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Physical and Enzymological Interaction of Bacillus subtilis Proteins Required for De Novo Pyridoxal 5'-Phosphate Biosynthesis. Boris R. Belitsky, 2004.Bacillus subtilis synthesizes pyridoxal 5'-phosphate, the active form of vitamin B6, by a poorly characterized pathway involving the yaaD and yaaE genes . The pdxS [yaaD] mutant was confirmedto be a strict B6 auxotroph, but the pdxT [yaaE] mutant turnedout to be a conditional auxotroph depending on the availabilityof ammonium in the growth medium . The PdxS and PdxT proteinscopurified during affinity chromatography and apparently forma complex that has glutaminase activity . PdxS and PdxT appearto encode the synthase and glutaminase subunits, respectively,of a glutamine amidotransferase of as-yet-unknown specificityessential for B6 biosynthesis. In Vitro Killing of Community-Associated Methicillin-Resistant Staphylococcus aureus with Drug Combinations. Samuel A. Shelburne, 2004.This study employs time-kill techniques to examine the most common drug combinations used in the therapy of methicillin-resistant Staphylococcus aureus (MRSA) infections, vancomycin plus either gentamicin or rifampin . Community-associated MRSA were more likely to be synergistically inhibited by combinations of vancomycin and gentamicin versus vancomycin alone compared to inhibition associated with hospital-acquired strains . Comparison of Shiga-Toxigenic Escherichia coli Prevalences among Dairy, Feedlot, and Cow-Calf Herds in Washington State. Rowland N. Cobbold, 2004. Purification of the Formate-Tetrahydrofolate Ligase from Methylobacterium extorquens AM1 and Demonstration of Its Requirement for Methylotrophic Growth. Christopher J. Marx, 2003.The serine cycle methylotroph Methylobacterium extorquens AM1 contains two pterin-dependent pathways for C1 transfers, the tetrahydrofolate (H4F) pathway and the tetrahydromethanopterin (H4MPT) pathway, and both are required for growth on C1 compounds . With the exception of formate-tetrahydrofolate ligase (FtfL, alternatively termed formyl-H4F synthetase), all of the genes encoding the enzymes comprising these two pathways have been identified, and the corresponding gene products have been purified and characterized . We present here the purification and characterization of FtfL from M. extorquens AM1 and the confirmation that this enzyme is encoded by an ftfL homolog identified previously through transposon mutagenesis . Phenotypic analyses of the ftfL mutant strain demonstrated that FtfL activity is required for growth on C1 compounds . Unlike mutants defective for the H4MPT pathway, the ftfL mutant strain does not exhibit phenotypes indicative of defective formaldehyde oxidation . Furthermore, the ftfL mutant strain remained competent for wild-type conversion of [14C]methanol to [14C]CO2 . Collectively, these data confirm our previous presumptions that the H4F pathway is not the key formaldehyde oxidation pathway in M . extorquens AM1 . Rather, our data suggest an alternative model for the role of the H4F pathway in this organism in which it functions to convert formate to methylene H4F for assimilatory metabolism . Tri16 Is Required for Esterification of Position C-8 during Trichothecene Mycotoxin Production by Fusarium sporotrichioides. Andrew W. Peplow, 2003.We previously characterized Tri1, a gene required for hydroxylation of the C-8 position during trichothecene mycotoxin biosynthesis in Fusarium sporotrichioides NRRL 3299 . Sequence analysis of the region surrounding Tri1 revealed a gene, named Tri16, which could encode an acyltransferase . Unlike the wild-type parent strain NRRL 3299, which accumulates primarily T-2 toxin along with low levels of diacetoxyscirpenol (DAS) and neosolaniol (NEO) and trace amounts of 8-propionyl-neosolaniol (P-NEO) and 8-isobutyryl-neosolaniol (B-NEO), mutants containing a disruption of Tri16 were blocked in the production of the three C-8 esterified compounds T-2 toxin, P-NEO, and B-NEO and accumulated the C-8-hydroxylated compound NEO along with secondary levels of DAS . These data indicate that Tri16 encodes an acyltransferase that catalyzes the formation of ester side groups at C-8 during trichothecene biosynthesis . We also report the presence of a Tri16 ortholog in Gibberella pulicaris R-6380 that is likely linked to a presumably inactive ortholog for Tri1 .
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