Contribution of the Sensor Histidine Kinases PhcS and VsrA to the Quorum Sensing of Strain OE1-1.

The soilborne Gram-negative phytopathogenic beta-proteobacterium strain OE1-1 produces methyl 3-hydroxymyristate (3-OH MAME) as the quorum sensing (QS) signal by the methyltransferase PhcB and senses the chemical, activating the LysR family transcriptional regulator PhcA, which regulates the QS-dependent genes responsible for QS-dependent phenotypes including virulence. The sensor histidine kinases PhcS and VsrA are reportedly involved in the regulation of QS-dependent genes. To elucidate the function of PhcS and VsrA in the active QS, we generated the deletion and -deletion mutants, which exhibited weak changes to their QS-dependent phenotypes including virulence.

The transcription regulator ChpA affects the global transcriptome including quorum sensing-dependent genes in Ralstonia pseudosolanacearum strain OE1-1.

The gram-negative plant-pathogenic β-proteobacterium Ralstonia pseudosolanacearum strain OE1-1 produces methyl 3-hydroxymyristate as a quorum sensing (QS) signal through methyltransferase PhcB and senses the chemical via the sensor histidine kinase PhcS. This leads to activation of the LysR family transcription regulator PhcA, which regulates the genes (QS-dependent genes) responsible for QS-dependent phenotypes, including virulence. The transcription regulator ChpA, which possesses a response regulator receiver domain and also a hybrid sensor histidine kinase/response regulator phosphore-acceptor domain but lacks a DNA-binding domain, is reportedly involved in QS-dependent biofilm formation and virulence of R.

β-1,4-Cellobiohydrolase is involved in full expression of phcA, contributing to the feedback loop in quorum sensing of Ralstonia pseudosolanacearum strain OE1-1.

After infecting roots of tomato plants, the gram-negative bacterium Ralstonia pseudosolanacearum strain OE1-1 activates quorum sensing (QS) to induce production of plant cell wall-degrading enzymes, such as β-1,4-endoglucanase (Egl) and β-1,4-cellobiohydrolase (CbhA), via the LysR family transcriptional regulator PhcA and then invades xylem vessels to exhibit virulence. The phcA-deletion mutant (ΔphcA) exhibits neither the ability to infect xylem vessels nor virulence. Compared with strain OE1-1, the egl-deletion mutant (Δegl) exhibits lower cellulose degradation activity, lower infectivity in xylem vessels, and reduced virulence.

Complete genome sequence of a novel ophiovirus associated with chlorotic disease of pepper (Capsicum annuum L.) in Japan.

In July 2018, pepper plants (Capsicum annuum L.) with chlorotic leaves and fruits were observed in Kochi prefecture, Japan. High-throughput sequencing (HTS) identified the possible presence of an ophiovirus-like virus possessing three RNA segments in a chlorotic leaf.

The behavior of Ralstonia pseudosolanacearum strain OE1-1 and morphological changes of cells in tomato roots.

The soil-borne Gram-negative β-proteobacterium Ralstonia solanacearum species complex (RSSC) infects tomato roots through the wounds where secondary roots emerge, infecting xylem vessels. Because it is difficult to observe the behavior of RSSC by a fluorescence-based microscopic approach at high magnification, we have little information on its behavior at the root apexes in tomato roots. To analyze the infection route of a strain of phylotype I of RSSC, R.

Quorum Sensing Inhibition Attenuates the Virulence of the Plant Pathogen Species Complex.

Strains of species complex (RSSC) cause "bacterial wilt" on a wide range of plant species and thus lead to marked economic losses in agriculture. Quorum sensing (QS), a bacterial cell-cell communication mechanism, controls the virulence of RSSC strains by regulating the production of extracellular polysaccharide (EPS) and secondary metabolites, biofilm formation, and cellular motility. strain OE1-1 employs ()-methyl 3-hydroxymyristate (3-OH MAME) as a QS signal, which is synthesized by the PhcB methyltransferase and sensed by the PhcS/PhcRQ two-component system.

The putative sensor histidine kinase PhcK is required for the full expression of phcA encoding the global transcriptional regulator to drive the quorum-sensing circuit of Ralstonia solanacearum strain OE1-1.

A gram-negative plant-pathogenic bacterium Ralstonia solanacearum strain OE1-1 produces and extracellularly secretes methyl 3-hydroxymyristate (3-OH MAME), and senses the chemical as a quorum-sensing (QS) signal, activating QS. During QS a functional global transcriptional regulator PhcA, through the 3-OH MAME-dependent two-component system, induces the production of virulence factors including a major extracellular polysaccharide EPS I and ralfuranone. To elucidate the mechanisms of phcA regulation underlying the QS system, among Tn5-mutants from the strain OE1-1, we identified a mutant of RSc1351 gene (phcK), encoding a putative sensor histidine kinase, that exhibited significantly decreased QS-dependent cell aggregation.