The analysis of genetics and physiological functions of Agrobacterium tumefaciens RirA (rhizobial iron regulator) has shown that it is a transcription regulator and a repressor of iron uptake systems. The rirA mutant strain (NTLrirA) overproduced siderophores and exhibited a highly constitutive expression of genes involved in iron uptake (fhuA, irp6A, and fbpA) compared to that of the wild-type strain (NTL4). The deregulation in the iron control of iron uptake in NTLrirA led to iron overload in the cell, which was supported by the observation that the NTLrirA mutant was more sensitive than wild-type NTL4 to an iron-activated antibiotic, streptonigrin. The NTLrirA mutant was more sensitive than the parental strain to oxidants, including hydrogen peroxide, organic hydroperoxide, and a superoxide generator, menadione. However, the addition of an iron chelator, 2,2-dipyridyl, reversed the mutant hypersensitivity to H 2 O 2 and organic hydroperoxide, indicating the role of iron in peroxide toxicity. Meanwhile, the reduced level of superoxide dismutase (SodBIII) was partly responsible for the menadione-sensitive phenotype of the NTLrirA mutant. The NTLrirA mutant showed a defect in tumorigenesis on tobacco leaves, which likely resulted from the increased sensitivity of NTLrirA to oxidants and the decreased ability of NTLrirA to induce virulence genes (virB and virE). These data demonstrated that RirA is important for A. tumefaciens during plant-pathogen interactions.

BackgroundData on encephalitis in Thailand have not been completely described. Etiologies remain largely unknown. We prospectively analyzed 103 Thai patients from 27 provinces for the causes of encephalitis using clinical, microbiological and neuroimaging indices; caseswithout a diagnosis were evaluated for autoimmune causes of encephalitis.MethodsPatients with encephalitis and/or myelitis were prospectively studied between October 2010 and August 2012. Cases associated with bacterial, rickettsial and mycobacterial diseases were excluded. Herpes viruses 1-6 and enteroviruses infection was diagnosed using PCR evaluation of CSF; dengue and JE viruses infection, by serology. The serum of test-negative patients was evaluated for the presence of autoantibodies.Results103 patients were recruited. Fifty-three patients (52%) had no etiologies identified. Twenty-five patients (24%) were associated with infections. Immune encephalitis was found in 25 (24%); neuropsychiatric lupus erythematosus (4), demyelinating diseases (3), Behcet’s disease (1) and the remaining had antibodies to NMDAR (5), ANNA-2 (6), Yo (2), AMPA (1), GABA (1), VGKC (1) and NMDA coexisting with ANNA-2 (1). Presenting symptoms in the autoimmune group included behavioral changes in 6/25 (versus 12/25 in infectious and 13/53 in unknown group) and as psychosis in 6/25 (versus 0/25 infectious and 2/53 unknown). Seizures were found in 6/25 autoimmune, 4/25 infectious and 19/53 unknown group. Two patients with anti-ANNA-2 and one anti-Yo had temporal lobe involvement by magnetic resonance imaging. Two immune encephalitis patients with antibodies to NMDAR and ANNA-2 had ovarian tumors.ConclusionsAutoantibody-associated encephalitis should be considered in the differential diagnosis and management algorithm regardless of clinical and neuroimaging features.

In Xanthomonas campestris pv. campestris, SoxR likely functions as a sensor of redox-cycling drugs and as a transcriptional regulator. Oxidized SoxR binds directly to its target site and activates the expression of xcc0300, a gene that has protective roles against the toxicity of redox-cycling compounds. In addition, SoxR acts as a noninducible repressor of its own expression. X. campestris pv. campestris requires SoxR both for protection against redox-cycling drugs and for full virulence on a host plant. The X. campestris model of the gene regulation and physiological roles of SoxR represents a novel variant of existing bacterial SoxR models.