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  • 1
    Electronic Resource
    Electronic Resource
    Growth and division of Streptococcus pneumoniae: localization of the high molecular weight penicillin-binding proteins during the cell cycle (2003)
    Oxford, UK : Blackwell Publishing Ltd.
    Molecular microbiology 50 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The bacterial peptidoglycan, the main component of the cell wall, is synthesized by the penicillin-binding proteins (PBPs). We used immunofluorescence microscopy to determine the cellular localization of all the high molecular weight PBPs of the human pathogen Streptococcus pneumoniae, for a wild type and for several PBP-deficient strains. Progression through the cell cycle was investigated by the simultaneous labelling of DNA and the FtsZ protein. Our main findings are: (i) the temporal dissociation of cell wall synthesis, inferred by the localization of PBP2x and PBP1a, from the constriction of the FtsZ-ring; (ii) the localization of PBP2b and PBP2a at duplicated equatorial sites indicating the existence of peripheral peptidoglycan synthesis, which implies a similarity between the mechanism of cell division in bacilli and streptococci; (iii) the abnormal localization of some class A PBPs in PBP-defective mutants which may explain the apparent redundancy of these proteins in S. pneumoniae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03767.x
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  • 2
    Electronic Resource
    Electronic Resource
    In vitro reconstitution of a trimeric complex of DivIB, DivIC and FtsL, and their transient co-localization at the division site in Streptococcus pneumoniae (2005)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: DivIB, DivIC and FtsL are bacterial proteins essential for cell division, which show interdependencies for their stabilities and localization. We have reconstituted in vitro a trimeric complex consisting of the recombinant extracellular domains of the three proteins from Streptococcus pneumoniae. The extracellular domain of DivIB was found to associate with a heterodimer of those of DivIC and FtsL. The heterodimerization of DivIC and FtsL was artificially constrained by fusion with interacting coiled-coils. Immunofluorescence experiments showed that DivIC is always localized at mid-cell, in contrast to DivIB and FtsL, which are co-localized with DivIC only during septation. Taken together, our data suggest that assembly of the trimeric complex DivIB/DivIC/FtsL is regulated during the cell cycle through controlled formation of the DivIC/FtsL heterodimer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2004.04408.x
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  • 3
    Electronic Resource
    Electronic Resource
    The d,d-carboxypeptidase PBP3 organizes the division process of Streptococcus pneumoniae (2004)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 51 (2004), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Bacterial division requires the co-ordination of membrane invagination, driven by the constriction of the FtsZ-ring, and concomitant cell wall synthesis, performed by the high-molecular-weight penicillin-binding proteins (HMW PBPs). Using immunofluorescence techniques, we show in Streptococcus pneumoniae that this co-ordination requires PBP3, a d,d-carboxypeptidase that degrades the substrate of the HMW PBPs. In a mutant deprived of PBP3, the apparent rings of HMW PBPs and that of FtsZ are no longer co-localized. In wild-type cells, PBP3 is absent at the future division site and present over the rest of the cell surface, implying that the localization of the HMW PBPs at mid-cell depends on the availability of their substrate. FtsW, a putative translocase of the substrate of the PBPs, forms an apparent ring that is co-localized with the septal HMW PBPs throughout the cell cycle of wild-type cells. In particular, the constriction of the FtsW-ring occurs after that of the FtsZ-ring, with the same delay as the constriction of the septal PBP-rings. However, in the absence of PBP3, FtsW remains co-localized with FtsZ in contrast to the HMW PBPs. Our work reveals an unexpected complexity in the relationships between the division proteins. The consequences of the absence of PBP3 indicate that the peptidoglycan composition is central to the co-ordination of the division process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03953.x
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  • 4
    Electronic Resource
    Electronic Resource
    Methionine-321 in the C-terminal α-helix of catabolic ornithine carbamoyltransferase from Pseudomonas aeruginosa is important for positive homotropic cooperativity (1994)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 124 (1994), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Pseudomonas aeruginosa has a pair of distinct ornithine carbamoyltransferases. The anabolic ornithine carbamoyltransferase encoded by the argF gene catalyzes the formation of citrulline from ornithine and carbamoylphosphate. The catabolic ornithine carbamoyltransferase encoded by the arcB gene promotes the reverse reaction in vivo; although this enzyme can be assayed in vitro for citrulline synthesis, its unidirectionality in vivo is determined by its high concentration at half maximum velocity for carbamoylphosphate ([S]0.5) and high cooperativity toward this substrate. We have mutant forms of catabolic ornithine carbamoyltransferase catalyzing the anabolic reaction in vivo. The corresponding arcB mutant alleles on a multicopy plasmid specifically suppressed an argF mutation of P. aeruginosa. Two new mutant enzymes were obtained. When methionine 321 was replaced by isoleucine, the mutant enzyme showed loss of homotropic cooperativity at physiological carbamoylphosphate concentrations. Substitution of glutamate 105 by lysine resulted in a partial loss of the sigmoidal response to increasing carbamoylphosphate concentrations. However, both mutant enzymes were still sensitive to the allosteric activator AMP and to the inhibitor spermidine. These results indicate that at least two residues of catabolic ornithine carbamoyltransferase are critically involved in positive carbamoylphisphate cooperativity: glutamate 105 (previously known to be important) and methionine 321. Mutational changes in either amino acid will affect the geometry of helix H2, which contains several residues required for carbamoylphosphate binding.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1994.tb07317.x
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  • 5
    Electronic Resource
    Electronic Resource
    Expression, purification, crystallization and preliminary X-ray analysis of the ι-carrageenase from Alteromonas fortis (2000)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 766-768 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: This is the first crystallization report of a glycoside hydrolase which belongs to family 82. A recombinant form of His-tagged ι-carrageenase from Alteromonas fortis was expressed, purified and crystallized. Crystals were obtained by the vapour-diffusion method using polyethylene glycol (MW = 6000) as a precipitant. They belong to space group P21, with unit-cell parameters a = 56.75, b = 91.04, c = 125.01 Å, β = 93.41°. The unit cell contains two molecules in the asymmetric unit related by a non-crystallographic twofold axis. Crystals diffracted to 2.0 Å resolution on a synchrotron beamline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444900004844
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  • 6
    Electronic Resource
    Electronic Resource
    Crystallization and preliminary X-ray diffraction analysis of the regulatory subunit of human protein kinase CK2 (1999)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 55 (1999), S. 895-897 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Protein kinase CK2 is a tetramer composed of two α catalytic subunits and two β regulatory subunits. A C-terminal truncated form of the β subunit has been overproduced in Escherichia coli and purified to homogeneity. Two crystal forms of the truncated protein which diffract to at least 2 Å resolution have been obtained. Form I belongs to the monoclinic space group P21, with unit-cell parameters a = 49.9, b = 92.9, c = 53.7 Å, β = 96.3°, and yields plate-like crystals. Form II belongs to the tetragonal space group P42212, with unit-cell parameters a = 132.19, b = 132.19, c = 63.79 Å, and produces rod-shaped crystals. Both crystal forms have a functional dimer in the crystal asymmetric unit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444998016680
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  • 7
    Electronic Resource
    Electronic Resource
    X-ray Structure of the ZnII β-Lactamase from Bacteroides fragilis in an Orthorhombic Crystal Form (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 47-57 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: β-Lactamases are extracellular or periplasmic bacterial enzymes which confer resistance to β-lactam antibiotics. On the basis of their catalytic mechanisms, they can be divided into two major groups: active-site serine enzymes (classes A, C and D) and the ZnII enzymes (class B). The first crystal structure of a class B enzyme, the metallo-β-lactamase from Bacillus cereus, has been solved at 2.5 Å resolution [Carfi, Pares, Duée, Galleni, Duez, Frère & Dideberg (1995). EMBO J. 14, 4914–4921]. Recently, the crystal structure of the metallo-β-lactamase from Bacteroides fragilis has been determined in a tetragonal space group [Concha, Rasmussen, Bush & Herzberg (1996). Structure, 4, 823–836]. The structure of the metallo-β-lactamase from B. fragilis in an orthorhombic crystal form at 2.0 Å resolution is reported here. The final crystallographic R is 0.196 for all the 32 501 observed reflections in the range 10–2.0 Å. The refined model includes 458 residues, 437 water molecules, four zinc and two sodium ions. These structures are discussed with reference to Zn binding and activity. A catalytic mechanism is proposed which is coherent with metallo-β-lactamases being active with either one Zn ion (as in Aeromonas hydrophila) or two Zn ions (as in B. fragilis) bound to the protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S090744499700927X
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  • 8
    Electronic Resource
    Electronic Resource
    1.85 Å Resolution Structure of the ZincII β-Lactamase from Bacillus cereus (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 313-323 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Class B \beta-lactamases are wide spectrum enzymes which require bivalent metal ions for activity. The structure of the class B zinc-ion-dependent β-lactamase from Bacillus cereus (BCII) has been refined at 1.85 Å resolution using data collected on cryocooled crystals (100 K). The enzyme from B. cereus has a molecular mass of 24 946 Da and is folded into a \beta-sandwich structure with helices on the external faces. The active site is located in a groove running between the two \beta-sheets [Carfi et al. (1995). EMBO J. 14, 4914–4921]. The 100 K high-resolution BCII structure shows one fully and one partially occupied zinc site. The zinc ion in the fully occupied site (the catalytic zinc) is coordinated by three histidines and one water molecule. The second zinc ion is at 3.7 Å from the first one and is coordinated by one histidine, one cysteine, one aspartate and one unknown molecule (which is most likely to be a carbonate ion). In the B. cereus zinc \beta-lactamase the affinity for the second metal ion is low at the pH of crystallization (Kd = 25 mM, 293 K; [Baldwin et al. (1978). Biochem. J. 175, 441–447] and the dissociation constant of the second zinc ion thus apparently decreased at the cryogenic temperature. In addition, the structure of the apo enzyme was determined at 2.5 Å resolution. The removal of the zinc ion by chelating agents causes small changes in the active-site environment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444997010627
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  • 9
    Electronic Resource
    Electronic Resource
    Expression, purification, crystallization and preliminary X-ray analysis of the κ-carrageenase from Pseudoalteromonas carrageenovora (1999)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 55 (1999), S. 918-920 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A recombinant form of His-tagged κ-carrageenase from Pseudoalteromonas carrageenovora has been expressed, purified and crystallized. Crystals have been obtained by the vapour-diffusion method using polyethylene glycol (Mr = 4000) as a precipitant. These crystals belong to the space group P212121, with unit-cell parameters a  =  58.2, b  =  62.8, c  =  77.9 Å, and diffract to 2.2 Å resolution on a rotating-anode X-ray source.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444998018526
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  • 10
    Electronic Resource
    Electronic Resource
    β-Lactamase of Bacillus licheniformis 749/C at 2 Å resolution (1990)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 7 (1990), S. 156-171 
    Details
    ISSN: 0887-3585
    Keywords: β-lactamase ; penicillinase ; penicillin-binding protein ; penicillin antibiotics ; X-ray diffraction ; protein structure prediction ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Two crystal (A and B) of the 29,500 Da Class A β-lactamase (penicillinase) from Bacillus licheniformis 749/C have been examined crystallographically. The structure of B-form crystals has been solved to 2 Å resolution, the starting model for which was a 3.5 Å structure obtained from A-form crystals. The β-lactamase has an α + β structure with 11 helices and 5 β-strands seen also in a peinicilin target DD-peptidase of Streptomyces R61.1 Atomic parameters of the two molecules in the asymmetric unit were refined by simulated annealing at 2.0 Å resolution. The R factor is 0.208 for the 27,330 data greater than 3 (F), with water molecules excluded from the model. The catalytic Ser-70 is at the N-terminus of a helix and is within hydrogen bonding distance of conversed Lys-73. Also interacting with the Lys-73 are Asn-132 and the conserved Glu-166, which is on a potentially flexible helix-containing loop. The structure suggests the binding of β-lactam substrates is facilitated by interactions with Lys-234, Tyhr-235, and Ala-237 in a conserved β-strand peptide, which is antiparallel to the β-lactam's acylamido linkage; an exposed cavity near Asn-170 exits for acylamido Substituent. The reactive double bond of clavulanate-type inhibitors may interact with Arg-244 on the fourth β-strand. A very similar binding site architecture is seen in the DD-peptidase.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340070205
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