Rhizobium leguminosarum is a Gram-negative bacterium that forms nitrogen-fixing symbioses with compatible leguminous plants via intracellular invasion and establishes a persistent infection within host membranederived subcellular compartments. Notably, an unusual very-long-chain fatty acid (VLCFA) is found in the lipid A of R. leguminosarum as well as in the lipid A of the medically relevant pathogens Brucella abortus, Brucella melitensis, Bartonella henselae, and Legionella pneumophila, which are also able to persist within intracellular host-derived membranes. These bacterial symbionts and pathogens each contain a homologous gene region necessary for the synthesis and transfer of the VLCFA to the lipid A. Within this region lies a gene that encodes the specialized acyl carrier protein AcpXL, on which the VLCFA is built. This study describes the biochemical and infection phenotypes of an acpXL mutant which lacks the VLCFA. The mutation was created in R. leguminosarum bv. phaseoli strain 8002, which forms symbiosis with Phaseolus vulgaris, a determinate nodulating legume. Structural analysis using gas chromatography and mass spectrometry revealed that the mutant lipid A lacked the VLCFA. Compared to the parent strain, the mutant was more sensitive to the detergents deoxycholate and dodecyl sulfate and the antimicrobial peptide polymyxin B, suggesting a compromise to membrane stability. In addition, the mutant was more sensitive to higher salt concentrations. Passage through the plant restored salt tolerance. Electron microscopic examination showed that the mutant was developmentally delayed during symbiotic infection of the host plant Phaseolus vulgaris and produced abnormal symbiosome structures.Rhizobium leguminosarum is a Gram-negative alphaproteobacterium capable of forming nitrogen-fixing symbioses with plants found in the Leguminosae family. The symbiotic process involves the formation of root nodules and simultaneous invasion of the legume root by compatible symbiotic bacteria. The invading bacteria are eventually endocytosed by specialized root nodule tissue, where they develop into nitrogen-fixing bacteroids. Bacteroids persist within plant-derived membranes (peribacteroid membrane), which together form organelle-like structures (symbiosomes) for which the primary function is to provide the plant with nitrogen through the conversion of atmospheric nitrogen to ammonia via the bacteroid-derived nitrogenase enzyme. For a recent review of the rhizobial infection process, refer to the study by Oldroyd and Downie (26).Depending on the legume host plant, two nodule types, indeterminate and determinate, are known, and key fundamental differences exist between the two nodule types. Indeterminate systems are characterized as having an active meristem during the entire life cycle of the nodule. Conversely, meristematic cells from determinate root nodules stop dividing well before nodule senescence. Indeterminate nodules have an oblong shape and harbor terminally differentiated bacteroids (inhibited in cell divisio...

During a 2-year period, 34 patients of catatonic features in Chinese ethnic background Taiwanese were brought to the emergency unit of Chang Gung Memorial Hospital at Linkou. The ratios of the causes of catatonic features by schizophrenic disorders, mood disorders, neuroleptic-induced disorders, and general medical conditions were 26, 9, 24 and 41%, respectively. After the treatments of antipsychotics, benzodiazepam, or electroconvulsive therapy (ECT), 24 patients (70.6%) showed complete remission, seven patients (20.6%) showed partial remission, and three patients (8.8%) showed no response (two died). Additionally, a suggestive period is proposed in order to distinguish acute and insidious onset catatonic conditions to help clinicians in deciding on probability immediately. The patients were grouped into four diagnostic categories; namely, schizophrenic disorders, mood disorders, neuroleptic-induced disorders, and general medical conditions for comparison. One-way A N OVA and Duncan's multiple-range test were used for continuous variables, and the Chi-squared test was used for categorical variables. The mean duration of 'insidious onset catatonic condition' (including schizophrenic disorders and general medical conditions) before seeking medical help was longer than 3.33 weeks, while the mean duration of 'acute catatonic condition' (including mood disorders and neurolepticinduced disorders) was shorter than 1.83 weeks. These findings suggest that 2-3 weeks would be a cut-off point for acute or insidious onsets of catatonic conditions.

Human glutathione transferase (GST ) has been crystallized as a homodimer, with a subunit molecular mass of ϳ23 kDa; however, in solution the average molecular mass depends on protein concentration, approaching that of monomer at <0.03 mg/ml, concentrations typically used to measure catalytic activity of the enzyme. Electrostatic interaction at the subunit interface greatly influences the dimer-monomer equilibrium of the enzyme and is an important force for holding subunits together. Arg-70, Arg-74, Asp-90, Asp-94, and Thr-67 were selected as target sites for mutagenesis, because they are at the subunit interface. R70Q, R74Q, D90N, D94N, and T67A mutant enzymes were constructed, expressed in Escherichia coli, and purified. The construct of N-terminal His tag enzyme facilitates the purification of GST , resulting in a high yield of enzyme, but does not alter the kinetic parameters or secondary structure of the enzyme. Our results indicate that these mutant enzymes show no appreciable changes in K m for 1-chloro-2,4-dinitrobenzene and have similar CD spectra to that of wild-type enzyme. However, elimination of the charges of either Arg-70, Arg-74, Asp-90, or Asp-94 shifts the dimer-monomer equilibrium toward monomer. In addition, replacement of Asp-94 or Arg-70 causes a large increase in the K m GSH , whereas substitution for Asp-90 or Arg-74 primarily results in a marked decrease in V max . The GST retains substantial catalytic activity as a monomer probably because the glutathione and electrophilic substrate sites (such as for 1-chloro-2,4-dinitrobenzene) are predominantly located within each subunit.

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