Tomography/adverse effects ; Positron Emission Tomography Computed Tomography/methods ; Prosthesis-Related Infections/diagnostic imaging ; Prosthesis-Related Infections/metabolism ; Radiometry ; Safety ; Tissue Distribution
    Chemical Substances Arabinofuranosyluracil (3083-77-0) ; fialuridine (53T7IN77LC)
    Language English
    Publishing date 2016-05
    Publishing country United States
    Document type Clinical Trial, Phase I ; Clinical Trial, Phase II ; Journal Article
    ZDB-ID 1138098-6
    ISSN 1872-9614 ; 0883-2897 ; 0969-8051
    ISSN (online) 1872-9614
    ISSN 0883-2897 ; 0969-8051
    DOI 10.1016/j.nucmedbio.2016.01.004
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  4. Article: Purification and characterization of YihA, an essential GTP-binding protein from Escherichia coli.

    Lehoux, Isabelle E / Mazzulla, Marie J / Baker, Audrey / Petit, Chantal M

    Protein expression and purification

    2003  Volume 30, Issue 2, Page(s) 203–209

    Abstract: YihA has previously been characterized as an essential gene of unknown function in both Escherichia coli and Bacillus subtilis. It is conserved in bacteria and represents an attractive target for the discovery of new antibiotics. YihA encodes a putative ... ...

    Abstract YihA has previously been characterized as an essential gene of unknown function in both Escherichia coli and Bacillus subtilis. It is conserved in bacteria and represents an attractive target for the discovery of new antibiotics. YihA encodes a putative GTP-binding protein. We have cloned and overexpressed the gene encoding E. coli YihA and initiated biochemical studies as a first step towards understanding its biological function. We showed by circular dichroism that the purified protein has a secondary structure typical of most GTP-binding proteins. It binds guanine nucleotides specifically, as demonstrated by fluorescence resonance energy transfer between 2'-(or-3')-O-(N-methylanthraniloyl) nucleotides (mant-nucleotides) and the tryptophans of YihA. The K(d) values for GDP and GTP were determined by competition with 2'-(or-3')-O-(N-methylanthraniloyl) GDP to be 3 and 27 microM, respectively. Using mutants of YihA we show that nucleotide binding occurs at the putative GTP-binding domain predicted from the primary sequence.
    MeSH term(s) Amino Acid Sequence ; Circular Dichroism ; Cloning, Molecular ; Escherichia coli/chemistry ; Escherichia coli/genetics ; Escherichia coli Proteins/chemistry ; Escherichia coli Proteins/genetics ; Escherichia coli Proteins/isolation & purification ; Escherichia coli Proteins/metabolism ; GTP-Binding Proteins/chemistry ; GTP-Binding Proteins/genetics ; GTP-Binding Proteins/isolation & purification ; GTP-Binding Proteins/metabolism ; Guanosine Diphosphate/metabolism ; Guanosine Triphosphate/metabolism ; Hot Temperature ; Molecular Sequence Data ; Mutagenesis, Site-Directed ; Protein Denaturation ; Sequence Alignment
    Chemical Substances Escherichia coli Proteins ; Guanosine Diphosphate (146-91-8) ; Guanosine Triphosphate (86-01-1) ; GTP-Binding Proteins (EC 3.6.1.-) ; YihA protein, E coli (EC 3.6.1.-)
    Language English
    Publishing date 2003-07-23
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1055455-5
    ISSN 1096-0279 ; 1046-5928
    ISSN (online) 1096-0279
    ISSN 1046-5928
    DOI 10.1016/s1046-5928(03)00107-4
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  5. Article: Mechanism of time-dependent inhibition of polypeptide deformylase by actinonin.

    Van Aller, Glenn S / Nandigama, Ravi / Petit, Chantal M / DeWolf, Walt E / Quinn, Chad J / Aubart, Kelly M / Zalacain, Magdalena / Christensen, Siegfried B / Copeland, Robert A / Lai, Zhihong

    Biochemistry

    2005  Volume 44, Issue 1, Page(s) 253–260

    Abstract: Polypeptide deformylase (PDF) is an essential bacterial metalloenzyme responsible for the removal of the N-formyl group from the N-terminal methionine of nascent polypeptides. Inhibition of bacterial PDF enzymes by actinonin, a naturally occurring ... ...

    Abstract Polypeptide deformylase (PDF) is an essential bacterial metalloenzyme responsible for the removal of the N-formyl group from the N-terminal methionine of nascent polypeptides. Inhibition of bacterial PDF enzymes by actinonin, a naturally occurring antibacterial agent, has been characterized using steady-state and transient kinetic methods. Slow binding of actinonin to these enzymes is observed under steady-state conditions. Progress curve analysis is consistent with a two-step binding mechanism, in which tightening of the initial encounter complex (EI) results in a final complex (EI*) with an extremely slow, but observable, off-rate (t(1/2) for inhibitor dissociation >or=0.77 days). Stopped-flow measurement of PDF fluorescence confirms formation of EI and provides a direct measurement of the association rate. Rapid dilution studies establish that the potency of actinonin is enhanced by more than 2000-fold upon tightening of EI to form EI*, from K(i) = 530 nM (EI) to Ki*<or= 0.23 nM (EI*). In sharp contrast, the previously reported small molecule PDF inhibitor, SB-543668, is a competitive, readily reversible inhibitor (t(1/2) for dissociation = 2.8 s). In addition, we demonstrate that BB-3497 is also a time-dependent inhibitor of PDF with an extremely slow off-rate. The two-step inhibition model detailed herein for the inhibition of Staphylococcus aureus PDF by actinonin and BB-3497 is consistent with a recent report on the time-dependent inhibition of Escherichia coli PDF by a macrocyclic peptidomimetic inhibitor [Ngugen, K. T., et al. (2004) Bioorg. Chem. 32, 178-191]. This study substantially extends our understanding of PDF inhibition and may facilitate the development of novel antibiotics.<br />
    MeSH term(s) Amidohydrolases/antagonists & inhibitors ; Amidohydrolases/chemistry ; Anti-Bacterial Agents/pharmacology ; Hydroxamic Acids/chemistry ; Hydroxamic Acids/pharmacology ; Kinetics ; Protein Binding ; Staphylococcus aureus/enzymology
    Chemical Substances Anti-Bacterial Agents ; Hydroxamic Acids ; Amidohydrolases (EC 3.5.-) ; peptide deformylase (EC 3.5.1.88) ; actinonin (P18SPA8N0K)
    Language English
    Publishing date 2005-01-11
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1108-3
    ISSN 1520-4995 ; 0006-2960
    ISSN (online) 1520-4995
    ISSN 0006-2960
    DOI 10.1021/bi048632b
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  6. Article: Characterization of Streptococcus pneumoniae TrmD, a tRNA methyltransferase essential for growth.

    O'Dwyer, Karen / Watts, Joseph M / Biswas, Sanjoy / Ambrad, Jennifer / Barber, Michael / Brulé, Hervé / Petit, Chantal / Holmes, David J / Zalacain, Magdalena / Holmes, Walter M

    Journal of bacteriology

    2004  Volume 186, Issue 8, Page(s) 2346–2354

    Abstract: Down-regulation of expression of trmD, encoding the enzyme tRNA (guanosine-1)-methyltransferase, has shown that this gene is essential for growth of Streptococcus pneumoniae. The S. pneumoniae trmD gene has been isolated and expressed in Escherichia coli ...

    Abstract Down-regulation of expression of trmD, encoding the enzyme tRNA (guanosine-1)-methyltransferase, has shown that this gene is essential for growth of Streptococcus pneumoniae. The S. pneumoniae trmD gene has been isolated and expressed in Escherichia coli by using a His-tagged T7 expression vector. Recombinant protein has been purified, and its catalytic and physical properties have been characterized. The native enzyme displays a molecular mass of approximately 65,000 Da, suggesting that streptococcal TrmD is a dimer of two identical subunits. In fact, this characteristic can be extended to several other TrmD orthologs, including E. coli TrmD. Kinetic studies show that the streptococcal enzyme utilizes a sequential mechanism. Binding of tRNA by gel mobility shift assays gives a dissociation constant of 22 nM for one of its substrates, tRNA(Leu)(CAG). Other heterologous nonsubstrate tRNA species, like, tRNA (Thr)(GGT), tRNA(Phe), and tRNA (Ala)(TGC), bind the enzyme with similar affinities, suggesting that tRNA specificity is achieved via a postbinding event(s).
    MeSH term(s) Amino Acid Sequence ; Cloning, Molecular ; Escherichia coli/metabolism ; Kinetics ; Molecular Sequence Data ; Molecular Weight ; Operon ; RNA, Transfer/chemical synthesis ; RNA, Transfer/metabolism ; Recombinant Proteins/metabolism ; Sequence Alignment ; Streptococcus pneumoniae/enzymology ; Streptococcus pneumoniae/growth & development ; tRNA Methyltransferases/chemistry ; tRNA Methyltransferases/genetics ; tRNA Methyltransferases/metabolism
    Chemical Substances Recombinant Proteins ; RNA, Transfer (9014-25-9) ; tRNA Methyltransferases (EC 2.1.1.-)
    Language English
    Publishing date 2004-02-17
    Publishing country United States
    Document type Comparative Study ; Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 2968-3
    ISSN 1098-5530 ; 0021-9193
    ISSN (online) 1098-5530
    ISSN 0021-9193
    DOI 10.1128/JB.186.8.2346-2354.2004
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  7. Article: Structural variation and inhibitor binding in polypeptide deformylase from four different bacterial species.

    Smith, Kathrine J / Petit, Chantal M / Aubart, Kelly / Smyth, Martin / McManus, Edward / Jones, Jo / Fosberry, Andrew / Lewis, Ceri / Lonetto, Michael / Christensen, Siegfried B

    Protein science : a publication of the Protein Society

    2003  Volume 12, Issue 2, Page(s) 349–360

    Abstract: Polypeptide deformylase (PDF) catalyzes the deformylation of polypeptide chains in bacteria. It is essential for bacterial cell viability and is a potential antibacterial drug target. Here, we report the crystal structures of polypeptide deformylase from ...

    Abstract Polypeptide deformylase (PDF) catalyzes the deformylation of polypeptide chains in bacteria. It is essential for bacterial cell viability and is a potential antibacterial drug target. Here, we report the crystal structures of polypeptide deformylase from four different species of bacteria: Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae, and Escherichia coli. Comparison of these four structures reveals significant overall differences between the two Gram-negative species (E. coli and H. influenzae) and the two Gram-positive species (S. pneumoniae and S. aureus). Despite these differences and low overall sequence identity, the S1' pocket of PDF is well conserved among the four enzymes studied. We also describe the binding of nonpeptidic inhibitor molecules SB-485345, SB-543668, and SB-505684 to both S. pneumoniae and E. coli PDF. Comparison of these structures shows similar binding interactions with both Gram-negative and Gram-positive species. Understanding the similarities and subtle differences in active site structure between species will help to design broad-spectrum polypeptide deformylase inhibitor molecules.
    MeSH term(s) Amidohydrolases ; Amino Acid Sequence ; Aminopeptidases/antagonists & inhibitors ; Aminopeptidases/chemistry ; Aminopeptidases/metabolism ; Bacterial Proteins/antagonists & inhibitors ; Bacterial Proteins/chemistry ; Bacterial Proteins/metabolism ; Binding Sites ; Crystallography, X-Ray ; Enzyme Inhibitors/chemistry ; Enzyme Inhibitors/metabolism ; Enzyme Inhibitors/pharmacology ; Escherichia coli/drug effects ; Escherichia coli/enzymology ; Haemophilus influenzae/drug effects ; Haemophilus influenzae/enzymology ; Kinetics ; Microbial Sensitivity Tests ; Models, Molecular ; Molecular Sequence Data ; Peptides ; Protein Binding ; Protein Conformation ; Sequence Homology, Amino Acid ; Staphylococcus aureus/drug effects ; Staphylococcus aureus/enzymology ; Streptococcus pneumoniae/drug effects ; Streptococcus pneumoniae/enzymology
    Chemical Substances Bacterial Proteins ; Enzyme Inhibitors ; Peptides ; Aminopeptidases (EC 3.4.11.-) ; Amidohydrolases (EC 3.5.-) ; peptide deformylase (EC 3.5.1.88)
    Language English
    Publishing date 2003-02
    Publishing country United States
    Document type Comparative Study ; Journal Article
    ZDB-ID 1106283-6
    ISSN 1469-896X ; 0961-8368
    ISSN (online) 1469-896X
    ISSN 0961-8368
    DOI 10.1110/ps.0229303
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