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661.
Munro CA Bates S Buurman ET Hughes HB Maccallum DM Bertram G Atrih A Ferguson MA Bain JM Brand A Hamilton S Westwater C Thomson LM Brown AJ Odds FC Gow NA 《The Journal of biological chemistry》2005,280(2):1051-1060
The MNT1 gene of the human fungal pathogen Candida albicans is involved in O-glycosylation of cell wall and secreted proteins and is important for adherence of C. albicans to host surfaces and for virulence. Here we describe the molecular analysis of CaMNT2, a second member of the MNT1-like gene family in C. albicans. Mnt2p also functions in O-glycosylation. Mnt1p and Mnt2p encode partially redundant alpha-1,2-mannosyltransferases that catalyze the addition of the second and third mannose residues in an O-linked mannose pentamer. Deletion of both copies of MNT1 and MNT2 resulted in reduction in the level of in vitro mannosyltransferase activity and truncation of O-mannan. Both the mnt2Delta and mnt1Delta single mutants were significantly reduced in adherence to human buccal epithelial cells and Matrigel-coated surfaces, indicating a role for O-glycosylated cell wall proteins or O-mannan itself in adhesion to host surfaces. The double mnt1Deltamnt2Delta mutant formed aggregates of cells that appeared to be the result of abnormal cell separation. The double mutant was attenuated in virulence, underlining the importance of O-glycosylation in pathogenesis of C. albicans infections. 相似文献
662.
McGoldrick HM Roessner CA Raux E Lawrence AD McLean KJ Munro AW Santabarbara S Rigby SE Heathcote P Scott AI Warren MJ 《The Journal of biological chemistry》2005,280(2):1086-1094
One of the most intriguing steps during cobalamin (vitamin B12) biosynthesis is the ring contraction process that leads to the extrusion of one of the integral macrocyclic carbon atoms from the tetrapyrrole-derived framework. The aerobic cobalamin pathway requires the action of a monooxygenase called CobG (precorrin-3B synthase), which generates a hydroxylactone intermediate that is subsequently ring-contracted by CobJ. However, in the photosynthetic bacterium Rhodobacter capsulatus, which harbors an aerobic-like pathway, there is no cobG in the main cobalamin biosynthetic operon although it does contain an additional uncharacterized gene called orf663. To demonstrate the involvement of Orf663 in cobalamin synthesis, the first dedicated 10 genes of the B12 pathway (including orf663), encoding enzymes for the transformation of uroporphyrinogen III into hydrogenobyrinic acid (HBA), were sequentially cloned into a plasmid to generate an artificial operon, which, when transformed into Escherichia coli, endowed the host with the ability to make HBA. Deletion of orf663 from this operon prevented HBA synthesis, demonstrating that it was essential for corrin construction. HBA synthesis was restored to this recombinant strain either by returning orf663 or by substituting it with cobG. Recombinant overproduction of Orf663, now renamed CobZ, allowed the characterization of a novel cofactor-rich protein, housing two Fe-S centers, a flavin, and a heme group, which like B12 itself is a modified tetrapyrrole. A mechanism for Orf663 (CobZ) in cobalamin biosynthesis is proposed. 相似文献
663.
Munro S 《Nature cell biology》2002,4(10):E223-E224
664.
Nicola T. Munro David B. Lindenmayer Joern Fischer 《Ecological Management & Restoration》2007,8(3):199-207
Summary We reviewed the literature on fauna in revegetation in Australian agricultural areas. Of 27 studies, 22 examined birds, with few studies focusing on other faunal groups (four to six studies for each remaining group) and nine examined multiple groups. Existing evidence suggests that revegetation provides habitat for many species of bird and some arboreal marsupials. Species richness of birds was greater in revegetated areas that were large, wide, structurally complex, old and near remnant vegetation. Bats, small terrestrial mammals, reptiles and amphibians did not appear to benefit significantly from revegetation in the short term. Evidence to date suggests that revegetation is not a good replacement of remnant vegetation for many species. Key information gaps exist in the faunal response to (i) revegetation as it ages; (ii) different structural complexities of revegetation; (iii) revegetation that is composed of indigenous vs. non-indigenous plant species; and (iv) revegetation that is in riparian vs. non-riparian locations. In addition, little is known on the value of revegetation for declining or threatened fauna, or of the composition of fauna in revegetation. There is a need to better understand the balance between quantity of revegetation in the landscape, and the quality or complexity of revegetation at the patch scale. Based on current evidence, we recommend revegetation be conducted in patches that are large, wide and structurally complex to maximize the benefits to fauna. 相似文献
665.
Human PrP (residues 91-231) expressed in Escherichia coli can adopt several conformations in solution depending on pH, redox conditions and denaturant concentration. Oxidised PrP at neutral pH, with the disulphide bond intact, is a soluble monomer which contains 47% alpha-helix and corresponds to PrPC. Denaturation studies show that this structure has a relatively small, solvent-excluded core and unfolds to an unstructured state in a single, co-operative transition with a DeltaG for folding of -5.6 kcal mol-1. The unfolding behaviour is sensitive to pH and at 4.0 or below the molecule unfolds via a stable folding intermediate. This equilibrium intermediate has a reduced helical content and aggregates over several hours. When the disulphide bond is reduced the protein adopts different conformations depending upon pH. At neutral pH or above, the reduced protein has an alpha-helical fold, which is identical to that observed for the oxidised protein. At pH 4 or below, the conformation rearranges to a fold that contains a high proportion of beta-sheet structure. In the reduced state the alpha- and beta-forms are slowly inter-convertible whereas when oxidised the protein can only adopt an alpha-conformation in free solution. The data we present here shows that the human prion protein can exist in multiple conformations some of which are known to be capable of forming fibrils. The precise conformation that human PrP adopts and the pathways for unfolding are dependent upon solvent conditions. The conditions we examined are within the range that a protein may encounter in sub-cellular compartments and may have implications for the mechanism of conversion of PrPC to PrPSc in vivo. Since the conversion of PrPC to PrPSc is accompanied by a switch in secondary structure from alpha to beta, this system provides a useful model for studying major structural rearrangements in the prion protein. 相似文献
666.
Noble MA Munro AW Rivers SL Robledo L Daff SN Yellowlees LJ Shimizu T Sagami I Guillemette JG Chapman SK 《Biochemistry》1999,38(50):16413-16418
Midpoint reduction potentials for the flavin cofactors in the reductase domain of rat neuronal nitric oxide synthase (nNOS) in calmodulin (CaM)-free and -bound forms have been determined by direct anaerobic titration. In the CaM-free form, the FMN potentials are -49 +/- 5 mV (oxidized/semiquinone) -274 +/- 5 mV (semiquinone/reduced). The corresponding FAD potentials are -232 +/- 7, and -280 +/- 6 mV. The data indicate that each flavin can exist as a blue (neutral) semiquinone. The accumulation of blue semiquinone on the FMN is considerably higher than seen on the FAD due to the much larger separation (225 mV) of its two potentials (cf. 48 mV for FAD). For the CaM-bound form of the protein, the midpoint potentials are essentially identical: there is a small alteration in the FMN oxidized/semiquinone potential (-30 +/- 4 mV); the other three potentials are unaffected. The heme midpoint potentials for nNOS [-239 mV, L-Arg-free; -220 mV, L-Arg-bound; Presta, A., Weber-Main, A. M., Stankovich, M. T., and Stuehr, D. J. (1998) J. Am. Chem. Soc. 120, 9460-9465] are poised such that electron transfer from flavin domain is thermodynamically feasible. Clearly, CaM binding is necessary in eliciting conformational changes that enhance flavin to flavin and flavin to heme electron transfers rather than causing a change in the driving force. 相似文献
667.
668.
669.
D. W. Bruno A. L. S. Munro J. G. McHenery 《Zeitschrift fur angewandte Ichthyologie》1990,6(2):124-127
The treatment of sea lice, Lepeophtheirus salmonis infestations on farmed Atlantic salmon, Salmo salar requires regular bathing of the fish in diachlorvos (DDVP), 2,2-dichlorovinyl dimethyl phosphate, with subsequent release to the marine environment of spent pesticide. The toxicity of a possible alternative compound, carbaryl, l-naphthyl N-methylcarbamate) to kill sea lice and Atlantic salmon was examined. Preliminary studies with carbaryl indicate the potential advantage of a reduced treatment dose was outweighed by the greater persistence of both the parent compound and of its toxic degradation product. Hence this carbamate insecticide is unlikely to be considered by regulatory authorities as an alternative treatment for sea lice infestations. 相似文献
670.
Martina?Pigoni Johanna?Wanngren Peer-Hendrik?Kuhn Kathryn?M.?Munro Jenny?M.?Gunnersen Hiroshi?Takeshima Regina?Feederle Iryna?Voytyuk Bart?De Strooper Mikail?D.?Levasseur Brian?J.?Hrupka Stephan?A.?Müller Stefan?F.?Lichtenthaler